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Asteroids (video game)

Asteroids is a space-themed multidirectional shooter arcade video game designed by Lyle Rains and Ed Logg released in November 1979 by Atari, Inc. The player controls a single spaceship in an asteroid field which is periodically traversed by flying saucers. The object of the game is to shoot and destroy the asteroids and saucers, while not colliding with either, or being hit by the saucers' counter-fire. The game becomes harder as the number of asteroids increases.

Asteroids was conceived during a meeting between Logg and Rains, who decided to use hardware developed by Howard Delman previously used for Lunar Lander. Asteroids was based on an unfinished game titled Cosmos; its physics model, control scheme, and gameplay elements were derived from Spacewar!, Computer Space, and Space Invaders and refined through trial and error. The game is rendered on a vector display in a two-dimensional view that wraps around both screen axes.

Asteroids was one of the first major hits of the golden age of arcade games; the game sold 47,840 upright cabinets and 8,725 cocktail cabinets arcade cabinets and proved both popular with players and influential with developers. In the 1980s it was ported to Atari's home systems, and the Atari VCS version sold over three million copies. The game was widely imitated, and it directly influenced Defender, Gravitar, and many other video games.

Gameplay
The objective of Asteroids is to destroy asteroids and saucers. The player controls a triangular ship that can rotate left and right, fire shots straight forward, and thrust forward. Once the ship begins moving in a direction, it will continue in that direction for a time without player intervention unless the player applies thrust in a different direction. The ship eventually comes to a stop when not thrusting. The player can also send the ship into hyperspace, causing it to disappear and reappear in a random location on the screen, at the risk of self-destructing or appearing on top of an asteroid.

Each level starts with a few large asteroids drifting in various directions on the screen. Objects wrap around screen edges – for instance, an asteroid that drifts off the top edge of the screen reappears at the bottom and continues moving in the same direction. As the player shoots asteroids, they break into smaller asteroids that move faster and are more difficult to hit. Smaller asteroids are also worth more points. Two flying saucers appear periodically on the screen; the "big saucer" shoots randomly and poorly, while the "small saucer" fires frequently at the ship. After reaching a score of 40,000, only the small saucer appears. As the player's score increases, the angle range of the shots from the small saucer diminishes until the saucer fires extremely accurately. Once the screen has been cleared of all asteroids and flying saucers, a new set of large asteroids appears, thus starting the next level. The game gets harder as the number of asteroids increases until after the score reaches a range between 40,000 and 60,000. The player starts with 3–5 lives upon game start and gains an extra life per 10,000 points. Play continues to the last ship lost, which ends the game. The machine "turns over" at 99,990 points, which is the maximum high score that can be achieved.

Lurking exploit
In the original game design, saucers were supposed to begin shooting as soon as they appeared, but this was changed. Additionally, saucers can only aim at the player's ship on-screen; they are not capable of aiming across a screen boundary. These behaviors allow a "lurking" strategy, in which the player stays near the edge of the screen opposite the saucer. By keeping just one or two rocks in play, a player can shoot across the boundary and destroy saucers to accumulate points indefinitely with little risk of being destroyed. Arcade operators began to complain about losing revenue due to this exploit. In response, Atari issued a patched EPROM and, due to the impact of this exploit, Atari (and other companies) changed their development and testing policies to try to prevent future games from having such exploits.

Concept
Asteroids was conceived by Lyle Rains and programmed by Ed Logg with collaborations from other Atari staff. Logg was impressed with the Atari Video Computer System (later called the Atari 2600), and he joined Atari's coin-op division to work on Dirt Bike, which was never released due to an unsuccessful field test. Paul Mancuso joined the development team as Asteroids' technician and engineer Howard Delman contributed to the hardware. During a meeting in April 1979, Rains discussed Planet Grab, a multiplayer arcade game later renamed to Cosmos. The unfinished game featured a giant, indestructible asteroid. Logg did play Cosmos and remembered shooting the indestructible asteroid to no effect. So Rains asked Logg: "Well, why don't we have a game where you shoot the rocks and blow them up?" In response, Logg described a similar concept where the player selectively shoots at rocks that break into smaller pieces. Thus combining the two-dimensional approach of Space War with Space Invaders' addictive gameplay of "completion" and "eliminate all threats". Both agreed on the concept.

Hardware
Asteroids was implemented on hardware developed by Delman and is a vector game, in which the graphics are composed of lines drawn on a vector monitor. Rains initially wanted the game done in raster graphics, but Logg, experienced in vector graphics, suggested an XY monitor because the high image quality would permit precise aiming. The hardware is chiefly a MOS 6502 executing the game program, and QuadraScan, a high-resolution vector graphics processor developed by Atari and referred to as an "XY display system" and the "Digital Vector Generator (DVG)".

The original design concepts for QuadraScan came out of Cyan Engineering, Atari's off-campus research lab in Grass Valley, California, in 1978. Cyan gave it to Delman, who finished the design and first used it for Lunar Lander. Logg received Delman's modified board with five buttons, 13 sound effects, and additional RAM, and he used it to develop Asteroids. The size of the board was 4 by 4 inches, and it was "linked up" to a monitor.

Implementation
Logg modeled the player's ship, the five-button control scheme, and the game physics after Spacewar!, which he had played as a student at the University of California, Berkeley, but made several changes to improve playability. The ship was programmed into the hardware and rendered by the monitor, and it was configured to move with thrust and inertia. The hyperspace button was not placed near Logg's right thumb, which he was dissatisfied with, as he had a problem "tak[ing] his hand off the thrust button". Drawings of asteroids in various shapes were incorporated into the game. Logg copied the idea of a high score table with initials from Exidy's Star Fire.

The two saucers were formulated to be different from each other. A steadily decreasing timer shortens intervals between saucer attacks to keep the player from not shooting asteroids and saucers. A "heartbeat" soundtrack quickens as the game progresses. The game does not have a sound chip. Delman created a hardware circuit for 13 sound effects by hand which was wired onto the board.

A prototype of Asteroids was well received by several Atari staff and engineers, who "wander[ed] between labs, passing comment and stopping to play as they went". Logg was often asked when he would be leaving by employees eager to play the prototype, so he created a second prototype for staff to play. Atari tested the game in arcades in Sacramento, California, and also observed players during focus group sessions at Atari. Players used to Spacewar! struggled to maintain grip on the thrust button and requested a joystick; players accustomed to Space Invaders noted they get no break in the game. Logg and other engineers observed proceedings and documented comments in four pages.

Asteroids slows down as the player gains 50–100 lives, because there is no limit to the number of lives displayed. The player can "lose" the game after more than 250 lives are collected.

Ports
Asteroids was released for the Atari VCS (later renamed the Atari 2600) and Atari 8-bit computers in 1981, then the Atari 7800 in 1986. A port for the Atari 5200, identical to the Atari 8-bit computer version, was in development in 1982, but was not published. The Atari 7800 version was a launch title and includes cooperative play; the asteroids have colorful textures and the "heartbeat" sound effect remains intact.

Programmers Brad Stewart and Bob Smith were unable to fit the Atari VCS port into a 4 KB cartridge. It became the first game for the console to use bank switching, a technique that increases ROM size from 4 KB to 8 KB.

Reception
Asteroids was immediately successful upon release. It displaced Space Invaders by popularity in the United States and became Atari's best selling arcade game of all time, with over 70,000 units sold. Atari earned an estimated $150 million in sales from the game, and arcade operators earned a further $500 million from coin drops. Atari had been in the process of manufacturing another vector game, Lunar Lander, but demand for Asteroids was so high "that several hundred Asteroids games were shipped in Lunar Lander cabinets". Asteroids was so popular that some video arcade operators had to install large boxes to hold the number of coins spent by players. It replaced Space Invaders at the top of the US RePlay amusement arcade charts in April 1980, though Space Invaders remained the top game at street locations. Asteroids went on to become the highest-grossing arcade video game of 1980 in the United States, dethroning Space Invaders. It shipped 70,000 arcade units worldwide in 1980, including over 60,000 sold in the United States that year, and grossed about US$700 million worldwide (US$billion adjusted for inflation) by 1980. The game remained at the top of the US RePlay charts through March 1981. The game did not perform as well overseas in Europe and Asia. It sold 30,000 arcade units overseas, for a total of 100,000 arcade units sold worldwide. Atari manufactured 76,312 units from its US and Ireland plants, including 21,394 Asteroids Deluxe units. It was a commercial failure in Japan when it released there in 1980, partly due to its complex controls and partly due to the Japanese market beginning to lose interest in space shoot 'em ups at the time.

Asteroids received positive reviews from video game critics and has been regarded as Logg's magnum opus. Richard A. Edwards reviewed the 1981 Asteroids home cartridge in The Space Gamer No. 46. Edwards commented that "this home cartridge is a virtual duplicate of the ever-popular Atari arcade game. [...] If blasting asteroids is the thing you want to do then this is the game, but at this price I can't wholeheartedly recommend it". Video Games Player magazine reviewed the Atari VCS version, rating the graphics and sound a B, while giving the game an overall B+ rating. Electronic Fun with Computers & Games magazine gave the Atari VCS version an A rating.

William Cassidy, writing for GameSpy's "Classic Gaming", noticed its innovations, including being one of the first video games to track initials and allow players to enter their initials for appearing in the top 10 high scores, and commented that "the vector graphics fit the futuristic outer space theme very well". In 1995, Flux magazine ranked the arcade version 11th on their "Top 100 Video Games". In 1996, Next Generation listed it as number 39 on their "Top 100 Games of All Time", particularly lauding the control dynamics which require "the constant juggling of speed, positioning, and direction". In 1999, Next Generation listed Asteroids as number 29 on their "Top 50 Games of All Time", commenting that "Asteroids was a classic the day it was released, and it has never lost any of its appeal". Asteroids was ranked fourth on Retro Gamer's list of "Top 25 Arcade Games"; the Retro Gamer staff cited its simplicity and the lack of a proper ending as allowances of revisiting the game. In 2012, Asteroids was listed on Time All-Time 100 greatest video games list. Entertainment Weekly named Asteroids one of the top ten games for the Atari 2600 in 2013. It was added to the Museum of Modern Art's collection of video games. In 2021, The Guardian listed Asteroids as the second greatest video game of the 1970s, just below Galaxian (1979). By contrast, in March 1983 the Atari 8-bit port of Asteroids won sixth place in Softline's Dog of the Year awards "for badness in computer games", Atari division, based on reader submissions.

Usage of the names of Saturday Night Live characters "Mr. Bill" and "Sluggo" to refer to the saucers in an Esquire article about the game led to Logg receiving a cease and desist letter from a lawyer with the "Mr. Bill Trademark".

Arcade sequels
Released in 1981, Asteroids Deluxe was the first sequel to Asteroids. Dave Shepperd edited the code and made enhancements to the game without Logg's involvement. The onscreen objects are tinted blue, and hyperspace is replaced by a shield that depletes when used. The asteroids rotate, and new "killer satellite" enemies break into smaller ships that home in on the player's position. The arcade machine's monitor displays vector graphics overlaying a holographic backdrop. The game is more difficult than the original and enables saucers to shoot across the screen boundary, eliminating the lurking strategy for high scores in the original.

Space Duel, released in arcades in 1982, replaces the rocks with colorful geometric shapes and adds cooperative two-player gameplay.

1987's Blasteroids includes power-ups, ship morphing, branching levels, bosses, and the ability to dock ships in multiplayer for added firepower. Blasteroids uses raster graphics instead of vectors.

Re-releases
The game is half of the Atari Lynx pairing Super Asteroids & Missile Command, and included in the 1993 Microsoft Arcade compilation.

Activision published an enhanced version of Asteroids for the PlayStation (1998), Nintendo 64 (1999), Microsoft Windows (1998), Game Boy Color (1999), and Mac (2000). The Atari Flashback series of dedicated video game consoles have included both the 2600 and the arcade versions of Asteroids.

Published by Crave Entertainment on December 14, 1999, Asteroids Hyper 64 made the ship and asteroids 3D, and added new weapons and a multiplayer mode.

A technical demo of Asteroids was developed by iThink for the Atari Jaguar but was never released. Unofficially referred to as Asteroids 2000, it was demonstrated at E-JagFest 2000.

In 2001, Infogrames released Atari Anniversary Edition for the Dreamcast, PlayStation, and Microsoft Windows. Developed by Digital Eclipse, it includes emulated versions of Asteroids and other games. The arcade and Atari 2600 versions of Asteroids were included in Atari Anthology for both Xbox and PlayStation 2.

Released in November 2007, the Xbox Live Arcade port of Asteroids has revamped HD graphics along with an added intense "throttle monkey" mode. The arcade and 2600 versions were made available through Microsoft's Game Room service in 2010. Glu Mobile released an enhanced mobile phone port.

In 2005 Asteroids was released for the Game Boy Advance with Pong and Yars Revenge also being included on the same package.

Asteroids is included on Atari Greatest Hits Volume 1 for the Nintendo DS.

An updated version of the game was announced in 2018 for the Intellivision Amico.

Both the Atari 2600 and Atari 7800 versions of the game were included on Atari Collection 1 and 2 in 2020 for the Evercade.

A remake, Asteroids: Recharged, was released in December 2021 for the Nintendo Switch, PlayStation 4, PlayStation 5, Windows, Xbox One, and Xbox Series X/S, developed by Adamvision Studios and SneakyBox.

Clones
Quality Software's Asteroids in Space (1980) was one of the best selling games for the Apple II and voted one of the most popular software titles of 1978-80 by Softalk magazine. In December 1981, Byte reviewed eight Asteroids clones for home computers. Three clones for the Apple II were reviewed together in the 1982 Creative Computing Software Buyers Guide: The Asteroid Field, Asteron, and Apple-Oids. In the last of these, the asteroids are in the shape of apples. Two independent clones, Asteroid for the Apple II and Fasteroids for TRS-80, were renamed to Planetoids and sold by Adventure International. Others clones include Acornsoft's Meteors, Moons of Jupiter for the VIC-20, MineStorm for the Vectrex, and Quicksilva's Meteor Storm for the ZX Spectrum which uses speech synthesis. A poorly implemented Asteroids clone for the VIC-20, published by Bug-Byte, motivated Jeff Minter to found Llamasoft.

The Intellivision game Meteor! was cancelled to avoid a lawsuit for being too similar to Asteroids and was reworked as Astrosmash. The game borrows elements from Asteroids and Space Invaders.

Proposed film adaptation
In July 2009, Universal Pictures offered Roland Emmerich the option to direct the film adaptation of Asteroids, with Matt Lopez writing the script and Lorenzo di Bonaventura producing the film adaptation. Lopez and di Bonaventura were still attached to write and produce the film adaptation, respectively, but Emmerich passed on directing, while Evan Spiliotopoulos and F. Scott Frazier were hired to rewrite the screenplay.

World records
On February 6, 1982, Leo Daniels of Carolina Beach, North Carolina, set a world record score of 40,101,910 points. On November 13 of the same year, 15-year-old Scott Safran of Cherry Hill, New Jersey, set a new record at 41,336,440 points. In 1998, to congratulate Safran on his accomplishment, the Twin Galaxies Intergalactic Scoreboard searched for him for four years until 2002, when it was discovered that he had died in an accident in 1989. In a ceremony in Philadelphia on April 27, 2002, Walter Day of Twin Galaxies presented an award to the surviving members of Safran's family, commemorating his achievement. On April 5, 2010, John McAllister broke Safran's record with a high score of 41,838,740 in a 58-hour Internet livestream.

title: Asteroids (video game)


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Asparagales

Asparagales (asparagoid lilies) is an order of plants in modern classification systems such as the Angiosperm Phylogeny Group (APG) and the Angiosperm Phylogeny Web. The order takes its name from the type family Asparagaceae and is placed in the monocots amongst the lilioid monocots. The order has only recently been recognized in classification systems. It was first put forward by Huber in 1977 and later taken up in the Dahlgren system of 1985 and then the APG in 1998, 2003 and 2009. Before this, many of its families were assigned to the old order Liliales, a very large order containing almost all monocots with colorful tepals and lacking starch in their endosperm. DNA sequence analysis indicated that many of the taxa previously included in Liliales should actually be redistributed over three orders, Liliales, Asparagales, and Dioscoreales. The boundaries of the Asparagales and of its families have undergone a series of changes in recent years; future research may lead to further changes and ultimately greater stability. In the APG circumscription, Asparagales is the largest order of monocots with 14 families, 1,122 genera, and about 36,000 species.

The order is clearly circumscribed on the basis of molecular phylogenetics, but it is difficult to define morphologically since its members are structurally diverse. Most species of Asparagales are herbaceous perennials, although some are climbers and some are trees or shrubs. The order also contains many geophytes (bulbs, corms, and various kinds of tuber). According to telomere sequence, at least two evolutionary switch-points happened within the order. The basal sequence is formed by TTTAGGG like in the majority of higher plants. Basal motif was changed to vertebrate-like TTAGGG and finally, the most divergent motif CTCGGTTATGGG appears in Allium. One of the defining characteristics (synapomorphies) of the order is the presence of phytomelanin, a black pigment present in the seed coat, creating a dark crust. Phytomelanin is found in most families of the Asparagales (although not in Orchidaceae, thought to be the sister-group of the rest of the order).

The leaves of almost all species form a tight rosette, either at the base of the plant or at the end of the stem, but occasionally along the stem. The flowers are not particularly distinctive, being 'lily type', with six tepals and up to six stamina.

The order is thought to have first diverged from other related monocots some 120–130 million years ago (early in the Cretaceous period), although given the difficulty in classifying the families involved, estimates are likely to be uncertain.

From an economic point of view, the order Asparagales is second in importance within the monocots only to the order Poales (which includes grasses and cereals). Species are used as food and flavourings (e.g. onion, garlic, leek, asparagus, vanilla, saffron), in medicinal or cosmetic applications (Aloe), as cut flowers (e.g. freesia, gladiolus, iris, orchids), and as garden ornamentals (e.g. day lilies, lily of the valley, Agapanthus).

Description

Although most species in the order are herbaceous, some no more than 15 cm high, there are a number of climbers (e.g., some species of Asparagus), as well as several genera forming trees (e.g. Agave, Cordyline, Yucca, Dracaena, Aloe ), which can exceed 10 m in height. Succulent genera occur in several families (e.g. Aloe).

Almost all species have a tight cluster of leaves (a rosette), either at the base of the plant or at the end of a more-or-less woody stem as with Yucca. In some cases, the leaves are produced along the stem. The flowers are in the main not particularly distinctive, being of a general 'lily type', with six tepals, either free or fused from the base and up to six stamina. They are frequently clustered at the end of the plant stem.

The Asparagales are generally distinguished from the Liliales by the lack of markings on the tepals, the presence of septal nectaries in the ovaries, rather than the bases of the tepals or stamen filaments, and the presence of secondary growth. They are generally geophytes, but with linear leaves, and a lack of fine reticular venation.

The seeds characteristically have the external epidermis either obliterated (in most species bearing fleshy fruit), or if present, have a layer of black carbonaceous phytomelanin in species with dry fruits (nuts). The inner part of the seed coat is generally collapsed, in contrast to Liliales whose seeds have a well developed outer epidermis, lack phytomelanin, and usually display a cellular inner layer.

The orders which have been separated from the old Liliales are difficult to characterize. No single morphological character appears to be diagnostic of the order Asparagales.
 * The flowers of Asparagales are of a general type among the lilioid monocots. Compared to Liliales, they usually have plain tepals without markings in the form of dots. If nectaries are present, they are in the septa of the ovaries rather than at the base of the tepals or stamens.
 * Those species which have relatively large dry seeds have a dark, crust-like (crustose) outer layer containing the pigment phytomelan. However, some species with hairy seeds (e.g. Eriospermum, family Asparagaceae s.l.), berries (e.g. Maianthemum, family Asparagaceae s.l.), or highly reduced seeds (e.g. orchids) lack this dark pigment in their seed coats. Phytomelan is not unique to Asparagales (i.e. it is not a synapomorphy) but it is common within the order and rare outside it. The inner portion of the seed coat is usually completely collapsed. In contrast, the morphologically similar seeds of Liliales have no phytomelan, and usually retain a cellular structure in the inner portion of the seed coat.
 * Most monocots are unable to thicken their stems once they have formed, since they lack the cylindrical meristem present in other angiosperm groups. Asparagales have a method of secondary thickening which is otherwise only found in Dioscorea (in the monocot order Disoscoreales). In a process called 'anomalous secondary growth', they are able to create new vascular bundles around which thickening growth occurs. Agave, Yucca, Aloe, Dracaena, Nolina and Cordyline can become massive trees, albeit not of the height of the tallest dicots, and with less branching. Other genera in the order, such as Lomandra and Aphyllanthes, have the same type of secondary growth but confined to their underground stems.
 * Microsporogenesis (part of pollen formation) distinguishes some members of Asparagales from Liliales. Microsporogenesis involves a cell dividing twice (meiotically) to form four daughter cells. There are two kinds of microsporogenesis: successive and simultaneous (although intermediates exist). In successive microsporogenesis, walls are laid down separating the daughter cells after each division. In simultaneous microsporogenesis, there is no wall formation until all four cell nuclei are present. Liliales all have successive microsporogenesis, which is thought to be the primitive condition in monocots. It seems that when the Asparagales first diverged they developed simultaneous microsporogenesis, which the 'lower' Asparagales families retain. However, the 'core' Asparagales (see Phylogenetics ) have reverted to successive microsporogenesis.
 * The Asparagales appear to be unified by a mutation affecting their telomeres (a region of repetitive DNA at the end of a chromosome). The typical 'Arabidopsis-type' sequence of bases has been fully or partially replaced by other sequences, with the 'human-type' predominating.
 * Other apomorphic characters of the order according to Stevens are: the presence of chelidonic acid, anthers longer than wide, tapetal cells bi- to tetra-nuclear, tegmen not persistent, endosperm helobial, and loss of mitochondrial gene sdh3.

Taxonomy
As circumscribed within the Angiosperm Phylogeny Group system Asparagales is the largest order within the monocotyledons, with 14 families, 1,122 genera and about 25,000–42,000 species, thus accounting for about 50% of all monocots and 10–15% of the flowering plants (angiosperms). The attribution of botanical authority for the name Asparagales belongs to Johann Heinrich Friedrich Link (1767–1851) who coined the word 'Asparaginae' in 1829 for a higher order taxon that included Asparagus although Adanson and Jussieau had also done so earlier (see History). Earlier circumscriptions of Asparagales attributed the name to Bromhead (1838), who had been the first to use the term 'Asparagales'.

Pre-Darwinian
The type genus, Asparagus, from which the name of the order is derived, was described by Carl Linnaeus in 1753, with ten species. He placed Asparagus within the Hexandria Monogynia (six stamens, one carpel) in his sexual classification in the Species Plantarum. The majority of taxa now considered to constitute Asparagales have historically been placed within the very large and diverse family, Liliaceae. The family Liliaceae was first described by Michel Adanson in 1763, and in his taxonomic scheme he created eight sections within it, including the Asparagi with Asparagus and three other genera. The system of organising genera into families is generally credited to Antoine Laurent de Jussieu who formally described both the Liliaceae and the type family of Asparagales, the Asparagaceae, as Lilia and Asparagi, respectively, in 1789. Jussieu established the hierarchical system of taxonomy (phylogeny), placing Asparagus and related genera within a division of Monocotyledons, a class (III) of Stamina Perigynia and 'order' Asparagi, divided into three subfamilies. The use of the term Ordo (order) at that time was closer to what we now understand as Family, rather than Order. In creating his scheme he used a modified form of Linnaeus' sexual classification but using the respective topography of stamens to carpels rather than just their numbers. While De Jussieu's Stamina Perigynia also included a number of 'orders' that would eventually form families within the Asparagales such as the Asphodeli (Asphodelaceae), Narcissi (Amaryllidaceae) and Irides (Iridaceae), the remainder are now allocated to other orders. Jussieu's Asparagi soon came to be referred to as Asparagacées in the French literature (Latin: Asparagaceae). Meanwhile, the 'Narcissi' had been renamed as the 'Amaryllidées' (Amaryllideae) in 1805, by Jean Henri Jaume Saint-Hilaire, using Amaryllis as the type species rather than Narcissus, and thus has the authority attribution for Amaryllidaceae. In 1810, Brown proposed that a subgroup of Liliaceae be distinguished on the basis of the position of the ovaries and be referred to as Amaryllideae and in 1813 de Candolle described Liliacées Juss. and Amaryllidées Brown as two quite separate families.

The literature on the organisation of genera into families and higher ranks became available in the English language with Samuel Frederick Gray's A natural arrangement of British plants (1821). Gray used a combination of Linnaeus' sexual classification and Jussieu's natural classification to group together a number of families having in common six equal stamens, a single style and a perianth that was simple and petaloid, but did not use formal names for these higher ranks. Within the grouping he separated families by the characteristics of their fruit and seed. He treated groups of genera with these characteristics as separate families, such as Amaryllideae, Liliaceae, Asphodeleae and Asparageae.

The circumscription of Asparagales has been a source of difficulty for many botanists from the time of John Lindley (1846), the other important British taxonomist of the early nineteenth century. In his first taxonomic work, An Introduction to the Natural System of Botany (1830) he partly followed Jussieu by describing a subclass he called Endogenae, or Monocotyledonous Plants (preserving de Candolle's Endogenæ phanerogamæ) divided into two tribes, the Petaloidea and Glumaceae. He divided the former, often referred to as petaloid monocots, into 32 orders, including the Liliaceae (defined narrowly), but also most of the families considered to make up the Asparagales today, including the Amaryllideae.

By 1846, in his final scheme Lindley had greatly expanded and refined the treatment of the monocots, introducing both an intermediate ranking (Alliances) and tribes within orders (i.e. families). Lindley placed the Liliaceae within the Liliales, but saw it as a paraphyletic ("catch-all") family, being all Liliales not included in the other orders, but hoped that the future would reveal some characteristic that would group them better. The order Liliales was very large and included almost all monocotyledons with colourful tepals and without starch in their endosperm (the lilioid monocots). The Liliales was difficult to divide into families because morphological characters were not present in patterns that clearly demarcated groups. This kept the Liliaceae separate from the Amaryllidaceae (Narcissales). Of these, Liliaceae was divided into eleven tribes (with 133 genera) and Amaryllidaceae into four tribes (with 68 genera), yet both contained many genera that would eventually segregate to each other's contemporary orders (Liliales and Asparagales respectively). The Liliaceae would be reduced to a small 'core' represented by the tribe Tulipae, while large groups such Scilleae and Asparagae would become part of Asparagales either as part of the Amaryllidaceae or as separate families. While of the Amaryllidaceae, the Agaveae would be part of Asparagaceae but the Alstroemeriae would become a family within the Liliales.

The number of known genera (and species) continued to grow and by the time of the next major British classification, that of the Bentham & Hooker system in 1883 (published in Latin) several of Lindley's other families had been absorbed into the Liliaceae. They used the term 'series' to indicate suprafamilial rank, with seven series of monocotyledons (including Glumaceae), but did not use Lindley's terms for these. However, they did place the Liliaceous and Amaryllidaceous genera into separate series. The Liliaceae were placed in series Coronariae, while the Amaryllideae were placed in series Epigynae. The Liliaceae now consisted of twenty tribes (including Tulipeae, Scilleae and Asparageae), and the Amaryllideae of five (including Agaveae and Alstroemerieae). An important addition to the treatment of the Liliaceae was the recognition of the Allieae as a distinct tribe that would eventually find its way to the Asparagales as the subfamily Allioideae of the Amaryllidaceae.

Post-Darwinian
The appearance of Charles Darwin's Origin of Species in 1859 changed the way that taxonomists considered plant classification, incorporating evolutionary information into their schemata. The Darwinian approach led to the concept of phylogeny (tree-like structure) in assembling classification systems, starting with Eichler. Eichler, having established a hierarchical system in which the flowering plants (angiosperms) were divided into monocotyledons and dicotyledons, further divided into former into seven orders. Within the Liliiflorae were seven families, including Liliaceae and Amaryllidaceae. Liliaceae included Allium and Ornithogalum (modern Allioideae) and Asparagus.

Engler, in his system developed Eichler's ideas into a much more elaborate scheme which he treated in a number of works including Die Natürlichen Pflanzenfamilien (Engler and Prantl 1888) and Syllabus der Pflanzenfamilien (1892–1924). In his treatment of Liliiflorae the Liliineae were a suborder which included both families Liliaceae and Amaryllidaceae. The Liliaceae had eight subfamilies and the Amaryllidaceae four. In this rearrangement of Liliaceae, with fewer subdivisions, the core Liliales were represented as subfamily Lilioideae (with Tulipae and Scilleae as tribes), the Asparagae were represented as Asparagoideae and the Allioideae was preserved, representing the alliaceous genera. Allieae, Agapantheae and Gilliesieae were the three tribes within this subfamily. In the Amaryllidaceae, there was little change from the Bentham & Hooker. A similar approach was adopted by Wettstein.

Twentieth century
In the twentieth century the Wettstein system (1901–1935) placed many of the taxa in an order called 'Liliiflorae'. Next Johannes Paulus Lotsy (1911) proposed dividing the Liliiflorae into a number of smaller families including Asparagaceae. Then Herbert Huber (1969, 1977), following Lotsy's example, proposed that the Liliiflorae be split into four groups including the 'Asparagoid' Liliiflorae. The widely used Cronquist system (1968–1988) used the very broadly defined order Liliales.

These various proposals to separate small groups of genera into more homogeneous families made little impact till that of Dahlgren (1985) incorporating new information including synapomorphy. Dahlgren developed Huber's ideas further and popularised them, with a major deconstruction of existing families into smaller units. They created a new order, calling it Asparagales. This was one of five orders within the superorder Liliiflorae. Where Cronquist saw one family, Dahlgren saw forty distributed over three orders (predominantly Liliales and Asparagales). Over the 1980s, in the context of a more general review of the classification of angiosperms, the Liliaceae were subjected to more intense scrutiny. By the end of that decade, the Royal Botanic Gardens at Kew, the British Museum of Natural History and the Edinburgh Botanical Gardens formed a committee to examine the possibility of separating the family at least for the organization of their herbaria. That committee finally recommended that 24 new families be created in the place of the original broad Liliaceae, largely by elevating subfamilies to the rank of separate families.

Phylogenetics
The order Asparagales as currently circumscribed has only recently been recognized in classification systems, through the advent of phylogenetics. The 1990s saw considerable progress in plant phylogeny and phylogenetic theory, enabling a phylogenetic tree to be constructed for all of the flowering plants. The establishment of major new clades necessitated a departure from the older but widely used classifications such as Cronquist and Thorne based largely on morphology rather than genetic data. This complicated the discussion about plant evolution and necessitated a major restructuring. rbcL gene sequencing and cladistic analysis of monocots had redefined the Liliales in 1995. from four morphological orders sensu Dahlgren. The largest clade representing the Liliaceae, all previously included in Liliales, but including both the Calochortaceae and Liliaceae sensu Tamura. This redefined family, that became referred to as core Liliales, but corresponded to the emerging circumscription of the Angiosperm Phylogeny Group (1998).

Phylogeny and APG system
The 2009 revision of the Angiosperm Phylogeny Group system, APG III, places the order in the clade monocots.

From the Dahlgren system of 1985 onwards, studies based mainly on morphology had identified the Asparagales as a distinct group, but had also included groups now located in Liliales, Pandanales and Zingiberales. Research in the 21st century has supported the monophyly of Asparagales, based on morphology, 18S rDNA, and other DNA sequences, although some phylogenetic reconstructions based on molecular data have suggested that Asparagales may be paraphyletic, with Orchidaceae separated from the rest. Within the monocots, Asparagales is the sister group of the commelinid clade.

This cladogram shows the placement of Asparagales within the orders of Lilianae sensu Chase & Reveal (monocots) based on molecular phylogenetic evidence. The lilioid monocot orders are bracketed, namely Petrosaviales, Dioscoreales, Pandanales, Liliales and Asparagales. These constitute a paraphyletic assemblage, that is groups with a common ancestor that do not include all direct descendants (in this case commelinids as the sister group to Asparagales); to form a clade, all the groups joined by thick lines would need to be included. While Acorales and Alismatales have been collectively referred to as "alismatid monocots" (basal or early branching monocots), the remaining clades (lilioid and commelinid monocots) have been referred to as the "core monocots". The relationship between the orders (with the exception of the two sister orders) is pectinate, that is diverging in succession from the line that leads to the commelinids. Numbers indicate crown group (most recent common ancestor of the sampled species of the clade of interest) divergence times in mya (million years ago).

Subdivision
A phylogenetic tree for the Asparagales, generally to family level, but including groups which were recently and widely treated as families but which are now reduced to subfamily rank, is shown below.

The tree shown above can be divided into a basal paraphyletic group, the 'lower Asparagales (asparagoids)', from Orchidaceae to Asphodelaceae, and a well-supported monophyletic group of 'core Asparagales' (higher asparagoids), comprising the two largest families, Amaryllidaceae sensu lato and Asparagaceae sensu lato.

Two differences between these two groups (although with exceptions) are: the mode of microsporogenesis and the position of the ovary. The 'lower Asparagales' typically have simultaneous microsporogenesis (i.e. cell walls develop only after both meiotic divisions), which appears to be an apomorphy within the monocots, whereas the 'core Asparagales' have reverted to successive microsporogenesis (i.e. cell walls develop after each division). The 'lower Asparagales' typically have an inferior ovary, whereas the 'core Asparagales' have reverted to a superior ovary. A 2002 morphological study by Rudall treated possessing an inferior ovary as a synapomorphy of the Asparagales, stating that reversions to a superior ovary in the 'core Asparagales' could be associated with the presence of nectaries below the ovaries. However, Stevens notes that superior ovaries are distributed among the 'lower Asparagales' in such a way that it is not clear where to place the evolution of different ovary morphologies. The position of the ovary seems a much more flexible character (here and in other angiosperms) than previously thought.

Changes to family structure in APG III
The APG III system when it was published in 2009, greatly expanded the families Xanthorrhoeaceae, Amaryllidaceae, and Asparagaceae. Thirteen of the families of the earlier APG II system were thereby reduced to subfamilies within these three families. The expanded Xanthorrhoeaceae is now called "Asphodelaceae". The APG II families (left) and their equivalent APG III subfamilies (right) are as follows:

Orchid clade
Orchidaceae is possibly the largest family of all angiosperms (only Asteraceae might - or might not - be more speciose) and hence by far the largest in the order. The Dahlgren system recognized three families of orchids, but DNA sequence analysis later showed that these families are polyphyletic and so should be combined. Several studies suggest (with high bootstrap support) that Orchidaceae is the sister of the rest of the Asparagales. Other studies have placed the orchids differently in the phylogenetic tree, generally among the Boryaceae-Hypoxidaceae clade. The position of Orchidaceae shown above seems the best current hypothesis, but cannot be taken as confirmed.

Orchids have simultaneous microsporogenesis and inferior ovaries, two characters that are typical of the 'lower Asparagales'. However, their nectaries are rarely in the septa of the ovaries, and most orchids have dust-like seeds, atypical of the rest of the order. (Some members of Vanilloideae and Cypripedioideae have crustose seeds, probably associated with dispersal by birds and mammals that are attracted by fermenting fleshy fruit releasing fragrant compounds, e.g. vanilla.)

In terms of the number of species, Orchidaceae diversification is remarkable, with recent estimations suggesting that despite the old origin of the family dating back to the late cretaceous, modern orchid diversity originated mostly during the last 5 million years. However, although the other Asparagales may be less rich in species, they are more variable morphologically, including tree-like forms.

Boryaceae to Hypoxidaceae
The four families excluding Boryaceae form a well-supported clade in studies based on DNA sequence analysis. All four contain relatively few species, and it has been suggested that they be combined into one family under the name Hypoxidaceae sensu lato. The relationship between Boryaceae (which includes only two genera, Borya and Alania), and other Asparagales has remained unclear for a long time. The Boryaceae are mycorrhizal, but not in the same way as orchids. Morphological studies have suggested a close relationship between Boryaceae and Blandfordiaceae. There is relatively low support for the position of Boryaceae in the tree shown above.

Ixioliriaceae to Xeronemataceae
The relationship shown between Ixioliriaceae and Tecophilaeaceae is still unclear. Some studies have supported a clade of these two families, others have not. The position of Doryanthaceae has also varied, with support for the position shown above, but also support for other positions.

The clade from Iridaceae upwards appears to have stronger support. All have some genetic characteristics in common, having lost Arabidopsis-type telomeres. Iridaceae is distinctive among the Asparagales in the unique structure of the inflorescence (a rhipidium), the combination of an inferior ovary and three stamens, and the common occurrence of unifacial leaves whereas bifacial leaves are the norm in other Asparagales.

Members of the clade from Iridaceae upwards have infra-locular septal nectaries, which Rudall interpreted as a driver towards secondarily superior ovaries.

Asphodelaceae + 'core Asparagales'
The next node in the tree (Xanthorrhoeaceae sensu lato + the 'core Asparagales') has strong support. 'Anomalous' secondary thickening occurs among this clade, e.g. in Xanthorrhoea (family Asphodelaceae) and Dracaena (family Asparagaceae sensu lato), with species reaching tree-like proportions.

The 'core Asparagales', comprising Amaryllidaceae sensu lato and Asparagaceae sensu lato, are a strongly supported clade, as are clades for each of the families. Relationships within these broadly defined families appear less clear, particularly within the Asparagaceae sensu lato. Stevens notes that most of its subfamilies are difficult to recognize, and that significantly different divisions have been used in the past, so that the use of a broadly defined family to refer to the entire clade is justified. Thus the relationships among subfamilies shown above, based on APWeb, is somewhat uncertain.

Evolution
Several studies have attempted to date the evolution of the Asparagales, based on phylogenetic evidence. Earlier studies generally give younger dates than more recent studies, which have been preferred in the table below.

A 2009 study suggests that the Asparagales have the highest diversification rate in the monocots, about the same as the order Poales, although in both orders the rate is little over half that of the eudicot order Lamiales, the clade with the highest rate.

Comparison of family structures
The taxonomic diversity of the monocotyledons is described in detail by Kubitzki. Up-to-date information on the Asparagales can be found on the Angiosperm Phylogeny Website.

The APG III system's family circumscriptions are being used as the basis of the Kew-hosted World Checklist of Selected Plant Families. With this circumscription, the order consists of 14 families (Dahlgren had 31) with approximately 1120 genera and 26000 species.

Order Asparagales Link
 * Family Amaryllidaceae J.St.-Hil. (including Agapanthaceae F.Voigt, Alliaceae Borkh. )
 * Family Asparagaceae Juss. (including Agavaceae Dumort. [which includes Anemarrhenaceae, Anthericaceae, Behniaceae and Herreriaceae], Aphyllanthaceae Burnett , Hesperocallidaceae Traub , Hyacinthaceae Batsch ex Borkh. , Laxmanniaceae Bubani , Ruscaceae M.Roem. [which includes Convallariaceae] and Themidaceae Salisb. )
 * Family Asteliaceae Dumort.
 * Family Blandfordiaceae R.Dahlgren & Clifford
 * Family Boryaceae M.W. Chase, Rudall & Conran
 * Family Doryanthaceae R.Dahlgren & Clifford
 * Family Hypoxidaceae R.Br.
 * Family Iridaceae Juss.
 * Family Ixioliriaceae Nakai
 * Family Lanariaceae R.Dahlgren & A.E.van Wyk
 * Family Orchidaceae Juss.
 * Family Tecophilaeaceae Leyb.
 * Family Xanthorrhoeaceae Dumort. (including Asphodelaceae Juss. and Hemerocallidaceae R.Br. ), now Asphodelaceae Juss.
 * Family Xeronemataceae M.W.Chase, Rudall & M.F.Fay

The earlier 2003 version, APG II, allowed 'bracketed' families, i.e. families which could either be segregated from more comprehensive families or could be included in them. These are the families given under "including" in the list above. APG III does not allow bracketed families, requiring the use of the more comprehensive family; otherwise the circumscription of the Asparagales is unchanged. A separate paper accompanying the publication of the 2009 APG III system provided subfamilies to accommodate the families which were discontinued. The first APG system of 1998 contained some extra families, included in square brackets in the list above.

Two older systems which use the order Asparagales are the Dahlgren system and the Kubitzki system. The families included in the circumscriptions of the order in these two systems are shown in the first and second columns of the table below. The equivalent family in the modern APG III system (see below) is shown in the third column. Note that although these systems may use the same name for a family, the genera which it includes may be different, so the equivalence between systems is only approximate in some cases.

Uses
The Asparagales include many important crop plants and ornamental plants. Crops include Allium, Asparagus and Vanilla, while ornamentals include irises, hyacinths and orchids.

Books

 * contents

Chapters

 * in
 * in
 * in
 * in

Historical sources

 * digital edition by the University and State Library Düsseldorf
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * digital edition by the University and State Library Düsseldorf
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * digital edition by the University and State Library Düsseldorf
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * digital edition by the University and State Library Düsseldorf
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935
 * 1st ed. 1901–1908; 2nd ed. 1910–1911; 3rd ed. 1923–1924; 4th ed. 1933–1935

Websites

 * : Families included in the checklist
 * : Families included in the checklist
 * : Families included in the checklist
 * : Families included in the checklist

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Asparagales


text:
Alismatales

The Alismatales (alismatids) are an order of flowering plants including about 4,500 species. Plants assigned to this order are mostly tropical or aquatic. Some grow in fresh water, some in marine habitats. Perhaps the most important food crop in the order is the taro plant, Colocasia esculenta.

Description
The Alismatales comprise herbaceous flowering plants of often aquatic and marshy habitats, and the only monocots known to have green embryos other than the Amaryllidaceae. They also include the only marine angiosperms growing completely submerged, the seagrasses. The flowers are usually arranged in inflorescences, and the mature seeds lack endosperm.

Both marine and freshwater forms include those with staminate flowers that detach from the parent plant and float to the surface. There they can pollinate carpellate flowers floating on the surface via long pedicels. In others, pollination occurs underwater, where pollen may form elongated strands, increasing chance of success. Most aquatic species have a totally submerged juvenile phase, and flowers are either floating or emerge above the water's surface. Vegetation may be totally submersed, have floating leaves, or protrude from the water. Collectively, they are commonly known as "water plantain".

Taxonomy
The Alismatales contain about 165 genera in 13 families, with a cosmopolitan distribution. Phylogenetically, they are basal monocots, diverging early in evolution relative to the lilioid and commelinid monocot lineages. Together with the Acorales, the Alismatales are referred to informally as the alismatid monocots.

Early systems
The Cronquist system (1981) places the Alismatales in subclass Alismatidae, class Liliopsida [= monocotyledons] and includes only three families as shown: Cronquist's subclass Alismatidae conformed fairly closely to the order Alismatales as defined by APG, minus the Araceae.
 * Alismataceae
 * Butomaceae
 * Limnocharitaceae

The Dahlgren system places the Alismatales in the superorder Alismatanae in the subclass Liliidae [= monocotyledons] in the class Magnoliopsida [= angiosperms] with the following families included:
 * Alismataceae
 * Aponogetonaceae
 * Butomaceae
 * Hydrocharitaceae
 * Limnocharitaceae

In Tahktajan's classification (1997), the order Alismatales contains only the Alismataceae and Limnocharitaceae, making it equivalent to the Alismataceae as revised in APG-III. Other families included in the Alismatates as currently defined are here distributed among 10 additional orders, all of which are assigned, with the following exception, to the Subclass Alismatidae. Araceae in Tahktajan 1997 is assigned to the Arales and placed in the Subclass Aridae; Tofieldiaceae to the Melanthiales and placed in the Liliidae.

Angiosperm Phylogeny Group
The Angiosperm Phylogeny Group system (APG) of 1998 and APG II (2003) assigned the Alismatales to the monocots, which may be thought of as an unranked clade containing the families listed below. The biggest departure from earlier systems (see below) is the inclusion of family Araceae. By its inclusion, the order has grown enormously in number of species. The family Araceae alone accounts for about a hundred genera, totaling over two thousand species. The rest of the families together contain only about five hundred species, many of which are in very small families.

The APG III system (2009) differs only in that the Limnocharitaceae are combined with the Alismataceae; it was also suggested that the genus Maundia (of the Juncaginaceae) could be separated into a monogeneric family, the Maundiaceae, but the authors noted that more study was necessary before the Maundiaceae could be recognized.

 * order Alismatales sensu APG III
 * family Alismataceae (including Limnocharitaceae)
 * family Aponogetonaceae
 * family Araceae
 * family Butomaceae
 * family Cymodoceaceae
 * family Hydrocharitaceae
 * family Juncaginaceae
 * family Posidoniaceae
 * family Potamogetonaceae
 * family Ruppiaceae
 * family Scheuchzeriaceae
 * family Tofieldiaceae
 * family Zosteraceae

In APG IV (2016), it was decided that evidence was sufficient to elevate Maundia to family level as the monogeneric Maundiaceae. The authors considered including a number of the smaller orders within the Juncaginaceae, but an online survey of botanists and other users found little support for this "lumping" approach. Consequently, the family structure for APG IV is:

 * family Alismataceae (including Limnocharitaceae)
 * family Aponogetonaceae
 * family Araceae
 * family Butomaceae
 * family Cymodoceaceae
 * family Hydrocharitaceae
 * family Juncaginaceae
 * family Maundiaceae
 * family Posidoniaceae
 * family Potamogetonaceae
 * family Ruppiaceae
 * family Scheuchzeriaceae
 * family Tofieldiaceae
 * family Zosteraceae

Phylogeny
Cladogram showing the orders of monocots (Lilianae sensu Chase & Reveal) based on molecular phylogenetic evidence:

title: Alismatales


text:
Apiales

The Apiales are an order of flowering plants. The families are those recognized in the APG III system. This is typical of the newer classifications, though there is some slight variation and in particular, the Torriceliaceae may also be divided.

Under this definition, well-known members include carrots, celery, parsley, and Hedera helix (English ivy).

The order Apiales is placed within the asterid group of eudicots as circumscribed by the APG III system. Within the asterids, Apiales belongs to an unranked group called the campanulids, and within the campanulids, it belongs to a clade known in phylogenetic nomenclature as Apiidae. In 2010, a subclade of Apiidae named Dipsapiidae was defined to consist of the three orders: Apiales, Paracryphiales, and Dipsacales.

Taxonomy
Under the Cronquist system, only the Apiaceae and Araliaceae were included here, and the restricted order was placed among the rosids rather than the asterids. The Pittosporaceae were placed within the Rosales, and many of the other forms within the family Cornaceae. Pennantia was in the family Icacinaceae. In the classification system of Dahlgren the families Apiaceae and Araliaceae were placed in the order Ariales, in the superorder Araliiflorae (also called Aralianae).

The present understanding of the Apiales is fairly recent and is based upon comparison of DNA sequences by phylogenetic methods. The circumscriptions of some of the families have changed. In 2009, one of the subfamilies of Araliaceae was shown to be polyphyletic.

Gynoecia
The largest and obviously closely related families of Apiales are Araliaceae, Myodocarpaceae and Apiaceae, which resemble each other in the structure of their gynoecia. In this respect however, the Pittosporaceae is notably distinct from them.

Typical syncarpous gynoecia exhibit four vertical zones, determined by the extent of fusion of the carpels. In most plants, the synascidiate (i.e. "united bottle-shaped") and symplicate zones are fertile and bear the ovules. Each of the first three families possess mainly bi- or multilocular ovaries in a gynoecium with a long synascidiate, but very short symplicate zone, where the ovules are inserted at their transition, the so-called cross-zone (or "Querzone").

In gynoecia of the Pittosporaceae, the symplicate is much longer than the synascidiate zone, and the ovules are arranged along the first. Members of the latter family consequently have unilocular ovaries with a single cavity between adjacent carpels.

title: Apiales


text:
Asterales

Asterales is an order of dicotyledonous flowering plants that includes the large family Asteraceae (or Compositae) known for composite flowers made of florets, and ten families related to the Asteraceae. While asterids in general are characterized by fused petals, composite flowers consisting of many florets create the false appearance of separate petals (as found in the rosids).

The order is cosmopolitan (plants found throughout most of the world including desert and frigid zones), and includes mostly herbaceous species, although a small number of trees (such as the Lobelia deckenii, the giant lobelia, and Dendrosenecio, giant groundsels) and shrubs are also present.

Asterales are organisms that seem to have evolved from one common ancestor. Asterales share characteristics on morphological and biochemical levels. Synapomorphies (a character that is shared by two or more groups through evolutionary development) include the presence in the plants of oligosaccharide inulin, a nutrient storage molecule used instead of starch; and unique stamen morphology. The stamens are usually found around the style, either aggregated densely or fused into a tube, probably an adaptation in association with the plunger (brush; or secondary) pollination that is common among the families of the order, wherein pollen is collected and stored on the length of the pistil.

Taxonomy
The name and order Asterales is botanically venerable, dating back to at least 1926 in the Hutchinson system of plant taxonomy when it contained only five families, of which only two are retained in the APG III classification. Under the Cronquist system of taxonomic classification of flowering plants, Asteraceae was the only family in the group, but newer systems (such as APG II and APG III) have expanded it to 11. In the classification system of Rolf Dahlgren the Asterales were in the superorder Asteriflorae (also called Asteranae).

The order Asterales currently includes 11 families, the largest of which are the Asteraceae, with about 25,000 species, and the Campanulaceae (bellflowers), with about 2,000 species. The remaining families count together for less than 1500 species. The two large families are cosmopolitan, with many of their species found in the Northern Hemisphere, and the smaller families are usually confined to Australia and the adjacent areas, or sometimes South America.

Only the Asteraceae have composite flower heads; the other families do not, but share other characteristics such as storage of inulin that define the 11 families as more closely related to each other than to other plant families or orders such as the rosids.

The phylogenetic tree according to APG III for the Campanulid clade is as below.

Phylogeny
Although most extant species of Asteraceae are herbaceous, the examination of the basal members in the family suggests that the common ancestor of the family was an arborescent plant, a tree or shrub, perhaps adapted to dry conditions, radiating from South America. Less can be said about the Asterales themselves with certainty, although since several families in Asterales contain trees, the ancestral member is most likely to have been a tree or shrub.

Because all clades are represented in the Southern Hemisphere but many not in the Northern Hemisphere, it is natural to conjecture that there is a common southern origin to them. Asterales are angiosperms, flowering plants that appeared about 140 million years ago. The Asterales order probably originated in the Cretaceous (145 – 66 Mya) on the supercontinent Gondwana which broke up from 184 – 80 Mya, forming the area that is now Australia, South America, Africa, India and Antarctica.

Asterales contain about 14% of eudicot diversity. From an analysis of relationships and diversities within the Asterales and with their superorders, estimates of the age of the beginning of the Asterales have been made, which range from 116 Mya to 82Mya. However few fossils have been found, of the Menyanthaceae-Asteraceae clade in the Oligocene, about 29 Mya.

Fossil evidence of the Asterales is rare and belongs to rather recent epochs, so the precise estimation of the order's age is quite difficult. An Oligocene (34 – 23 Mya) pollen is known for Asteraceae and Goodeniaceae, and seeds from Oligocene and Miocene (23 – 5.3 Mya) are known for Menyanthaceae and Campanulaceae respectively.

Biogeography
The core Asterales are Stylidiaceae (six genera), APA clade (Alseuosmiaceae, Phellinaceae and Argophyllaceae, together seven genera), MGCA clade (Menyanthaceae, Goodeniaceae, Calyceraceae, in total twenty genera), and Asteraceae (about sixteen hundred genera). Other Asterales are Rousseaceae (four genera), Campanulaceae (eighty-four genera) and Pentaphragmataceae (one genus).

All Asterales families are represented in the Southern Hemisphere; however, Asteraceae and Campanulaceae are cosmopolitan and Menyanthaceae nearly so.

Uses
The Asterales, by dint of being a super-set of the family Asteraceae, include some species grown for food, including the sunflower (Helianthus annuus), lettuce (Lactuca sativa) and chicory (Cichorium). Many are also used as spices and traditional medicines.

Asterales are common plants and have many known uses. For example, pyrethrum (derived from Old World members of the genus Chrysanthemum) is a natural insecticide with minimal environmental impact. Wormwood, derived from a genus that includes the sagebrush, is used as a source of flavoring for absinthe, a bitter classical liquor of European origin.

title: Asterales