Mercedes Volait

Experimenting with subsidised terraced housing: Mahmoud Riad's garden suburbs 1950-54

The development of subsidised housing in Egypt has long been considered a legacy of Nasserism. 1 By the same token, Hassan Fathy's New Gurna (Upper Egypt) was commonly dated after 1952. Both conceptions are misleading. 2 The provision of affordable housing to low-income urban dwellers is a concern that can be traced back to at least the interwar period. 3 New Gurna model village started in 1947, and is rooted in the programmes of rural reform that were launched in Egypt in the 1930s. 4 The idea of subsidised housing emerged in the late 1940s; architect Mahmoud Riad 5 (1905-1979) was a key player in its dynamics and provided a significant contribution, although implementation took place after 1952.

An enduring concern in pre-Nasserist Egypt

A prime milestone in the public involvement with housing for low-income groups can be situated in the immediate aftermath of World War I. Construction work had virtually stopped during wartime. The supply of coal and other building materials had ceased, and no alternative power allowed continuing the manufacturing of bricks, lime or cement locally. The acute housing shortage that ensued (a report estimated it to be of 8,000 houses in Cairo alone), 6 coupled with dramatic inflation, affected not only lower income groups, but indeed the middle class.

Governmental intervention was envisioned in order to stimulate the construction of affordable dwellings. Land development companies and major employers were encouraged to lead the effort. The Heliopolis Oasis Company implemented a significant subsidized housing scheme in 1920-23 against the permission of further urban expansion. 615 dwellings were built and rented under market prices to low-rank government employees and local workers of the company. In the process, new typologies such as the four-apartment house with individual gardens were introduced. 7

The Misr textile group, a holding created in 1927 to encourage Egyptian industry, started building large company towns during World War Two, at Mahalla al-Kubra (in two phases, 1941-47, and 1946-51, the latter on designs by Egyptian architect ʿAli Labib Gabr and town-planner ʿAli al-Maligi Massaʿud). Considered as "outstanding examples of housing for industrial workers" and the "last word of modernity," the self-contained schemes included, besides dwelling units, all modern amenities: central restaurants and hospitals, markets and coffee shops, an open-air cinema, welfare centres, sporting fields, bathhouses, and automated laundry facilities. 8 By 1950, twenty-two other enterprises had erected dwellings for their white-collar employees and 1 After Janet Abu Lughod, Cairo. The 1001 Years of the City Victorious. Princeton: Princeton University Press, 1971, p. 231. 2 See Mercedes Volait, "Réforme sociale et habitat populaire : Acteurs et formes (1848-1964)", in Entre réforme sociale et mouvement national : Identité et modernisation en Égypte (1882-1962), edited by Alain Roussillon. Cairo : CEDEJ, 1995, p. 379-410 (Arabic version in Misr wa al-ʿalâm al-ʿarabî, no. 4 (1995) : 9-54). 3 Yahia Shawkat, Egypt's Housing Crisis: The Shaping of Urban Space. Cairo: AUC Press, 2020, chapters 4 and 5. 4 Mercedes Volait, "The Early Steps of a 'Romantic' in Liberal Egypt," in Hassan Fathy, an Architectural Life, edited by Leila El-Wakil. Cairo: AUC, 2018, p. 64-77. 5 I chose to keep the name of Riad in the transliteration himself used in his writings in English. workers. 9 In addition, there had been also some municipal efforts to house government workers. In 1947, the Department of Municipal Affairs (then within the Ministry of Interior) had launched a 6,000-unit scheme for workers attached to governmental workshops in Cairo, on designs made by ʿAli al-Maligi Massa'ud in his capacity of head of the Town planning bureau of the Department. The scheme was meant to decongest the densely-populated neighbourhood where these workshops were located (Bulaq) and offer salubrious accommodation to their moderate-income workers just across the Nile at Imbaba. In 1950, 1,100 terraced apartments were achieved using the traditional British model of back-to-back 2-floor row housing, as well as some semi-detached units, with facades in stone, brick and plaster finishes in order to overcome monotony. 10 [Fig. 2.2] A larger scheme was envisioned in parallel. In 1949, the Council of Ministers had approved the allocation of further state land for economic housing to be built for government employees in the vicinity of Cairo, at Helwan (in the south) and Hilmiyyat al-Zaytun (North East), on zones that have been initially reserved, in 1938, for industrial development. 11 Yet, housing civil servants and the industrial workforce only met a fraction of what was needed. As social reformers raised their voices louder in the 1930s, slum clearance and the provision of healthy dwellings in urban and rural areas came to the forefront. The largest share of the Egyptian population (75% in 1927) lived in the countryside in appalling conditions. A number of initiatives were developed to provide sanitization for the Egyptian village. Regulations were passed in 1933 and a few model villages were built by progressive landowners; recommended designs were disseminated through publications and industrial fairs. A Ministry of Social Affairs was established in 1939, with a department devoted to the Peasant (known as the Fellah Department) that instigated more model village construction. It was in this context that Hassan Fathy started experimenting with mud brick architecture for a model village at Bahtim (1940), following early uses of adobe construction in the US, and for a self-sufficient pilot community at New Gurna (1947-53).

In the same years, social scientist Ahmed Hussein (1902-1984) and architect and planner Mahmoud Riad embarked upon designing a scheme to provide housing for people with limited income.

Joining efforts: the collaboration of Ahmed Hussein and Mahmoud Riad

A committed social reformer, Ahmed Hussein had had an education in agricultural economics at Berlin University, gaining his Doctoral degree in 1927. While teaching at Cairo University upon his return from Germany, he had helped establish in 1937 the Egyptian Association for Social Studies, whose primary goals was the implementation of exemplary projects to find the best path to social reform. The group pushed for the creation of a governmental body which could "address all social and labour issues in both urban and rural Egypt": the Ministry of Social Affairs was created in 1939 to that effect. Ahmed Hussein was appointed head of its Fellah Department, where he worked in particular at the creation of Rural Social Centres across the country. 12 While primarily committed to rural welfare, Hussein did also engage with broader issues, among them social insurance for all and affordable housing for the unprivileged. the Ministry of Social affairs, he envisioned solutions for the latter problem. Associated to the task was architect Mahmoud Riad, who had been studying prototypes of low cost housing since his return from specialisation abroad.

After graduating from the Polytechnic School in Cairo in 1928, Riad benefited from the Egyptian Educational Mission Abroad program, which funded government employees to pursue higher education in Europe. Riad joined the small cohort of Egyptian architects who have had the opportunity through this scheme to specialise in "Civic design" at the Liverpool University School of Architecture, graduating in 1932 with a project for Alexandria. 13 The Liverpool School had been a pioneer in offering courses and degrees since 1909 on the discipline known nowadays as town planning. Throughout his time at Liverpool, Riad was exposed to the teaching of Sir Patrick Abercrombie (1879-1957), a follower of the survey-based planning philosophy of Patrick Geddes, and the future central figure behind the rebuilding of post-war London. A promoter of the moral mission of planning, Abercrombie equally saw its function as one able to work out "effects of civic beauty" through design. [START_REF] Photograph | [END_REF] Riad was subsequently appointed to the Building Department of the Ministry of Endowments (Awqaf) in Cairo, rising to the position of chief engineer in 1946. In this capacity, he was entrusted to design the plan of Madinat al-Awqaf, a large suburban extension on the West bank of the Nile at Cairo, today known as Muhandissin. The new development was advertised in the engineering press in 1948 as one combining "the beauty of Vienna and the elegance of Paris." 15 Interestingly enough, they were two of the three capitals that Abercrombie had studied, with Brussels, for the thesis he had presented in 1915. 16 Abercrombie's studies and teaching were seemingly not lost on Riad. His scheme for Madinat al-Awqaf was a grand one with large ways, a park-system, and ample perspectives, in the spirit of the British Civic Art and American City Beautiful movements, both rooted in French Beaux-Arts Classicism. [Fig. 2

.3]

In parallel, Riad developed an interest in low cost housing. In 1934, he had gained a prize for a model housing and scheme he had submitted for the layout of a Worker's city at Abu Zaʿbal (Cairo's northern outskirts). 17 A decade later, he was commissioned to design workers dwellings for the Misr Fine Spinning & Weaving Co at Kafr al-Dawwar, near Alexandria, 1943-46. The Company, also part of the Misr Group, had been created in 1938 to spin and weave fine gray cloths from Egyptian cotton, to be dyed and finished at a near-by company, Beida Dyers, created the same year. Both companies were founded with British capital (a minimal participation of 20 % in the former, and conversely 80 % in the latter, both coming from the British firm Bradford Dyers). 18 Both engaged in housing schemes for workers. Beida Dyers commissioned its own to the joint architectural firm of British John Prosper Serjeant (1898-1977) and Swiss Max Werner Zollikofer (1903-1966), while Misr Fine Spinning and Weaving entrusted to Mahmoud Riad the design of its company town. 366 units were built in a first phase, along a main model of attached 2-storey family units of 60 square meters with back yards, arranged in rows and separated by 20-m wide streets. 19 (Fig 2 .6 and 2.5) The dwelling type was a minimal unit made up of a living-room, kitchen and toilets on the first floor, and 2 bedrooms in the upper-floor, with a small balcony attached to the master one. It nevertheless represented a huge improvement considering the actual dwelling conditions of industrial workers. An extension, in form of a "garden-city," 13 Mahmoud Riad, "Alexandria: Its Town Planning Development," The Town Planning Review XV, no.4 (December 1933): 233-48. [START_REF] Photograph | [END_REF] (1930-1956). Cairo: AUC, 1989, p. 39-42. 19 Mahmoud Riad, "Masakin al-ʿummal," [Workers's housing], Magalla al-muhandisin (November 1947): 14-20.

Hadaʾiq Kafr al-Dawwar, possibly for self-built housing, was also designed by Riad. [Fig. 2.4] By 1949, the Misr Fine Spinning & Weaving Company was reported to have been building near its mills over 1,000 dwellings for the workmen, 240 other for skilled operatives, whilst foremen were housed in 6 apartment buildings. There are discrepancies in the available figures, as another source stated that about 2,500 dwelling units had been erected in total, of which 15 villas for engineers, 301 flats for the administrative personnel, and 2,168 flats and houses for the workers. 20 Whatever the case, it was a very large housing scheme, the largest in Egypt at the time. On the premises was a "most up-to-date restaurant, the first of its kind in Egypt and capable of seating 1,000 persons at a time", as well as a social hall, recreation room, sports ground and a library. 21 It was post-war time: optimism and faith in progress and welfare dominated the era.

Providing limited-income groups with decent housing

It is most probably his work at Kafr al-Dawwar which qualified to work out with Hussein a scheme for providing housing to low-income groups. The 77-page document was published in 1949 under the title Mashruʿ li-tawfir al-sakan lil-tabaqat al-mahdudat al-dakhl fi misr, but sadly only a digest released in 1950 survives as "Summary of a report on the housing problem in Egypt with proposals for a ten-year plan." 22 Its main conclusion was that housing provision could not be sustainable in Egypt within strict market-economy. Based on available figures, the report estimated at 140,000 the number of dwelling units to be built in the following decade in order to cope with the country's situation, of which 40,000 in urban centres and 100,000 in the countryside. The calculation was based on population increase (since 1927, the country had gained 5 million inhabitants), building rates of new houses, average family size (5 persons) and rural-urban migration fluxes.

At market conditions, this would mean in the best-case scenario (an average total cost of EGP 200 per unit and a monthly rent of EGP 1), an annual capital return of 6%, which was not sufficient to cover interest, maintenance, management and taxes -8% was the minimum requested. But even those low figures were unattainable for most. The average monthly income of workers was EGP 2.68 and only 1/6 of it could go for the rent. In addition, the average building cost had risen to EGP 600 per unit. The conclusion was all too obvious: the government needed to finance and subsidise housing.

A comprehensive program combining construction, land reservation, financing and changes in building materials was formulated by Hussein and Riad in order to address the situation. It suggested leasing at nominal rent government-owned land for economic housing, to increase public housing construction for civil servants, to provide financial assistance to interested parties and to experiment with new materials.

In 1950, Hussein became Minister of Social Affairs and was in position to take action. In March, he created a Department for Popular Housing (maslaha al-masakin al-shaʿbiyya) and named Mahmoud Riad as its head, a position he retained until 1953. A first initiative was to draft a law regulating governmental support to the construction of affordable housing for renting purposes. It was adopted by Parliament in October 1951 as Law no. 206-1951 on Popular Housing. Its stipulations granted a number of facilities to companies committing to build affordable housing; among them were access to public building land at reduced cost, exemptions on land taxes and rebates on customs duties due on imported building materials and machinery. 23 20 Ministry of Social Affairs, Social Welfare in Egypt, op. cit., p. 66. 21 "Société Misr pour la filature et le tissage fin en coton égyptien," in Clément Levy, The Stock Exchange Year-Book of Egypt. Cairo, 1949, p. 499-501. 22 Ministry of Social Affairs, Social Welfare in Egypt, op. cit., p. 113-16; see also Johnson, op. cit., p. 128-30. While listed in the catalogue of the National Library in Cairo, the original report has not been seen in place since the early 1990s and no other copy has been identified so far. 23 "La construction de logements avec l'aide de l'État en Égypte," in Bureau International du Travail, Informations sociales VII, no. 1 (May 1 st , 1952): 387-90.

The law was prepared with technical assistance received from abroad. In 1950, Professor Hans Spiegel (1893-1987) from Germany had been asked to produce propositions for social housing in Egypt. [START_REF] Dr | Hans Spiegel 80 Jahre[END_REF] The purpose was to seek ways of reducing construction costs to EGP250 per dwelling unit. A specialist of standardised and prefabricated housing, Spiegel had experimented initially with steel frames for house construction. [START_REF]A[END_REF] He is credited as one of the pioneering German architects who, like Ernst May and Martin Wagner, researched ways to rationalise architecture, by developing flexible construction kits and conceiving efficient assembly lines for serial production. [START_REF] Junghanns | Zur Geschichte der Vorfertigung in Deutschland[END_REF] After studying the Egyptian situation in matter of housing needs and building conditions, Spiegel rejected mud brick construction as a system with a short life cycle (2 or 3 years maximum before it started disintegrating and called for repair) and one favouring the spread of vermin. [START_REF] Spiegel | Arbeit für den sozialen Wohnungsbau in Agypten[END_REF] He also came to the conclusion that prefabricated housing was not an option in Egypt as it required a highly qualified workforce that was already fully absorbed by construction work in the main cities. He proposed instead to experiment with semi-assembled units, which components could be prepared on site by less qualified workers through using foamed concrete, such as "Betocel", a porous cement-type material invented in 1944 by French engineer René Fays, or the "Ribal" system of hollow concrete blocks, developed by Dr. Abdellatif with rice straw ashes. Orientation was given priority in the design of the dwellings in order to make the most of natural ventilation and protection from the heat. Two prototypes were built at Kafr al-Dawwar and were ready in 30 days. Spiegel was also consulted on the possibility of using for doors and windows artificial wood made out of sugar cane waste, a material which could be easily manufactured in Egypt where sugar cane was abundant. He calculated that with local materials, 100,000 units a year could be built at an average cost of EGP 250 per unit. Three factories, located at Cairo, Alexandria and Suez, would be sufficient to produce the required quantities. 28 Relying on local supplies appeared as the most appropriate option to many. Writing in October 1951, the British ambassador observed that "the Government [has] of late been showing some interest in the possibility of purchasing and erecting a large number of prefabricated houses to relieve the acute shortage of accommodation for people in the middle and lower income groups, but no decision has yet been reached on this." [START_REF]Commercial Relations and Exports Department, Economic and Commercial Conditions in Egypt[END_REF] The comment may have alluded to the introduction in Egypt of the patented system of prefabricated elements in vibrated reinforced concrete that had been invented by French engineer Eugène Mopin in 1928. [START_REF] Mopin | Procédés de construction par éléments standardisés en béton vibré[END_REF] A group of Egyptian industrial managers and building contractors had just created the Habeco Company, in full Société égyptienne d'habitations économiques [Egyptian Company for Economic Housing] in order to market in Egypt the Mopin process, for which they had obtained the concession for the whole Middle East. [START_REF]Fédération égyptienne des Industries[END_REF] Habeco likely used Mopin-patented prefabrication for works at Heliopolis, 32 but it is not clear if other applications took place. Whatever the case, the British diplomat doubted, as Spiegel, that "the ordinary European-type of prefabricated structure would be suitable for Egypt." [START_REF]Commercial Relations and Exports Department, Economic and Commercial Conditions in Egypt[END_REF] A similar conclusion on prefabrication was reached by the American consultant summoned in 1952 by the Technical Cooperation Administration of the State Department in the US, to study the same issue on request from the Egyptian government. The verdict on building material diverged however, at least for village construction. After visiting 25 recent housing developments, mostly located in rural areas but also in company towns and suburban estates, the report concluded that "costs of village construction can be kept at a minimum by making fullest use of the universal raw material, Nile clay properly handled, for walls, roofs and floors, using burned bricks in foundations and sun-dried brick for the rest of the house." 34 In the wake of Law 206-1951, the Department for Popular Housing started studying housing types inspired by the ones implemented at Kafr al-Dawwar by Mahmoud Riad, in order to launch the construction of 3,500 subsidized dwellings in Cairo. It seemingly put into practice the building process devised by Hans Spiegel for semi-assembled units. 35

Implementing the scheme

The scheme was mainly implemented in 1953 and 1954, with a few alterations following the change of regime that took power in 1952 at the initiative of the Free Officers. In particular, it was decided to increase to 4,000 the units to be built and to use for the purpose three zones that had been previously allocated for governmentemployees housing in 1949 (on land initially devoted to industry). The categories of beneficiaries were enlarged to anyone with monthly wages between EGP10 and 25, whether white-or blue-collars, in the public sector or not. It was also decided to offer the units for ownership rather than rent, thus transferring maintenance costs to individual owners. A committee was formed with engineers from various technical services across the Egyptian administration in order to fix the housing types to be implemented. Several types were considered and discussed. Low-density housing (1 to 2 storeys) was ultimately preferred to multi-storey buildings, on the basis of 30 units per feddan. 36 Three variants of the 2-storey attached townhouses were designed. Model A and C were conceived by Mahmoud Riad and ʿAli Khayrat; model B was designed by Hamid Mukhtar, an engineer who had studied sanitary engineering in London during the late 1920s. 37 The unit surface was increased to 70 sq meters and new hygienic norms were introduced. The eating-room was separated from the kitchen; bathroom and toilets were also disjointed and located at mid-floor in a rear appendix to each unit, and a "veranda" opening onto the back yard was added [Fig. 2.7 & 2.8].

The scheme was widely announced by the Department of Popular Housing (Ministry of Social Affairs); 18,000 application forms were distributed within a month, out of which 4,500 were immediately returned with the required down payment of EGP25, to the surprise of the Ministry. 38 In order to cope with the demand, a new organism was created under Law 601 of December 12, 1953: Shirka al-taʿmir wa al-masakin al-shaʿbiyya, with a 20% participation of the State in its capital and a guarantee of 4% return on investment for shareholders. A subsidy was set for each unit built in order to reduce expenses for beneficiaries. 39 Tenders were opened in March 1954 for the construction of 2,033 units at Imbaba and 650 at Hilmiyyat al-Zaytun. The former took place on the land reserved for the 6,000-unit housing scheme initiated at Imbaba in 1947, of which only one-sixth had been built. In the spirit of the 1952 Revolution, it was named Madinat al-Tahrir. [Fig. 2.9] A third location was chosen at Helwan for 600 further units. In a second phase, 2,000 new units were built at 34 Helmiyyat al-Zaytun. All were laid-out on the principle of row housing, with back-to-back yards, alternating with rows arranged around closes and squares. A key concept of garden-city design, a close refers to enclosed public space provided by a circular dead-end street, a U-shaped secondary street, or any other arrangement that leaves central space for a community garden or structure, thereby offering a sense of enclosure to fronting houses. 40 Provision was made for generous public space as well as schools, mosques, hospitals, and arcadedmarket places, in the spirit of the publicly-built garden-cities, organised around civic centres, of the interwar period in Britain and elsewhere.

When surveyed in 1991, 41 the three developments were being altered by the typical transformation process that consists in adding floors to any privately-owned construction in Egypt. [Fig. 2.11 & 2.14] Yet, from a few intact units [Fig. 2.12 & 2.13], one could get a glimpse of the homogenous urban scape that once was. Each site also still retained some of the urban qualities provided by the initial lay-out, and in particular the semiprivate space offered to children outside the houses and that opened on the communal green space. [Fig. 2.1]

A rare example of terraced housing in Egypt

In Egypt, Siedlungs for workers erected in the wake of the country's industrialisation provided an early step towards designing appropriate housing for the non-privileged, as exemplified by Mahmoud Riad's achievements at Kafr al-Dawwar and his subsequent governmental activity. The implementation phase of the scheme of 4,000 units of "popular housing" illustrates the combination of change and endurance of plans that characterises any urban development, even in times of strong political transformation. Initiated in 1950, the scheme was ultimately built from 1954 onward with some modifications, while keeping up with the initial spirit of the suburban terraced housing envisioned by British-trained Mahmoud Riad and the rationalised building process recommended by Hans Spiegel, the German expert who provided technical assistance. In this sense, Madinat al-Tahrir, Helmiyyat al-Zaytun and Helwan al-Gadida were mergers of know-hows: they are an amalgamation of European economic housing and building rationalisation, adapted to Egyptian social, climatic and labour conditions. They best exemplify the model of "global ambition and local knowledge" defining modernism in the Middle East in the very words of Gwendolyn Wright. 42 Launched in the immediate aftermath of the 1952 Revolution, the three subsidised housing estates are a living testimony of the dreams of social improvement raised by the post-war period and the new regime. The tragic defeat of 1967 made such hopes come to a halt. With most resources driven to the war effort, cheaper housing developments were devised. Subsidised family units were replaced by ill-constructed block-of-flats that deteriorated at fast pace; terraced housing was discontinued. Ulterior social housing policy makes the lowdense suburban schemes devised by Riad and Hussein even more unique.

Illustrations

2.1

Children playing in the semi-private lanes serving the dwellings opening onto the communal gardens, at Helwan al-Gadida, 1997.

8 "

 8 6 C. W. Haswell, "Town-Planning and Housing in Cairo," Garden Cities and Town Planning, a journal of housing, town planning and civic improvements 11 (1921): 256-58. 7 Annual Report of the Ministry of Public Works (Cairo), 1922/23, p. 19-21. See also M. Sabry Mahboub Bey. "Cairo. Some notes on its history, characteristics and town plan," Journal of the Town Planning Institute XXI (1934-35): 288-302. Madina al-ʿummal bi al-Mahalla al-Kubra," Magalla al-Muhandisin IV, no. 11 (November 1948): 36-40.

40

  The close was conceptualised by Raymond Unwin, Town Planning en Practice, an introduction to the Art of Designing Cities and Suburbs. London: T.F. Unwin, 1909, chapter 6 "Of Centers and enclosed places" passim. 41 Mercedes Volait, "De l'habitation salubre au logement de masse, L'expérimentation égyptienne en matière d'habitat économique et social," Rapport réalisé en juin 1991 pour le Bureau de la recherche architecturale, ministère de l'Équipement et du Logement, 136 pages. 42 Gwendolyn Wright, "Global Ambition and Local Knowledge," in Modernism and the Middle East. Architecture and Politics in the Twentieth Century, edited by Sandy Isenstadt and Kishwar Rizvi. Seattle: University of Washington Press, 2008, p. 221-54.

  During his tenure as Undersecretary of State in

	9 Ministry of Social Affairs, Social Welfare in Egypt. Cairo, 1950, p. 66.
	10 Hussein Mohammed Maged, "The Development and Economics of Low Cost Housing for Middle Class People in
	Egypt", MA thesis, Bartlett College, 1953, pl. 87-90; 'Ali al-Maligi Massaʿud, "Al-maskin al-sihhi min al-nahya al-
	takhtitiyya wa al-iqtisadiyya," [The salubrious dwelling from the planning and economic point of view], Al-'imara, no.
	5/6 (1947): 17-35.
	11 Tawfiq 'Abd al-Gawwad, "Muchkila al-masakin fi misr wa 'alagiha," [The problem of housing in Egypt and its
	solution], Al-'imara, no. 6/7/8 (1949): 71-84.
	12 On the creation of the Ministry, and Hussein's life-time achievements, see Amy J. Johnson, Reconstructing Rural
	Egypt, Ahmed Hussein and the History of Egyptian Development. Cairo: AUC Press, 2004, in particular chapter 3.

  Michiel Dehaene, "Urban Lessons for the Modern Planner: Patrick Abercrombie and the Study of Urban Development," The Town Planning Review 75, no. 1 (2004): 1-30. 15 Magalla al-Muhandissin, March 1948, unpaginated. 16 Under the title "The Development of the Plan and Architectural Character of three European Capitals -Paris, Vienna and Brussels;" see Michiel Dehaene. "Urban Lessons for the Modern Planner," op. cit.

17

Al-Musawwar, no. 482, January 5, 1934.

18

Robert Tignor, Egyptian Textiles and British Capital

  Arthur D. Little, "Preliminary Report on Egyptian Village Housing, Building Materials and Methods of Construction." Old Ills and New Remedies in Egypt. Cairo: Dar al-Maaref, 1958, p. 67-73; Samir Fikri, "Al-iskan al-shaʿbi fi misr," [Popular housing in Egypt], Al-'Imara, no. 1 (1957): 17-24.

	Cambridge, Massachusetts, April 1952, 95 pages.
	35 Fédération égyptienne des Industries, "Le bâtiment et la crise du logement," op. cit., p. 104-07.
	36 Ahmad Rifaʿt, "Machruʿat al-masakin al-shaʿbiyya," [Projects for popular housing], Al-'imara, no. 7/8 (1953/54):77-
	82.

37

Magalla al-muhandissin (March 1955):10-4.

38

Ahmad Rifaʿt, "Machruʿat al-masakin al-shaʿbiyya," [Projects for popular housing], op. cit.

39

Eva Garzouzi,


Elodie Conrath

Patrice Berthod
email: patrice.berthod@univ-lorraine.fr

Kinetic of oxidation at 1000, 1100 and 1200°C of 32.5wt.%Cr-containing Co-based alloys reinforced by hafnium carbides

Many cobalt-based superalloys and some nickel-based ones are reinforced by interdendritic carbides for allowing to use them in hot conditions [1]. Such carbides must be stable enough at high temperature in term of geometry/shape as well in term of volume fraction. The TaC carbides which reinforce some cobalt-based alloys do not rapidly evolve while TaC carbides are much less stable in chromium-rich nickel-based alloys (and even less stable than the chromium carbides in this second family of alloys [2]). HfC are among the carbides which are more stable at high temperature than the tantalum carbides, much more in the case of the nickel-based alloys [3] and already a little more in the case of the cobalt-based ones [4,5]. Hafnium carbides may potentially lead to nickel-based and cobalt-based alloys very resistant against creep deformation at high temperature but it was recently found that the HfC carbides network may be rather neutral for the behaviour of the nickel-based alloys in oxidation at high temperature [6], but detrimental for the alloys which are based on cobalt [7]. The good stability of the HfC carbides in the same families of alloys can be also exploited at lower temperatures such as 1100 and 1000°C. It appeared that it can be interesting to characterize the behaviour in oxidation at these temperatures of the same alloys already studied at 1200°C [6,7], in order to see if the behaviour of the cobalt-based alloys notably is improved 100°C or 200°C lower. Thus several new alloys with the same carbon (0.25 and 0.50 wt.%) and hafnium (3.7 to 7.4 wt.%) contents as the alloys previously studied at 1200°C were elaborated by foundry and tested in oxidation at 1100°C and 1000°C. The final mass gains, natures of oxides present externally and the values of parabolic constant and chromia volatilization constant (both extracted from the mass gain versus time file according to the {m x dm/dt = Kp -Kv x m} method [8]), clearly show that the behaviour of these alloys are really better, especially in the case of the cobalt alloys.

When the chromium content of these alloys is 7.5 wt.% higher, the microstructures are not significantly changed. They even tend to be more rich in HfC carbides, which is potentially better for their high temperature mechanical properties. In the field of the oxidation behavior at high temperature this increase in chromium content greatly improves the resistance of the alloys. The mass gain rates are much lower and the kinetics are more often parabolic than for the later alloys which tend to linearly oxidize.

Rather slow and parabolic kinetics seems showing that these HfC-reinforced cobalt-based alloys behave as chromia-former ones. X-ray diffraction runs and metallographic characterization are on going to verify this hypothesis. It is possible that additional increase in chromium content is still compulsory to ensure reproducible chromia-forming behavior in order to benefit on long times of the superior creep-resistance of such alloys at high temperature. Rather than Cr-increase of the bulk Cr-deposition by pack-cementation for instance may be preferable to do not risk the appearance of brittle TCP phases.

  microstructures of the {0.25 wt.%C, 3.72 wt.%Hf}-containing alloys ↓ the old 25 wt.%Cr containing one ↓ ↓ the new 32.5 wt.% containing one ↓ 32.5 wt.% Cr instead 25 wt.%: no significant changes in the microstructures but major improvement of the resistance against high temperature oxidation! 0.25 wt.%C 25 wt.%Cr 0.25 wt.%C 32.5 wt.%Cr during less than 10 hours; after linear and fast microstructures of the {0.50 wt.%C, 7.44 wt.%Hf}-containing alloys ↓ the old 25 wt.%Cr containing one ↓ ↓ the new 32.5 wt.% containing one ↓


Marc-Alexandre Tareau

Alexander Greene

Guillaume Odonne
email: guillaume.odonne@cnrs.fr

Damien Davy

Ceiba pentandra (Malvaceae) and associated species: Spiritual Keystone Species of the Neotropics 1

Keywords: ethnobotany, Amazonia, Caribbean, lupuna, samauma, mapou, silk-cotton tree, fromager, kapok ethnobotanique, Amazonie, Caraïbes, lupuna, samauma, mapou, capoquier, fromager, kapok

come

Introduction

To anyone living or travelling in most parts of the Neotropics or the Caribbean, it is impossible not to notice a majestic tree, its branches crowded with epiphytes and intermingled lianas, bordering Amazonian streams, emerging from distant hills in Caribbean islands, or simply existing in parking lots in urban areas. Among the 16 000 or so Amazonian tree species [START_REF] Ter Steege | The discovery of the Amazonian tree flora with an updated checklist of all known tree taxa[END_REF], one effectively looms above the rest: Ceiba pentandra (L.) Gaertn. This prominent tree from the Malvaceae (Bombacoideae) family is probably the most wellknown (and widespread) representative of the Ceiba genus, and it is an important cultural spe-cies in the Neotropics. From the perspective of interrog-ating transversalities and cultural hybridizations across human cultures, this species stands at a meeting point, and we decided to explore in depth the relationships between Amazonian, Central American, and Caribbean cultures and the Ceiba tree. As a consequence of differ-ent logics between folk and Linnaean classifications [START_REF] Berlin | Ethnobiological classification: principles of categorization of plants and animals in traditional societies[END_REF], the so called silk-cotton tree that occupies a key place in most cosmovisions ranging from Central America to the Cerrado in Brazil, actually represents a group of several species, some of which are sympatric, and of which the most widespread is Ceiba pentandra. Although this paper mostly focuses on Ceiba pentandra, the others, and their associated local knowledge, are included in this discussion to provide a more global view of the place of these peculiar trees.

The Ceiba genus contains 18 species in the Neotropics, grouped into taxonomic sections Ceiba and Campylanthera [START_REF] Pezzini | Phylogeny and biogeography of Ceiba Mill. (Malvaceae, Bombacoideae)[END_REF]. Except for a few Cerrado species, the majority are large trees, often with spines along the trunk and branches, and frequently with large buttresses. Leaves are palmate with three to seven leaflets. Flowers are actinomorphic, with five petals, red, pink, yellow, or white depending on the species, and from 2 or 3 cm to 15 cm. Ceiba pentandra is the tallest, frequently emerging above the canopy (up to 70 m high) (Fig. 1), and developing large buttresses bearing conical prickles. Flowers are pen-tamerous, small (2-3 cm), white, and its seven-foliolate leaves are glabrous. The fruit is a capsule (12-24 cm long), containing seeds surrounded by long, wooly, non-wettable hairs called kapok [START_REF] Dick | Extreme long-distance dispersal of the lowland tropical rainforest tree Ceiba pentandra L. (Malvaceae) in Africa and the Neotropics[END_REF][START_REF] Mori | Guide to the vascular plants of central French Guiana: Part 2. Dicotyledons, Memoirs of the New York botanical garden[END_REF]. Ceiba spp. range from seasonally dry tropical forests to tropical forests, and from Mexico (North) to Argentina (South)(Fig. 2). Ceiba lupuna P.E.Gibbs & Semir is the only species restricted to rain forests. Ceiba pentandra, Ceiba samauma (Mart. & Zucc.) K.Schum., and Ceiba speciosa (A.St.-Hil.) Ravenna are mostly present in rain forests, whereas the other species are more widespread in seasonally dry for-ests [START_REF] Pezzini | Phylogeny and biogeography of Ceiba Mill. (Malvaceae, Bombacoideae)[END_REF]. Ceiba pentandra is also naturally present in equatorial Africa and naturalized in all the humid tropics after human introduction (https://www. gbif.org/species/5406697) -it originated from the Neotropics and its seeds probably dispersed to Africa by floating over the Atlantic Ocean [START_REF] Dick | Extreme long-distance dispersal of the lowland tropical rainforest tree Ceiba pentandra L. (Malvaceae) in Africa and the Neotropics[END_REF].

Questioning inhabitants about these trees, one rap-idly understands that they bear something unique. We first noticed this through years of fieldwork in collabo-ration with Amazonian and Caribbean peoples, and as we started reviewing the literature about Ceiba spp., it became clear that this species represents a very good example, in this vast region of the world, of a Cultural Keystone Species [START_REF] Garibaldi | Cultural keystone species: implications for ecological conservation and restoration[END_REF]. But unlike most Keystone Species, Ceiba is not an edible plant and is minimally used in medicine, technology, and craft (although kapok fibers have an undeniable technical and economic interest). To better explain the cultural centrality of Ceiba spp., we thus decided to de-velop the concept of a Spiritual Keystone Species to describe the importance of the silk-cotton tree in Neo-tropical cosmovisions.

Materials and methods

A thorough review of our personal Neotropical anthropological and ethnobotanical literature was conducted by searching for all the Linnaean names related "once contained all the water of the world in its bulging trunk and where men obtained fish from one end of the year to the other" (Lévi-Strauss 2009,p. 86).Their Chorote neighbors also believe that all the water in the world and all the fish come from the trunk of the Ceiba chodatii (Hassl.) Ravenna [START_REF] Scarpa | Plantas asociadas a la pesca y a sus recursos por los Indígenas Chorote del Chaco Semiarido (Argentina)[END_REF]). Among the Peruvian Yagua, the lupuna (possibly Ceiba lupuna) is the water tree and the symbol of the axis of the world [START_REF] Chaumeil | le chamanisme chez les Yagua de l'Amazonie péruvienne[END_REF]. A Yagua myth tells how this giant tree was cut down by the two mythical heroes, and as it fell, created the Amazon (the artery of the world whose meanders correspond to the sinuous contours of the trunk and branches), all of its water emptying to form this great river [START_REF] Chaumeil | le chamanisme chez les Yagua de l'Amazonie péruvienne[END_REF]. Other versions of this myth are found in Amazonia and Gomez Gruber (1997) reports that, among the Tikuna, in the beginning only night existed because a large Ceiba obstructed the world and prevented light from entering it. The primordial brothers tried to remove it without success. They called for help from all the animals in the forest but only a small squirrel succeeded in felling the tree so that light could finally appear. The trunk formed the Rio Solimões and its branches the other rivers and creeks. To prevent the tree from growing back, the brothers put a giant tur-tle on the stump to graze on the new shoots. A butterfly took the heart of the tree, which was still beating, and gave it to an agouti that buried it. From the heart grew an umari tree (Poraqueiba sericea Tul. or Poraqueiba paraensis Ducke), which gave birth to the first woman who then married one of the two brothers. Relation to water is also evident for the Kali'na of the Guiana Shield, where the mythical anaconda Alamari, while lying in the canopy of a Ceiba, was so heavy that it broke the branches under it and fell into the river and became the water spirit Okoyumo [START_REF] Ahlbrinck | Encyclopaedie der Karaïben[END_REF]. For the Huaorani from Ecuador, the Ceiba is the primordial tree providing shade, food, and shelter, where all the beings dwelled in the beginning. This tree was bound with a large vine but a little squirrel cut it so that the "Amazon Basin was born from the fallen giant tree, and the many species of fish from its leaves" (Rival 1999, p. 361). Among the Kogi from Colombia: "When the ninth world, the highest world, was being formed, an immense Ceiba tree began to emerge from the pristine sea and around this cosmic axis the four divine brothers built the first temple and called it "alnáua". The Ceiba tree is called "ululá" or is personified by the name of the mythical Máma Zinkala. It was the first tree of Creation. .. A vertical line passing through the tip of the roof, through the centre of the floor and the nadir which -in this case -is the apex of the invisible inverse roof, constitutes the cosmic axis, identified with the spindle rod, with the great Ceiba of Creation, or with the central pole that the Mother placed in the centre of the snow-capped mountains" (Reichel-Dolmatoff 1975, p. 204). The Baniwa of Uaupes share this worldview of a to Ceiba (Chorisia, Bombax etc.), as well as the most com-mon folk names (fromager, lupuna, mapou, paineira, samaúma etc.). Additional literature was gathered from Scopus, J-Stor, and Google Scholar with the same key-words. To this review of the literature, we added notes taken during our own field observations, mostly in Amazonia, the Guiana Shield, and the Caribbean. Lin-nean names were updated according to APG IV (The Angiosperm Phylogeny Group 2016) via the Taxonomic Name Resolution Service [START_REF] Boyle | The taxonomic name resolution service: an online tool for automated standardization of plant names[END_REF].

Results and discussion

A founding and shamanic tree among Indigenous cultures From Central America to the Argentinian Chaco, the genus Ceiba shares a singular place in cosmovisions. The firsts synthetic writings on Indigenous cultures of the Guiana Shield by authors such as [START_REF] Roth | An inquiry into the animism and the folklore of the Guiana Indians[END_REF] and de [START_REF] De Goeje | Philosophy, initiation and myths of Indians of Guiana and adjacent countries[END_REF] showed the cultural importance of this tree. For the Akawaio, Makusi, and Arawak from Guyana, all beings were created from pieces of Ceiba wood or bark that were thrown from the top of a large tree (on land or in the water) by a demiurge, thus creating birds, terrestrial and aquatic beings, as well as men and women [START_REF] De Goeje | Philosophy, initiation and myths of Indians of Guiana and adjacent countries[END_REF][START_REF] Roth | An inquiry into the animism and the folklore of the Guiana Indians[END_REF]. In contrast, the Urubu Ka'apor from Brazil believe that the non-Indigenous people were those created from its wood, whereas they were carved from Handroanthus serratifolius (Vahl) S.O.Grose [START_REF] Balée | Footprints of the forest, Ka'apor ethnobotany: the historical ecology of plant utilization by an Amazonian people[END_REF]. One of the formative clans of the Wayãpi from French Guiana, the "kumakapisuke" ("old beetle larva of the Ceiba tree" in English) are the offspring of an incestuous couple, itself born of insect larvae found in the trunk of a rotting Ceiba [START_REF] Grenand | Dictionnaire wayãpi-français: lexique françaiswayãpi ; (Guyane française), Langues et sociétés d'Amérique traditionnelle[END_REF]. The classic period Maya of Mesoamerica and their modern descendants give this tree a central place in their mythology [START_REF] Freidel | Maya Cosmos: three thousand years on the shaman's path[END_REF][START_REF] Schele | A forest of kings: the untold story of the Ancient Maya[END_REF]). Indeed, "yakché" ("the green tree" in English) is the primordial tree, the axis mundi of the Mayan world, passing through the seven heavens above the Earth and allowing the spirits of the dead to pass from one world to the next to finally reach the eternal abode [START_REF] Tozzer | A comparative study of the Mayas and the Lacandones[END_REF]. As exemplified by [START_REF] Cano | Sacred tree: Ceiba. Mayan Ethnobotany[END_REF], Gua-temalan murals and ceramics from the classic Mayan period widely feature Ceiba trees, and pre-Columbian Mayan incense burners were often represented with Ceiba prickles, probably associating this species to religious and (or) spiritual aspects [START_REF] Zidar | Sacred Giants: Depiction of Bombacoideae on Maya Ceramics in Mexico, Guatemala, and Belize[END_REF]. The Hatx Winik, Lacandones from Chiapas, also see Ceiba as the pillar of the world, the support of the vault of heaven, and the dwelling place of the tree spirits [START_REF] Pérez | Petite encyclopédie maya: l'environnement des Lacandons de Lacanjá (Chiapas, Mexique), Recherches Amériques latines[END_REF].

While in the Chamacoco's view of the universe, Ceiba insignis (Kunth) P.E.Gibbs & Semir (known in Paraguay as "pallo borracho") is a cosmic tree linking the Earth and the sky [START_REF] Sequera | The Tomárâho conception of the sky[END_REF], Lévi-Strauss highlighted in the second volume of his mythological masterpieces that the "yuchan" of the Matako and Chulupies from the Paraguayan and Argentinean Chaco giant Ceiba passing through the different worlds stacked on top of each other, inhabited by different beings [START_REF] Wright | A Joyful Place: Baniwa Jaguar shamans' songs and historical change[END_REF]. [START_REF] Lévi-Strauss | Du miel aux cendres[END_REF] points out that the Mocovi and the Bororo believe the Milky Way to be the ashes of the tree of the world after it was burned down. This is similar to the Wayana cosmovision -their founding demiurge, Kuyuli, and his companion burned a gigantic Ceiba whose ashes became the Milky Way, which means in Wayana "theplacewhere the Ceiba was burned" (Chapuis and Rivière 2003,p.171).Wayana Shamans travel the Milky Way during trance [START_REF] De Goeje | Philosophy, initiation and myths of Indians of Guiana and adjacent countries[END_REF].

Many Amazonian cultures consider this tree to be the vehicle for Shamans to move through the different strata of the world. Thus, as do the Baniwa, the Wayãpi of French Guiana consider Ceiba to be the Shamans' lad-der used to climb and meet their spirit allies [START_REF] Grenand | Pharmacopées traditionnelles en Guyane: Créoles, Palikur, Wayãpi[END_REF]). Indeed, for them, this tree is inhabited by a "kumakaya", a very powerful jaguar spirit that only the most powerful Shamans can domesticate [START_REF] Grenand | Introduction à l'étude de l'univers Wayapi : ethnoécologie des Indiens du Haut-Oyapock (Guyane française), Langues et Civilisations à Tradition Orale[END_REF]. The spirits or metahumans -to use the term pro-posed by [START_REF] Sahlins | On the political economy of the enchanted universe[END_REF] with regard to [START_REF] Descola | Par-delà nature et culture[END_REF] animist ontological scheme -or the mother of this tree, are powerful and linked to the masters of the for-est. Among the Kali'na, dwelling from French Guiana to Venezuela, the Ceiba is considered the "wewe yumu", the father or master of the trees (de Goeje 1943). Of the five types of Shamans, which are defined according to the plant guiding their initiation, there are "takini" (Brosimum acutifolium Huber), chile (Capsicum annuum L.), tobacco (Nicotiana tabacum L.), "kwasini" (Ficus spp.), and "kumaka" Shamans (Ceiba pentandra). The spirits inha-biting "kumaka", like those of the "kwasini", are both beneficial and maleficent, unlike the first three types that are only beneficial. Moreover, according to [START_REF] Gillin | The Barama River Caribs of British Guiana[END_REF],the Ceiba tree is distinguished from other trees by the fact that it harbors many spirits including a par-ticular being that lives only in this tree, the "kumaka akïrï". The number of spirits hosted by it is also the rea-son for its gigantic size and implies that it must not be felled. If someone tries to fell it, the axe will inevitably break. And if in the end they finally manage to cut the tree, the spirits that would escape from it will never be appeased. [START_REF] Ahlbrinck | Encyclopaedie der Karaïben[END_REF] tells a Kali'na myth about how a nine-year-old boy was attracted by the spirit of the "kumaka" and was initiated. He became a very powerful Shaman who was only called for when a person died as he could resurrect them, whereas other Shamans were powerless. The boy used to sleep in this tree and came back to the people only when someone had died.

Ceiba is also considered a link with other spirit plants; for the Kali'na, the anaconda Alamari, who lived at the top of a Ceiba, was so gigantic that it completely covered the branches of this giant tree. It hunted without leav-ing its tree, attracting game with its spells. One day, a young girl collected some white clay at the foot of the Ceiba and smeared it on her garters to whiten them, but it was Alamari's excrement so he became her husband. The villagers opposed this union, set a trap for Alamari, and burned him alive. From his ashes grew the charms "tulala" (Caladium spp.) [START_REF] Ahlbrinck | Encyclopaedie der Karaïben[END_REF]. Alamari is considered the spirit of this tree (and that of the "takini") and controls all Ceiba and other trees' spirits (de Goeje 1943). The Teko from French Guiana similarly consider that if the remains of a giant otter, "tsololo" (Pteronura brasiliensis), are buried at the foot of a "kubaka" (Ceiba pentandra), all sorts of medicinal plants will grow on its rotting body [START_REF] Navet | Savoirs communs et chamaniques sur les plantes médicinales et psychotropes des Indiens Teko (Emérillon) de Guyane[END_REF]. They tell that "in the "kubaka", there can be good and bad spirits. When the tree is beautiful and clean underneath, it means that there are "kaluwat" (good spirits) but when the tree is not beautiful and is dirty underneath, it means that it is inhabited by "baskilili" and "gulupi" (bad spirits)".

For the Tikuna, the master of this tree is the master of the forest or Curupira, Ngo'o in Tikuna [START_REF] Matarezio Filho | Trompetas ticuna de la Fiesta de la Moça Nova[END_REF]. The spirit of the Ceiba is considered to have a black color among the Yagua, Kali'na, and Teko. The Palikur from French Guiana and Brazil use a bath of Ceiba bark during the initiation of Shamans (F. Renoux, personal communication). Similarly, the Yagua make a shamanic initiation cigar from its bark [START_REF] Chaumeil | le chamanisme chez les Yagua de l'Amazonie péruvienne[END_REF]. For the "curanderos" from Huancabamba (Peru), Coleus sp. mixed with Ceiba pentandra, "higiron" (an unidentified species, probably a Ficus sp.), latex of "lechero" (Euphorbia sp.), chili pepper (Capsicum annuum), salt, alcohol, and holy water can kill an enemy (De Feo 1992), whereas the Peruvians of Loreto consider its bark a shamanic poison [START_REF] Roumy | Plant therapy in the Peruvian Amazon (Loreto) in case of infectious diseases and its antimicrobial evaluation[END_REF]). Among the Yanomami, the spirit of the Ceiba is invoked during shamanic treat-ments to scare away evil spirits, and evil substances are dispersed via its cottony fibers [START_REF] Albert | Urihi a: a terra-floresta Yanomami[END_REF]. [START_REF] Bennett | Ethnobotany of the Shuar of Eastern Ecuador[END_REF] describe an Aguaruna myth: "A person clears the plants from the base of a Mente tree (Bombacaeae spp.) and then drinks green tobacco juice until he becomes intoxicated. During a storm the "wiakuch" or soul of the tree comes. "Wiakuch" gives the person magical darts that enable him to become a shaman". Ese-Eja from Peru consider it a "teacher plant" in ayahuasca shamanism and "sorcery with Ceiba spp. causes the swelling of the victim, a condition which on one case was medically diagnosed by hospital workers as water retention through kidney malfunction" [START_REF] Alexiades | Ethnobotany of the Ese Eja: plants, health, and change in an Amazonian society[END_REF].

The Shipibo also attribute a very powerful spirit to Ceiba, which is associated with ayahuasca and brings visions [START_REF] Saavedra | Estudio de la adaptación del chamanismo shipibo-conibo al medio urbano: el caso de Guillermo Arévalo en la ciudad de Pucallpa[END_REF]. When a Shipibo wants to become a Shaman and wishes to know the spirit of this tree, he drinks the bark with tobacco in the morning for six to eight months [START_REF] Childs | A study of religion, culture, and medicinal plants of three South American Indigenous groups[END_REF]). Among the Chorote of Argentina and Paraguay, a shamanic chant linked to the Ceiba tree allows one to meet the drinking water accumulated inside its trunk, and songs also allow the return to claim what he or she considers to be his or hers by right of the contract" [START_REF] Jamieson | Contratos con los dawanka y procesos productivos entre los miskitos de las comunidades costeras de la RAAS[END_REF]. For the Colombian Siona, Ceiba is the most dangerous tree. It has three different classes of "huati" ("invisible spirits" in English): those that live under the roots and scare people by giving them diseases; those that live in the trunk and are located in the buttresses, which some-times appear to hunters to make them get lost; and those that live in the foliage, whose long tongues hang down to catch men passing underneath. If caught, the person will suffer from a disease that causes the tongue to hang out of the mouth. It is therefore not advisable to pass alone under a Ceiba but if you must, you should whistle and smoke a cigarette to protect yourself [START_REF] Langdon | La negociación de lo oculto: chamanismo, medicina y familia entre los Siona del bajo Putumayo[END_REF]. The Kalinago from La Dominique believe that Ceiba shelters spirits that might become angered if disturbed [START_REF] Hodge | The ethnobotany of the island Caribs of Dominica[END_REF].

Along with being considered a Shaman's spirit ally, the Ceiba is connected to death and is sometimes per-ceived as a psychopomp tree. The Chacobo believe that the souls of the dead reside in the trunk of the Ceiba [START_REF] Erikson | El ritual como máquina del tiempo: ejemplos chacobo (Amazonía boliviana)[END_REF]). Among the Maya (Landa), the souls of the dead go to the great green tree ("yakché") to enjoy the coolness of the shady branches, under which they enjoy eternal rest (de Goeje 1943). The Wayana, living in Bra-zil, French Guiana, and Suriname, believe that after death the soul reaches a gigantic tree -the Trios and Guarayos believe this tree is none other than the Ceiba (de Goeje 1943).

A symbolic species among Afro descendants Interestingly, Ceiba pentandra is also omnipresent in the Afro-American magico-religious universe [START_REF] Nossin | Plantes magiques de Martinique, Guadeloupe et des Petites Antilles Emmanuel Nossin[END_REF]. As Hurbon (1940Hurbon ( -1972) ) pointed out, the strong permanence in Haitian voodoo of the attribution of magical properties to the silk-cotton tree is undoubtedly the result of a resonance between beliefs of African ori-gin (the tree is sacred in many West African cultures; Burkill 1995) and the cultural importance of this same species within many Indigenous American cultures (see previous parts). The convergence of these analogous belief systems must have contributed not only to the reinforcement of those of the enslaved Africans and their descendants but also to an interculturalization effect [START_REF] Tareau | Les phytothérapies du littoral guyanais : regard ethnobotanique sur une pharmacopée métissée[END_REF]) that has given rise to reinvented practices that do not appear to be the simple survival of African rituals [START_REF] Price | The birth of African-American culture[END_REF].

In Cuba, Ceiba pentandra is also a major host tree for several "orishas" (including Aggayù, Babà, Iroko, Obatalà, Oddùa, Ogùn, Oko, Olofi, Shangó, Yemayà) and is there-fore the object of a particularly important devotion among a large part of the population following Afro-Cuban cults. According to a widespread syncretic belief in Cuba, which also provides an interesting Christian explanation to the popular sacralization of the tree, the Virgin Mary and the infant Jesus took refuge in a cavity of a silk-cotton tree that then closed and grew thorns to Shaman to use the trunk as a "jail of souls" [START_REF] Scarpa | Plantas asociadas a la pesca y a sus recursos por los Indígenas Chorote del Chaco Semiarido (Argentina)[END_REF]). Among the Amazonian Mestizo populations of Peru, the spirit of this tree is considered very dangerous and acts as a sorcerer and can kill people who do not fol-low the required recommendations [START_REF] Luna | Vegetalismo: shamanism among the mestizo population of the Peruvian Amazon[END_REF]). This author states that among the Shipibo of Peru, the spirit of this tree is the supreme spirit or chief of the forest and of the spirits of the other trees, and also the chief spirit of the Shipibo Shaman [START_REF] Saavedra | Estudio de la adaptación del chamanismo shipibo-conibo al medio urbano: el caso de Guillermo Arévalo en la ciudad de Pucallpa[END_REF]. It is con-sidered to be the rain tree, and rituals are held near it to beg for rain, further reinforcing the link between Ceiba and water. Among the Shipibo and Conibo, [START_REF] Tournon | Magia, brujería, chamanismo, plantas y enfermedades[END_REF] says that the Ceiba can "cutipar", meaning if a fa-ther cuts the tree down his son will be bewitched and suffer from swelling of the belly. The remedy consists of bathing in a decoction of bark from the same tree. Among the Tacana of Bolivia, Ceiba's spirits can cause "mal viento" [START_REF] Dewalt | Ethnobotany of the Tacana: Quantitative inventories of two permanent plots of Northwestern Bolivia[END_REF]. The Sumu Ulwa of Honduras also believe that a powerful spirit inhabits this tree [START_REF] Coe | Ethnobotany of the Sumu (Ulwa) of southeastern Nicaragua and comparisons with Miskitu plant lore[END_REF]. The Shawi in the Peruvian Amazon fear this tree because of the spirits it hosts. They are said to turn around its canopy at night, whistling, and it is advised not to stay nearby. Among the Yagua of Peru, the mother of the Ceiba is very power-ful and the Shamans use it to deprive victims of their vital principles and drive them mad by subtracting their spirit and causing their stomach to swell. This mother of the Ceiba has either the form of a snake (like the Kali'na), an earthworm, or a human, and its color is black [START_REF] Chaumeil | le chamanisme chez les Yagua de l'Amazonie péruvienne[END_REF].

Moreover, the ability of this tree to move is regularly mentioned in the literature. The Arawak of Guyana believe that it moves nightly and returns to its place afterwards, this ability being due to the spirit that inhabits it [START_REF] Roth | An inquiry into the animism and the folklore of the Guiana Indians[END_REF]. For [START_REF] Dance | Chapters from a Guianese log-book, or the folk-lore and scenes of sea-coast and river life in British Guiana; comprising sketches of Indian, Boviander, and Negro life[END_REF], the guardian spirit of this tree "walks around the tree at mid-day and at mid-night". According to the Yaminawa, the Ceiba is the house of Xuba, a strong and aggressive being that can cause illness to whoever passes by or whoever tries to cut it down without taking the proper precautions, and Xuba is especially harmful to parents with newborn children as the spirit of the tree can borrow the soul of the child [START_REF] Gillin | Cuerpos en transformación: sobre la noción de persona y el control alimentar entre los Yaminawa[END_REF]). Among the Miskito, dwelling from Honduras to Nicaragua, the Ceiba spirit called Sisin Dawanka can offer individuals wealth, success with members of the opposite sex, misfortune for their ene-mies, and so on: the supplicant has only to approach a Ceiba tree where the "dawanka" is supposed to live and a door will open in the tree to admit him or her. At that moment the deal begins. The "dawanka" may grant the supplicant a major request but usually asks for pay-ment. For example, he or she may grant the supplicant his or her wish with the understanding that he or she will later claim his or her first child, an aspect of the contract that the human participant, in his or her greed, may not take into account. Later, the "dawanka" may protect them [START_REF] Pesoutova | Indigenous ancestors and healing landscapes: cultural memory and intercultural communication in the Dominican Republic and Cuba[END_REF]. According to [START_REF] Cabrera | La Forêt et les Dieux. Religions afrocubaines et médecine sacrée à Cuba[END_REF], "the dead, the ancestors, the African "saints" of all the African nations that came to Cuba and the Catholic saints go to this tree and inhabit it permanently" (p. 166). The tree, which in Cuba is also never cut down, is called "iroko" by the Afro-Cubans, in memory of the tree revered throughout the Guinea coast, Milicia excelsa (Welw.) C.C.Berg, also called "iroko" in western Africa [START_REF] Quiroz | Do not fear the supernatural!: The relevance of ritual plant use for traditional culture, nature conservation, and human health in western Africa[END_REF][START_REF] Quiroz | The cultural importance of plants in Western African religions[END_REF]. In addition, in the mythological representations of Afro-Cuban Santeria, Iroko is also the name given to an important "orisha" whoisbelieved tolivein the trunk of theCeiba tree in the company of his wife Aboman [START_REF] Cabrera | La Forêt et les Dieux. Religions afrocubaines et médecine sacrée à Cuba[END_REF].

Called "mapou" or "pye mapou", probably an apocope of the common Kongo name "mapouata" (Nossin 2019, citing Durand and[START_REF] Durand | Les noms de famille d'origine africaine de la population martiniquaise d'ascendance servile: et autres survivances africaines en Martinique (seconde édition revue et enrichie)[END_REF] in Haitian Creole, Ceiba is arguably the most revered plant species in Haitian voodoo (Hurbon 1940(Hurbon -1972)). Indeed, this tree serves as the residence ("repozwa" or "kay lwa" in Haitian Creole) of several spirits ("lwa") of the Haitian voodoo pantheon, particularly those of the Gede [START_REF] Tarter | Trees in Vodou: An arbori-cultural exploration[END_REF], who are the "lwa" of death [START_REF] Marcelin | Les grands dieux du vodou haïtien[END_REF]. According to several testimonies collected from Haitian voodooists, it is also home to the "lwa" called Agarou, who is the god of the wind and the storm, Loko (probably by borrowing another vernacular name of the species M. excelsa, "loko" in Fon), who is the god of trees and forest, and Erzili, who is the goddess of fertility [START_REF] Marcelin | Les grands dieux du vodou haïtien[END_REF]. For this reason, it regularly receives offerings and libations, and scarves, candles, and images in the symbolic colors of the "lwa" associated with Ceiba are regularly attached to its branches or trunk (Fig. 3). Luck baths ("ben chans")arecommonly taken near the tree by practitioners who hope to attract the favor of the spirits it shelters. In addition, its status as a sacred tree means that it is almost never cut down for fear of divine reprisals that could fall on those who commit this act, unanimously considered as sacrilege [START_REF] Séverin | Plant ak pyebwa tè d Ayiti[END_REF]. A Haitian man residing in Cayenne, French Guiana explained that "mapou is the cathedral of voodoo. The Catholics put candles in the chapels, we put ours on its trunk. So cutting down a mapou tree, for a voodooist, is like destroying a church for a Christian. It is a serious sin".

Among the Aluku Maroons of French Guiana, the seedling is used to strengthen babies [START_REF] Fleury | Busi-Nenge, les hommes-forêt: Essai d'ethnobotanique chez les Aluku (Boni) en Guyane française[END_REF]. The spirits related to the supreme god Papa Gadu (or Voodun) as well as Ampuku, the spirit of the forest, reside in this tree called "kankantii" (by deformation of the English "cotton tree") and may be incarnated in the red-tailed boa (Boa constrictor, which is called "daguwe", from the Dahomean "dãgbe", an Ewe-Fon word also used to desig-nate a sacred snake; Herskovits and Herskovits 1936). However, unlike the Caribbean and French Guianese Creoles who do not hesitate to plant it (some silkcotton trees are even enchanted -"monté" in French Caribbean Creole) to protect a plot of land against evil spirits and promote their owner's luck [START_REF] Benoît | Corps, jardin, mémoires, Anthropologie du corps et de l'espace à la Guadelope[END_REF][START_REF] Vilayleck | Ethnobotanique et médecine traditionnelle créoles[END_REF]), the species is avoided around the homes of the Maroons. Although, paradoxically, several Maroon villages are characterized by a giant silk-cotton tree overhanging and "protecting" them, French Guianese Maroons believe that it can carry evil entities. Thus, we can probably argue -to use the image formulated by [START_REF] Price | The birth of African-American culture[END_REF] -that the same symbolic container (the sacralization of Ceiba pentandra) has spread within several Afro-descendant cultural groups, but that their particular histories have forged different contents (the beneficial or maleficent "nature" of this species). In any case, as early as 1890, the explorer- missionary Verschuur reported the "kankantii" tree as the most venerated tree of the Maroons of French Guiana [START_REF] Verschuur | Voyage aux trois Guyanes et aux Antilles[END_REF] and contemporary testimonies confirm this idea: "the "kankantii" is like a lightning rod, it attracts evil spirits. It shelters both the good and the bad ones. .. the Ampuku spirit lives in the big "kankantii", that's why we don't cut it down or burn it. We put beers at its foot for them. It is also where we make music for the "obia" [spirits]. People also bathe under the "kankantii" for good luck, but if you use its leaves or bark to make remedies, you have to pay him with beer and rum. If someone is possessed, they are bathed under the "kankantii" so that the Ampuku spirit in the person returns home", explained a Saamaka man living in Matoury, French Guiana. Some healing houses are nevertheless located at the foot of large silk-cotton trees to allow the medico-magical rituals to be more effective thanks to the nearby deities present in the tree (Fig. 4).

In the other Creole societies of the Caribbean and the Guiana Shield where Afro-descendant religious her-itage is less institutionalized than in the previous cases, some survivals must nevertheless draw our attention to the persistence of a certain religiosity around Ceiba pentandra. This treeis a dwelling placefor African spirits in Venezuela [START_REF] Pollak-Eltz | Vestigios africanos en la cultura del pueblo venezolano[END_REF]. In Martinique [START_REF] Nossin | Plantes magiques de Martinique, Guadeloupe et des Petites Antilles Emmanuel Nossin[END_REF][START_REF] Vilayleck | Ethnobotanique et médecine traditionnelle créoles[END_REF], Guadeloupe [START_REF] Benoît | Corps, jardin, mémoires, Anthropologie du corps et de l'espace à la Guadelope[END_REF], French Guiana (Ribal-Rilos 2004), Suriname (van Andel 2010; van Andel and Ruysschaert 2014) and in the Dominican Republic [START_REF] Pesoutova | Indigenous ancestors and healing landscapes: cultural memory and intercultural communication in the Dominican Republic and Cuba[END_REF], it would not occur to an inhabitant to cut down this tree, which allows it to survive in the urban space where it sometimes remains isolated amongst buildings (Fig. 5).

In the same way, many people continue to venerate the tree in a clandestine way, talking to it to ask for advice or courage or lighting a candle at its foot in honor of the deceased or in search of luck. The Martinican poet Césaire himself regularly visited a silk-cotton tree, the only tree to survive Mount Pelée's eruption in 1902 [START_REF] Nossin | Plantes magiques de Martinique, Guadeloupe et des Petites Antilles Emmanuel Nossin[END_REF]). This devotion is, however, mixed with fear as Ceiba pentandra is considered "the devil's tree par excellence", housing potentially dangerous spirits such as "soukouyans" or "soukliyan" (flying entities that, like vampires, suck the blood of their victims) in the French West Indies [START_REF] Leti | L'univers magico-religieux antillais: ABC des croyances et superstitions d'hier et d'aujourd'hui[END_REF]or "jumbies" and (or) "duppies" in Jamaica [START_REF] Corzani | West Indian mythology and its literary illustrations[END_REF][START_REF] Keegan | Talking Taíno: Caribbean natural history from a native perspective[END_REF].

If it is true that these magical attributes are sometimes transversal to the shamanistic properties mentioned previously within many Amerindian communities, they are also linked to uses found in Africa. Indeed, Burkill notes that it is the most important fetish tree in many West African cultures and that, for example, in the Suda-nian region it is considered to be inhabited by the divine python [START_REF] Burkill | The useful plants of west tropical Africa[END_REF]. Herskovits also notes that in the for-mer Dahomey, the silk-cotton trees are revered because the souls of ancestors have taken their residence in them, likewise among the Ndjuka from Suriname [START_REF] Herskovits | Suriname folklore[END_REF].

Medicinal uses

Alongside the properties of Ceiba in shamanistic heal-ing, some phytotherapeutical uses, although much less numerous, can also be noted throughout its distribution. Among these, the most common are as a diuretic, analgesic, or for healing wounds. The species is used for waist pains and as a diuretic among the Pilaga of Chaco [START_REF] Filipov | Medicinal plants of the Pilagá of Central Chaco[END_REF]). Among the Ayoreo, from Chaco as well, the plant is employed to cure open wounds [START_REF] Renshaw | The effectiveness of symbols" Revisited: Ayoreo Curing Songs[END_REF]. Some observation of its use against leishmanial external lesions were made among the Wayãpi [START_REF] Odonne | Treatment of leishmaniasis in the Oyapock basin (French Guiana): A K.A.P. survey and analysis of the evolution of phytotherapy knowledge amongst Wayãpi Indians[END_REF]) and the Ashuar [START_REF] Giovannini | Medicinal plants of the Achuar (Jivaro) of Amazonian Ecuador: Ethnobotanical survey and comparison with other Amazonian pharmacopoeias[END_REF] who apply the ground bark directly. This last application is also noted among the Kallawaya in the treatment of tetanic wounds [START_REF] Girault | Kallawaya, guérisseurs itinérants des Andes: recherches sur les pratiques médicinales et magiques[END_REF].

Among the latter community, the decoction of the flow-ers is applied to the temples and forehead to treat head-aches [START_REF] Girault | Kallawaya, guérisseurs itinérants des Andes: recherches sur les pratiques médicinales et magiques[END_REF]. Similarly, the infusion of flowers is drunk to relieve headaches in Venezuela [START_REF] Delascio-Chitty | Algunas plantas usadas en la medicina empírica venezolana[END_REF], and in Guadeloupe when a child is teething, the child is given a mouthwash with a decoction of Ceiba leaves mixed with soursop leaves (Annona muricata L.) and Bidens sp. leaves [START_REF] Bougerol | Le cumul magico-religieux à la Guadeloupe[END_REF]. In Martinique, ground fresh leaves are used in capillary massages for baldness, and the root bark is drunk as a depurative decoction [START_REF] Ouensanga | Plantes médicinales et remèdes creoles[END_REF]). Among the Amazonian "ribeirinhos", the sap is a remedy against conjunctivitis and the bark is used as an antidiarrheal and diuretic [START_REF] Silva | Nomes vulgares de plantas amazônicas[END_REF]. Finally, in the Saint Lucian community of French Guiana, the ground bark of the trunk is used in the composition of a plaster used to heal broken limbs [START_REF] Tareau | Les phytothérapies du littoral guyanais : regard ethnobotanique sur une pharmacopée métissée[END_REF].

The astringent mucilage contained in the bark is also used in other parts of the world. For example, a bark decoction is used as mouthwash in Senegal and Liberia, and for febrifuge in Nigeria [START_REF] Burkill | The useful plants of west tropical Africa[END_REF].

Technical uses

One of the best known technical uses of Ceiba pentandra in Amazonia is the use of its cottony stuffing or kapok -a term derived via the Dutch from the Malay "kapuq", which refers to the fibers surrounding the seeds [START_REF] Couplan | Dictionnaire étymologique de botanique: comprendre facilement tous les noms scientifiques, La bibliothèque du naturaliste[END_REF]. Indeed, among all Amazonian peoples using blowpipes for hunting or warfare, these cottony fibers are used as a stuffing attached to blowgun darts to form a pressure seal and airfoil. This use was observed among many cultural groups: Siona [START_REF] Vickers | Useful plants of the Siona and Secoya Indians of Eastern Ecuador[END_REF], Matis [START_REF] Erikson | La griffe des aïeux: marquage du corps et démarquages ethniques chez les Matis d'Amazonie, Langues et sociétés d'Amérique traditionelle[END_REF], Huaorani [START_REF] Davis | The ethnobotany of the Waorani of Eastern Ecuador[END_REF], Shuar [START_REF] Bennett | Ethnobotany of the Shuar of Eastern Ecuador[END_REF], Yagua [START_REF] Chaumeil | le chamanisme chez les Yagua de l'Amazonie péruvienne[END_REF], Nikak [START_REF] Mahecha | Recolectando en el Cielo: elementos del manejo nI -kak del mundo (amazonia Colombiana)[END_REF], etc. Etymologically, this use can be identified in the Shuar word for Ceiba, "wampuish", whichstems from the term "wampúch" and means "little weigh" [START_REF] Bennett | Ethnobotany of the Shuar of Eastern Ecuador[END_REF]. It can also be identified in the Siona word "huo yui", which means "blowgun cotton" [START_REF] Vickers | Useful plants of the Siona and Secoya Indians of Eastern Ecuador[END_REF], and in the English common name for Ceiba, silk-cotton tree. Siona people used the seed as a fish bait [START_REF] Vickers | Useful plants of the Siona and Secoya Indians of Eastern Ecuador[END_REF]. Kapok was used industrially until after the Second World War because it was considered to be high quality, insulating, and moisture resistant [START_REF] Correa | Dicionário das plantas úteis do Brasil[END_REF][START_REF] Zeven | Outlines of perennial crop breeding in the Tropics, Miscellaneous Papers 4[END_REF]). Kapok has since been dethroned by synthetic fibres, though the world's leading producers of kapok are still Indonesia and Thailand, which pro-duced almost all the world's kapok with 101 300 tonnes in 20132 . Before the Second World War, the kapok tree was an important commercial crop because its fibers were used extensively in life-jackets and life-belts, in clothing for aviation, as a mattress and cushion-filling material, and in noise insulation for aircraft [START_REF] Zeven | Outlines of perennial crop breeding in the Tropics, Miscellaneous Papers 4[END_REF]. In Brazil, as in Guyana and Mexico, kapok was used for pillows and mattresses [START_REF] Cano | Sacred tree: Ceiba. Mayan Ethnobotany[END_REF][START_REF] Silva | Nomes vulgares de plantas amazônicas[END_REF][START_REF] Van Andel | Non-timber forest products of the North-West district of Guyana[END_REF].

Another important and nearly universal use is that of its wood, which is particularly soft and light. Before the spread of mechanical tools, this wood was widely used to make large canoes (in former Dahomey, this tree was tree during full moon nights [START_REF] Leti | L'univers magico-religieux antillais: ABC des croyances et superstitions d'hier et d'aujourd'hui[END_REF]. This descrip-tion is perhaps due to the numerous bats that contrib-ute to the pollination process of the species [START_REF] Gribel | Flowering phenology and pollination biology of Ceiba pentandra (Bombacaceae) in Central Amazonia[END_REF][START_REF] Lobo | Effects of pollination by bats on the mating system of Ceiba pentandra (Bombacaceae) populations in two tropical life zones in Costa Rica[END_REF].

Several traits of the Ceiba are evoked within African American cultures to attest to the magical nature of this tree. According to [START_REF] Van Andel | What makes a plant magical? Symbolism and sacred herbs in Afro-Surinamese Winti rituals[END_REF],in the emic representations of the Ndjuka from Suriname and French Guiana, one of the proofs of its divine power is that many animals and plants (epiphytes) find refuge on its branches. Moomou (2013, p. 422) notes that "the "kankantii" is also feared because of its gigantism. Indeed, it is the largest tree in the forest, which. .. is necessarily home to deities". This last point is also stressed by [START_REF] Tarter | Trees in Vodou: An arbori-cultural exploration[END_REF] in Haiti, where the physical enormity of this species, as well as its immutability, are singularities often designated to explain its magical character. Moreover, its capacity to remain immutable through time would also explain its resistance to climatic hazards (hurricanes, lightning), which according to [START_REF] Cabrera | La Forêt et les Dieux. Religions afrocubaines et médecine sacrée à Cuba[END_REF], is regularly mentioned by Afro-Cubans to justify the mystical properties commonly attributed to it. Furthermore, as in many Indigenous cultures, it appears that several Afro-descendant communities con-sider the silk-cotton tree as a sort of mediating antenna between humans and the gods [START_REF] Small | The sacred silk-cotton tree: an investigation into the folklore, origins, biology and distribution of the silk-cotton tree[END_REF].

Métraux notes that in Haiti, the large "mapou" move at night to visit each other and terrorize travelers on the roads, with their branches like long arms (Marcelin and Métraux 1947, p. 144), a belief also found in Jamaica in the 19th century [START_REF] Rashford | The cotton tree and the spiritual realm in Jamaica[END_REF]. This point highlights one of the characteristics of the notion of "tree agency", which was developed by [START_REF] Jones | Non-human agencies: trees in place and time[END_REF],namely the recognition of anthropomorphic qualities in Ceiba trees.

Finally, one of the most common biocultural justifica-tions for the magical power widely devoted to this plant species in African-American societies is the regular pres-ence of springs or streams where it grows [START_REF] Séverin | Plant ak pyebwa tè d Ayiti[END_REF]. Indeed, generally preferring alluvial soils [START_REF] Small | The sacred silk-cotton tree: an investigation into the folklore, origins, biology and distribution of the silk-cotton tree[END_REF], Ceiba pentandra is often accompanied by this vital and fundamentally determining element in the cultural designation of plants considered magical [START_REF] Nossin | Plantes magiques de Martinique, Guadeloupe et des Petites Antilles Emmanuel Nossin[END_REF][START_REF] Van Andel | What makes a plant magical? Symbolism and sacred herbs in Afro-Surinamese Winti rituals[END_REF]. Moreover, the medico-magical therapy of Haitian voodoo recommends taking protective plant baths in the streams that flow near the "mapou" [START_REF] Tareau | Les phytothérapies du littoral guyanais : regard ethnobotanique sur une pharmacopée métissée[END_REF].

As Roe wrote, it "is an "anomalous" tree because its trunk is bulbous, rather than straight, and hollow rather than solid. Moreover, it is soft, rather than hard, and light in weight, rather than heavy, the normal char-acteristics of trees. It is also significant that it bears water in its interior. The whole tree is like some sort of curious fruit with its aqueous interior and bulbous shape" (Roe 1982,p. 141).

known as "the tree of the canoes"; [START_REF] Burkill | The useful plants of west tropical Africa[END_REF]. Pre-Columbian peoples, in the absence of iron tools until 1492, preferred easy-to-carve wood for their dugout canoes, and it is sometimes asserted that the West In-dies were settled from Venezuela using Ceiba canoes [START_REF] Bernand | Histoire des peuples d'Amérique[END_REF]). This use is found among the Taino and the Caribs from Martinique [START_REF] Breton | Dictionnaire caraïbe français[END_REF], but also among contemporary Jamaicans, the Tsimane (Reyes-García 2001), the Payas of Honduras [START_REF] Lentz | Medicinal and other economic plants of the Paya of Honduras[END_REF], and the Maya of Yucatan [START_REF] Cano | Sacred tree: Ceiba. Mayan Ethnobotany[END_REF]. The Warao used this tree to make canoes that could carry up to 80 people [START_REF] Roth | An inquiry into the animism and the folklore of the Guiana Indians[END_REF]. One of their myths, the story of Haburi (their civilizing hero), tells how he built a canoe out of wax, then out of clay, then out of different kinds of wood, but all these canoes were stolen by ducks and only the one made out of Ceiba was not stolen [START_REF] Roth | An inquiry into the animism and the folklore of the Guiana Indians[END_REF]. Puerto Rico even made the Ceiba its national tree in memory of its importance as a material for dugout canoes [START_REF] Shearn | Canoe societies in the Caribbean: Ethnography, archaeology, and ecology of precolonial canoe manufacturing and voyaging[END_REF]. Some groups such as the Yano-mami made containers for their plantain puree (an important preparation in death ceremonies, the use of Ceiba pentandra may not be coincidental) [START_REF] Albert | Urihi a: a terra-floresta Yanomami[END_REF] and among the Piaroa, these canoes were used for cassava beer in Jurupari ceremonies [START_REF] Mansutti Rodríguez | Warime Piaroa: cuatro performances en un rito[END_REF]. The Shuar also used the buttresses of the Ceiba to make shields (Bennett et al.2002). Uniquely, the Wayana use its buttresses to carve their wheel-of-the-ceiling or "maluwana", a painted wooden circle attached at the top of their round collective house, the "tukushipan". This "maluwana", decorated around its perimeter with triangles representing the thorns of the trunk of Ceiba pentandra, is painted black and numerous monstrous and metamorphic aquatic beings, the "ïpo", are drawn on it [START_REF] Duin | Wayana socio-political landscapes: multiscalar regionality and temporality in Guiana[END_REF]). This object is culturally important because it protects the building on which it is placed. Nowadays, these "maluwana", which are still used on "tukushipan", are the object of a growing art trade and provide a living for several craftsmen.

Its wood, considered good for cellulose, was overex-ploited in Peru in the 1970s and 1980s to make plywood: five factories were dedicated to plywood production in the late 1970s [START_REF] Gentry | Where have all the Ceibas gone? A case history of mismanagement of a tropical forest resource[END_REF]. Moreover, [START_REF] Descola | La nature domestique symbolisme et praxis dans l'écologie des Achuar[END_REF] mentions that the Ashuar have long sold Ceiba driftwood logs to the Spanish.

What makes Ceiba magical?

In regards to Amazonian cultures, there is an obvious and direct relationship between kapok, hunting darts, and spiritually propelled shamanic darts, allowing anthro-pologists to draw attention to the agency of the fibers of this culturally significant tree [START_REF] Chaumeil | le chamanisme chez les Yagua de l'Amazonie péruvienne[END_REF]. The sharp, spiny thorns on its lower trunk can be compared with shamanic darts and its size can be correlated with the enormous power of it spirit. The inhabitants of the Lesser Antilles believe that the silk-cotton tree is the refuge of the "volan" or "soukouyans", vampire-like fly-ing evil creatures that would turn around the top of the Defining Spiritual Keystone Species

The widespread significance of Ceiba pentandra among Amazonian, Caribbean, and West African peoples, and the strong correlations and overlaps in beliefs and prac-tices connected to it (sheltering spirits, shamanic po-tency, mythic snake, origin of the waters, creation) can be understood as an expression of the world tree or axis mundi concept as expressed by [START_REF] Eliade | Patterns in comparative religion[END_REF]. The tree at the center of the world, which connects the upper and lower realms and defines the vertical dimension of space with its trunk and the horizontal dimension with its roots and branches, is a foundational concept for many cultures and has been associated with a wide range of different tree species. The process by which the symbolic world tree is identified with a Linnean species is nat-urally dynamic, as it is subject to processes of cultural exchange, transformation, and hybridization. For exam-ple Yggdrasil, the world tree of the Norse, is generally identified as an ash tree (Fraxinus excelsior L.) but some-times also with the yew (Taxus baccata L.) [START_REF] Hooke | The sacred tree in the belief and mythology of England[END_REF]). The dynamic nature of the process of sacralization of spe-cific trees is particularly notable with Ceiba pentandra, in part because of the application of the common name ceiba to the related Bombax ceiba L., which is also a sacred species in its natural range in Asia [START_REF] Fowler | The ecological implications of ancesral religion and reciprocal exchange in a sacred forestin Karendi (Sumba, Indonesia)[END_REF][START_REF] Jain | Myths, traditions and fate of multipurpose Bombax ceiba L. -An appraisal[END_REF]). This appears to have facilitated the sacralization of Ceiba pentandra in areas where the two species both occur, for instance in India [START_REF] Chauhan | Worship and trees in India[END_REF], through a process of cultural hybridization similar to that which has taken place in Amazonia and the Caribbean.

The physical and mythological centrality of species like Ceiba pentandra and Bombax ceiba make them perfect candidates for Cultural Keystone Species as defined by Garibaldi and Turner according to a set of six core crite-ria [START_REF] Garibaldi | Cultural keystone species: implications for ecological conservation and restoration[END_REF]. Ceiba trees meet four of these criteria remarkably well (intensity and multiplic-ity of use, linguistic evidence, role in rituals, persistence in cultural memory), so it is not surprising that Ceiba pentandra is sometimes identified as flagship species [START_REF] Anderson | Nature, culture and big old trees: human relationships with Ceiba (Ceiba pentandra) and Live Oak (Quercus virginiana) in the landscapes of Guatemala and Louisiana[END_REF][START_REF] Bowen-Jones | Identifying appropriate flagship species: The importance of culture and local contexts[END_REF]. How-ever, Ceiba trees do not match well with the criteria of "unique position within a culture/irreplaceability" because of the fluidity of belief and practice in relation to the different Ceiba species. They also do not play a central economic role in most cultures to which they are important, so the degree that they "contribute to resource acquisition" is minimal or at least irregular.

The concept of Cultural Keystone Species was origi-nally an adaptation [START_REF] Platten | The cultural keystone concept: Insights from ecological anthropology[END_REF]of the Keystone Species concept of ecology [START_REF] Paine | A note on trophic complexity and community stability[END_REF]. It has been applied to a diverse range of culturally important flora and fauna, from rice in the Phillipines [START_REF] Zapico | Upland rice: cultural keystone species in a Philippine traditional agroecosystem[END_REF] to bears in Canada [START_REF] Clark | Grizzly and polar bears as nonconsumptive cultural keystone species[END_REF]), echidnas in Australia (McKemey et al. 2019), medicinal plants in French Guiana [START_REF] Tareau | Phytotherapies in motion: French Guiana as a case study for cross-cultural ethnobotanical hybridization[END_REF], and herring on the Pa-cific coast of North America [START_REF] Moss | The nutritional value of Pacific herring: An ancient cultural keystone species on the Northwest Coast of North America[END_REF]. Modifications of the original concept have included combining it with the concept of biocultural diversity, arguing that Biocultural Keystone Species better captures the diverse range of eco-logical and cultural significance such species often hold [START_REF] Shackleton | Non-timber forest products as ecological and biocultural keystone species[END_REF]. It hasalsobeenexpandedtothings beyond the level of "species" such as Cultural Keystone Places [START_REF] Cuerrier | Cultural Keystone places: conservation and restoration in cultural landscapes[END_REF] and Cultural Keystone Food Groups [START_REF] Taylor | Culinary cultural conservation and cultural keystone food groups: concepts in ethnobotany[END_REF]. Recent critiques of the concepthavepointed outthat, untilnow, ithas been applied in a largely qualitative fashion and little has been done to further revise the metrics originally proposed in [START_REF] Garibaldi | Cultural keystone species: implications for ecological conservation and restoration[END_REF] (Coe andGaoue 2020a, 2020b).

In light of the continuing utility of the Cultural Key-stone Species concept, we propose a refinement of the term that better captures the cultural centrality of Ceiba pentandra and related species -Spiritual Keystone Spe-cies. As their essential nature is immaterial, Spiritual Keystone Species do not need to aid in resource acquisi-tion, so this criterion is discarded. Given the exchanges and correlations of practices between different cultures around different Bombacoideae species, the criteria of irreplaceability is also discarded. Indeed, Ceiba pentandra is one (the pre-eminent, but still only one) of numerous species that can host different kinds of spirits in many Neotropical ontologies; the mutability of identity of the "Ceiba tree" is related to the fact that the spirits inhabit-ing it can themselves inhabit other trees or beings. It is possible that Spiritual Keystone Species, as opposed to Cultural Keystone Species, are actually more likely to morph over time as the same unit of cultural meaning becomes applied to different species that share the same spiritual qualities. Instead of the criteria of irreplaceability and resource acquisition, we propose the adoption of two new criteria: the presence of culturally derived beliefs, rules, or taboos that regulate contact with the species; and the attribution of magical efficacy or the ability to mediate between humans and spirits, deities, or divine realms.

The Bombacoideae trees are an excellent example of Spiritual Keystone Species given their widespread cen-trality in spiritual practices and the presence of numer-ous taboos against cutting or injuring them. Another classic example of a Spiritual Keystone Species is Ficus religiosa L. (and related species), which is similarly protected by taboos against cutting it down and is sa-cred to Buddhists as the Bodhi Tree, under which Buddha attained enlightenment, and to Hindus as a manifestation of Vishnu [START_REF] Jain | Divine botany-universal and useful but under explored traditions[END_REF]. The baobabs in Africa (Adansonia spp.) (Marie et al.2009), the ash [START_REF] Dumont | The ash tree in Indo-European culture[END_REF] and the yew in Europe [START_REF] Hageneder | Ancient trees and their social recognition: Taxus baccata L. Yew and ancient kingship rituals -European traditions and their Anatolian roots[END_REF][START_REF] Hooke | The sacred tree in the belief and mythology of England[END_REF], and Araucaria spp. in Chile [START_REF] Herrmann | Indigenous knowledge and management of Araucaria araucana forest in the Chilean Andes: implications for native forest conservation[END_REF] are further examples of trees that are Spiritual Keystone Species, whereas the jaguar (Panthera onca) in Amazonia [START_REF] Shepard | Old and in the way: Jaguar transformation in Matsigenka. South Peru Panel View Project Sign, Substance, and Sensation: A Sensory Ecology of Shamanic Plants in Indigenous Amazonia View Project[END_REF], the Asian elephant (Elephas maximus) in south and southeast Asia [START_REF] Ramanathapillai | A forest ride on wild elephants: the philosophy of wilderness in Buddhism[END_REF], and the reindeer (Rangifer tarandus) in Siberia Originally published in Botany 100: 127-140 (2022) dx.doi.org/10.1139/cjb-2021-0099 [START_REF] Vitebsky | What is a reindeer? Indigenous perspectives from northeast Siberia[END_REF] could be considered exam-ples of animals that are Spiritual Keystone Species.

It is important to note that although there are often many sacred species [START_REF] Pungetti | Sacred species and sites: dichotomies, concepts and new directions in biocultural diversity conservation[END_REF]) that likely fulfill some of the criteria laid out here, only a few of these species generally meet all the criteria and thus consti-tute true Spiritual Keystone Species. There are also important differences with "sacred trees" and "sacred groves" because individual trees are sometimes consid-ered sacred while the species to which they belong is not. Perhaps the most striking difference between the Spiritual Keystone Species approach and other concep-tions of Keystone Species is that the sacred species is in fact an ethnospecies and the mutability of its applica-tion to different Linnean species is a significant indica-tor of its immaterial cultural function. An excellent example of this mutability is the use of both silver sage (Salvia argentea L.) and the botanically unrelated sage-brush (Artemisia spp.) as purifying plants falling under the same common conceptual category of "sage", a poten-tial Spiritual Keystone Species in parts of North America [START_REF] Paldam | White sage, bears, and territory: contemporary indigenous religion among the Chumash[END_REF].

Conclusion

Although much had been said in anthropological and (or) ethnobiological monographs about Ceiba spp. in the Neotropics, a comprehensive review has been lacking. This review provides an understanding of the central place that Ceiba pentandra and associated species share through most of the cosmovisions from the cultural groups present in their distribution range. Axis mundi, related with water and water spirits, psychopomp, or associated to shamanistic practicesthese aspects are all much related to the spiritual realm. If this can be explained by particular traits such as its incredible size, rapid growth, conspicuous thorns, seasonal defoliation pattern, and bat pollination, the fact that this tree's perception is shared by so many cultures including Indigenous, Afrodescendant, and West African, is uncom-mon. Spiritual Keystone Species such as Ceiba pentandra are likely to be culturally specific, but this one stands as a common thread for almost all Neotropical and Carib-bean cultures, making it probably the most emblematic species of its range. The concept of Spiritual Keystone Species needs to be further explored and refined, notably through a worldwide review of what species fall within its definition.

Fig. 1 .

 1 Fig. 1. Ceiba pentandra emerging from the morning fog along the Lawa River in French Guiana © Guillaume Odonne.

Fig. 2 .

 2 Fig. 2. Distribution maps of the American and African range of Ceiba pentandra (A) and Ceiba genus (B), extracted from Ceiba pentandra (L.) Gaertn. in GBIF Secretariat (2021). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/ 39omei accessed via GBIF.org on 31 July 2021.

Fig. 3 .

 3 Fig. 3. Ceiba pentandra tree used for voodoo ceremonies in Cayenne, French Guiana. © Marc-Alexandre Tareau. [Colour online.]

Fig. 4 .

 4 Fig. 4. A Ndjuka maroon healing house ("Obia osu") under a Ceiba pentandra in 2004 close to the Maroni River. © Damien Davy. [Colour online.]

Fig. 5 .

 5 Fig. 5. A preserved silk-cotton tree in Cayenne. © Marc-Alexandre Tareau. [Colour online.]

https://knoema.com/data/agriculture-indicators-production+kapok

Acknowledgements

This work was funded by "Investissement d'Avenir" grants managed by the Agence Nationale de la Recherche (Labex DRIIHM/IRDHEI: ANR-11-LABX-0010 and Labex CEBA: ANR-10-LABX-25-01) and by the Prime80-DiaspoREs projects from the CNRS "Mission pour l'Interdisciplinarité et les Initiatives Transverses".

Originally published in Botany 100: 127-140 (2022) dx.doi.org/10.1139/cjb-2021-0099