Kingdom Plantae

Body type: multicellular with cell walls made of cellulose 

Prokaryotic / eukaryotic: eukaryotic 

Food consumption: photosynthesis (absorbs light) 

Reproduction: both sexual and asexual 

Environments: land and water 

Hetero / Chemo / Autotrophic: Autotrophic 

Characteristics: Plants have organs and organ systems. The leaves collect and absorb sunlight to convert to glucose. The leaves have a waxy coat on them to shield against water. The root system, which branches out, provides support and absorbs water. The stem provides support and the petal / flower / bud is the reproductive organ of the plant. 

DIVISION BRYOPHYTA (MOSSES & LIVERWORTS)

Mosses have minute "leaves" and stalks bearing a terminal capsule (sporangium) containing spores; moss sex organs (male antheridia and female archegonia) are typically produced on the leafy gametophytes of separate male and female plants; liverworts have a dorsi-ventrally flattened thallus with tiny palmlike stalks bearing male and female sex organs; the gametophyte thallus of some species also bears small, cuplike structures called gemmae cups; the cups contain lens-shaped buds called gemmae which can grow asexually into new thallus plants; there are aquatic and terrestrial forms of mosses and liverworts, some of which have a flattened, thallus that superficially resembles certain forms of green algae; these fascinating little nonvascular embryophytes are often subdivided into two separate divisions.

CLASSES

TAKAKIA

Takakia is a genus of only two species of moss known from western North America and central and eastern Asia. The genus is placed as a separate family, order and class among the mosses. It has had a history of uncertain placement, but the discovery of sporophytes clearly of the moss-

type firmly supports placement with the mosses.DescriptionTakakia is not only unusual among mosses, but among all living plants. The plant's Japanese name (nanjamonja-goke) "impossible moss" reflects this.[5] It was believed to have the lowest known chromosome count (n=4) per cell of any land plant.[6], but some plants of the small Australian daisy Brachyscome dichromosomatica are now known to have a count of n=2.[7]

From a distance, Takakia looks like a typical layer of moss or green algae on the rock where it grows. On closer inspection, tiny shoots of Takakia grow from a turf of slender, creeping rhizomes. The green shoots which grow up from the turf are seldom taller than 1 cm, and bear an irregular arrangement of short, finger-like leaves (1 mm long). These leaves are deeply divided into two or more filaments, a characteristic not found in any other moss. [8] Both the green shoots and their leaves are very brittle.Unlike in other bryophytes, the egg-producing archegonia and sperm-producing antheridia are not surrounded by perichaetial leaves or other protective tissues. Instead, the gametangia are naked in the angle formed between the stem and the vegetative leaves. The sporophyte develops a long stalk ending in an elongatedspore capsule. The capsule contains a central columella ("little column") over and around which the spores are produced. When the sporophyte is mature, the capsule ruptures along a single, spiral slit to release the spores.

SPHAGNOPSIDA

The Sphagnopsida includes a single subclass Sphagnidae, with two orders. The order Sphagnales contains four living genera: Sphagnum, with all but three of the species, and Ambuchanania, Eosphagnum, and Flatbergium, each with a single species. The Protosphagnales contains a single fossil species.

ANDREAEACEAE

Andreaeaceae is a family of mosses which includes two genera, Andreaea, containing about 100 species, and the genus Acroschisma. The Andreaeaceae prefer rocky habitats ranging from tropical to arctic climates, on which they form tufted colonies, typically with reddish to blackish shoots. The capsules lack the peristome mechanism and dehisce longitudinally to release the spores, resulting in a paper-lantern appearance.

ANDREAEOBRYUM

Andreaeobryum is a genus of moss with a single species Andreaeobryum macrosporum, endemic to Alaska and westernCanada. The genus is placed as a separate family, order and class among the mosses.

OEDIPODIUM

Oedipodium is the only genus of moss in the family Oedipodiaceae; it contains the single species Oedipodium griffithianum. This species is distributed in cooler climates of Eurasia, North and South America, and islands in the northernAtlantic.[2]

The relationship of Oedipodium to other mosses has been much debated. Previously, the taxon has been included with theFunariales or the Splachnales. However, characteristics of the protonemata and asexual propagation, along with molecular evidence, point to a closer

relationship with the Tetraphidaceae.POLYTRICHACEAE

The Polytrichaceae is a common family of mosses. Members of this family tend to be larger than other mosses with a thickened central stem and a rhizome. The leaves have a midrib that bears lamellae on the upper surface. Species in this group are dioicous. Another characteristic that identifies them is that they have from 32 to 64 peristome teeth in their sporangium.

TETRAPHIDACEAE

The Tetraphidaceae is a family of mosses. It includes only the two genera Tetraphis and Tetrodontium, each with twospecies.

BRYOPSIDA

The Bryopsida constitute the largest class of mosses, containing 95% of all moss species. It consists of approximately 11,500 species, common throughout the whole world.The group is distinguished by having spore capsules with teeth that are arthrodontous; the teeth are separate from each other and jointed at the base where they attach to the opening of the capsule.[2] These teeth are exposed when the covering operculum falls off. In other groups of mosses, the capsule is either nematodontous with an attached operculum, or else splits open

without operculum or teeth.

DIVISION PSILOPHYTA (PSILOTUM)

Primitive leafless vascular plants bearing 3-lobed sporangia on branches; includes the unusual wisk fern (Psilotum nudum; plants such as this (including treelike forms as tall as telephone poles) were abundant in ancient swamplands 300 million years ago.

CLASS

RHYNIOPSIDA

Rhyniopsida is a class of extinct early vascular plants, with one family, Rhyniaceae, found in the Early Devonian(around 416 to 398 million years ago). They are polysporangiophytes, since their sporophytes consisted of branched stems bearing sporangia (spore-forming organs). They lacked leaves or true roots but did have simple vascular tissue. The class was formerly placed in a division called Rhyniophyta (see Polysporangiophyte: Taxonomy for alternative names). This group was found not to be monophyletic since some specimens which had been included are now known to lack vascular tissue. Some former members have been placed in the class Horneophytopsida, which is defined as lacking true vascular tissue. Currently, Rhyniopsida includes the genera Huvenia, Rhynia, and Stockmansella, all from the Devonian.One of the most important radiations for land plants occurred in the early Devonian (Pragian), when the first rhyniophytes appear in the fossil record, making this rich fossil discovery of major importance to paleobotany.

HORNEOPHYTOPSIDA

Horneophytopsida is a class of extinct plants which consisted of branched stems without leaves, true roots or vascular tissue, found from the Late Silurian to the Early Devonian (around 420 to 400 million years ago). They are the simplest known polysporangiophytes, i.e. plants with sporophytes bearing many spore-forming organs (sporangia) on branched stems. They were formerly classified among the "rhyniophytes", but it was later found that some of the original members of the group had simple vascular tissue and others did not.[1]

In 2004, Crane et al. published a cladogram for the polysporangiophytes in which the Horneophytopsida are shown as the sister group of all other polysporangiophytes.[2] One other former "rhyniophyte", Aglaophyton, is also placed outside the tracheophyte clade, as it did not possess true vascular tissue (in particular did not have tracheids), although its conducting tissue is more complex that than of the Horneophytopsida.

COOKSONIA

Cooksonia is an extinct grouping of primitive land plants. The earliest Cooksonia date from the middle of the Silurian (the Wenlock epoch);[1] the group continues to be an important component of the flora until the Early Devonian, a total time span of 428 to 398 million years ago. For historical reasons, while Cooksonia fossils are distributed globally, most type specimens come from Britain.

ZOSTEROPHYLLOPSIDA

The Zosterophyllopsida or zosterophylls are a class of extinct plants. The taxon was first established by Banks in 1975 as the subdivision Zosterophyllophyta, also called Zosterophyllophytina. They were among the first vascular plants in the fossil record, and had a world-wide distribution. They were probably stem-group lycophytes, forming a sister group to the ancestors of the living lycophytes. By the late Silurian (late Ludlovian, about 420 million years ago) a diverse assemblage of species existed, examples of which have been found fossilised in what is now Bathurst Island inArctic Canada.

PSILOPHYTON

Psilophyton is a fossil genus which currently contains seven species known mostly from compression, impression and some permineralized anatomy. Most specimens come from northern Maine, Gaspé Bay in Quebec, New Brunswick and theCzech Republic. P. princeps, P. forbesii, P. dapsile, P. charientos, P. dawsonii, P. microspinosum, P. kräuselii and P. crenulatum are the currently accepted members of the genus Psilophyton. Variation within the genus is significant. The average specimen was 60 cm or more tall.

EUPHYLLOPHYTINA

Euphyllophytina, the euphyllophytes, is a taxon – sometimes unranked, sometimes placed at the informal rank of subdivision – within the tracheophytes. It is sister to subdivision Lycopodiophyta. Euphyllophytina contains the two groups Spermatophytes (seed plants) and Monilophytes (ferns), as well as a number of extinct fossil taxa. The division of the extant tracheophytes into three monophyletic lineages is supported in multiple molecular studies. Other researchers state that taking fossils into account leads to different conclusions, for example that the ferns are not monophyletic.

DIVISION LYCOPHYTA (CLUB MOSSES)

Minute "true" leaves superficially resembling a moss; terminal, stalked spore-bearing strobilus in Lycopodium; in Selaginella male and female sporangia are produced in the leaf axils; also includes the bizarre quillworts (Isoetes); many fossil forms (some tree-like) dating back 300 million years ago; Lycopodium spores used for dust explosion demonstrations, and were used for flash powder prior to flash bulbs and strobe lights.

CLASS

ISOETOPSIDA

The Isoetopsida is a class of the Lycopodiophyta. All living plants belong to the genus Selaginella in the Selaginellales or to Isoetes in the order Isoetales. In the past, members of this group have sometimes been placed in the class Isoetopsida, sometimes in the Selaginellopsida or Lycopodiopsida. There are about 700 species ofSelaginella and 140-150 species of Isoetes, with a cosmopolitan distribution but often scarce to rare. Some botanistssplit Isoetes, separating two South American species into the genus Stylites.[2]

The most famous group within the Isoetopsida is the "scale trees" (order Lepidodendrales), which includeLepidodendron. These massive trees flourished in marshlands of the Carboniferous. Quillworts are considered by some to be the last remnant of such fossil trees, with which they share some unusual features including the development of both wood and bark, a modified shoot system acting as roots, bipolar growth, and an upright stance.

LYCOPODIOPSIDA

Lycopodiopsida is a class of plants often loosely grouped as the fern allies. Traditionally the group included not only the clubmosses and firmosses, but also the spikemosses (Selaginella and relatives) and the quillworts (Isoetes and relatives). However, the later are now usually separated off into a separate class, Isoetopsida.Clubmosses are thought to be structurally similar to the earliest vascular plants, with small, scale-like leaves, homosporous spores borne in sporangia at the bases of the leaves, branching stems (usually dichotomous), and generally simple form.The Class Lycopodiopsida as interpreted here contains a single living order, the Lycopodiales, and a single extinct order, the Drepanophycales.

DIVISION SPHENOPHYTA (HORSETAILS)

Primitive vascular plant group of the Carboniferous Period (300 million years ago) with jointed stems, whorls of tiny scale-like leaves at the nodes, and a terminal spore cone (strobilus); some species with dense branches at nodes, apparently resembling a bushy horse's tail to some botanists; also called "scouring rushes" because the silica-impregnated stems were used to clean pots and pans; many fossils, including tree-like forms dating back 300 million years ago; the present-day genus Equisetum is a living fossil with several species that are the only living representatives of this ancient group of vascular plants.

EQUISETALES

The Equisetales is an order of pteridophytes with only one living genus Equisetum (horsetails), of the family Equisetaceae. The fossil record includes additional extinct species in the Equisetaceae and the extinct familiesCalamitaceae and Archaeocalamitaceae.

DIVISION PTEROPHYTA (FERNS)

Leaves (fronds) with sporangia clusters (sori) on the underside; fronds arising from subterranean, creeping rhizomes and from trunks of tree-like forms (called tree ferns); includes the orders Filicales (true ferns Adiantum, Pteridium, Dryopteris,Polypodium, Polystichum, Pellaea, etc.), Marsileales (clover-leaf ferns Marseliaand pillworts Pillularia), Ophioglossales (adder's tongue fern Ophioglossum), and Salviniales (water ferns Azolla and Salvinia). Sometimes these latter "ferns" are called "fern allies" because they belong to different orders; i.e. they do not belong to the order Filicales (the order of true ferns).

 An "air fern" (Sertularia argenta). This is NOT a true fern. It is the skeletal remains of a dead marine hydrozoan which has been dyed green. Hydrozoans belong to the animal Phylum Cnidaria (Class Hydrozoa), and include many marine and freshwater species. [True corals and sea anemones belong to the Class Anthozoa and jellyfish belong to the Class Scyphozoa.] Hydrozoans form intricately branched colonies attached to rocks and ocean bottoms. The fernlike branches are composed of numerous, minute, chitinous chambers where the individual animals once lived. When the colony was alive, a tentacle-bearing polyp occupied each chamber (hydrotheca). The "air fern" does not grow because it is dead. In fact, it has no roots or leaves and the green coloring will dissolve if you soak the air fern in water. Most commercial air ferns are collected by trawlers in the North Sea. They are sold as a curiosity or decorative "indoor plant," and as underwater decorations for aquaria.

Note: Although it has jellyfish characteristics, the infamous Portuguese man-of-war (Physelia) actually belongs to the Class Hydrozoa (Order Siphonophora). It is a large colonial animal with a bladderlike float or air sac and long stinging tentacles that hang down in the water. An accidental encounter with one of of these creatures can be a painful and dangerous experience for a swimmer.

CLASSES

PSILOTOPSIDA

Psilotopsida is a class of fern-like plants.[1] It should not be confused with the obsolete class Psilophytopsida. As circumscribed by Smith et al. (2006) Psilotopsida contains two families, Psilotaceae and Ophioglossaceae, placed in orders Psilotales and Ophioglossales, respectively. The affinities of these two groups have long been unclear and a close relationship between them has only recently been confirmed through molecular systematic studies. Psilotopsida is the sister-group to all other ferns (including Marattiaceae and Equisetaceae).

MARATTIOPSIDA

Class Marattiopsida is a group of ferns containing a single order, Marattiales, and family, Marattiaceae. Class Marattiopsida diverged from other ferns very early in their evolutionary history and are quite different from many plants familiar to people in temperate zones. Many of them have massive, fleshy rootstocks and the largest known fronds of any fern. The Marattiaceae is one of two groups of ferns traditionally known as eusporangiate fern, meaning that thesporangium is formed from a group of cells vs the leptosporangium in which there is a single initial cell. There have long been four traditional extant genera (Angiopteris, Christensenia, Danaea and Marattia), but recent genetic/cladistic analysis  has determined the genus Marattia to be paraphyletic, and the genus has been split into three genera, the two new ones being Eupodium and Ptisana. This fern group has a long fossil history with many extinct taxa (Psaronius, Asterotheca, Scolecopteris, Eoangiopteris, Qasimia, Marantoidea, Danaeites, Marattiopsis, etc.)

LEPTOSPORANGIATE FERN

Leptosporangiate ferns are the largest group of living ferns. They are often considered to be the classPteridopsida or Polypodiopsida, although other classifications assign them a different rank. The leptosporangiate ferns are one of the four major groups of ferns, with the others being Marattiopsida,Equisetopsida (horsetails), and Psilotopsida (whisk ferns and ophioglossoid ferns).

There are approximately 9000 species of living leptosporangiate ferns, compared with about 260 for all other ferns put together. Almost a third of leptosporangiate fern species are epiphytes. These ferns are called leptosporangiate because their sporangia arose from a single epidermal cell and not from a group of cells as in eusporangiate ferns. The sporangia are typically covered with a scale called theindusium, which can cover the whole sorus, but can also be strongly reduced. Many leptosporangiate ferns have an annulus around the sporangium, which ejects the spores.

HYMENOPHYLLACEAE

The Hymenophyllaceae (filmy ferns and bristle ferns) is a family of seven genera and over 600 species of ferns, with a subcosmopolitan distribution, but generally restricted to very damp places or to locations where they are wetted by spray from waterfalls or springs. A recent fossil find shows that ferns of Hymenophyllaceae have existed since at least the Upper Triassic.[1]

The great majority of the species are found in tropical rainforests, but some also occur in temperate rainforests(particularly New Zealand, with 25 species) and slightly drier forest regions. In Europe they are restricted to theAtlantic Ocean fringes of the continent, notably in the Azores, Ireland, and western Great Britain, but one species (Hymenophyllum tunbrigense) locally east to Luxembourg, another (H. wilsonii) so far north as West Norway, Faeroesand South Iceland, while in North America, they are restricted to the humid eastern third of the continent.

GLEICHENIALES

The ferns of the order Gleicheniales are – like all ferns and the related horsetails – sometimes placed in aninfradivision Monilophytes of subdivision Euphyllophytina, allowing for more precise phylogenetic arrangement of the tracheophytes. More conventionally, the name Pteridophyta, ranked as a division, is used in lieu of the Monilophytes.[1] The Gleicheniales showed up in the fossil record at least as early as the Cretaceous.[2]

These ferns are characterized by root steles having 3–5 protoxylem poles and antheridia with 6–12 narrow, twisted or curved cells in their walls[1]. Otherwise, their habitus is highly diverse, including plants with the typical fern fronds, others whose leaves resemble those of palm trees, and yet others again which have undivided leaves. They are tropical ferns, most diverse in Asia and the Pacific region.

SCHIZAEALES

Schizaeales is an order of fern (class Pteridopsida). The ferns in this order were once all lumped into the family Schizaeaceae in the old order Filicales. However, although they are demonstrably related, these ferns differ markedly, and so three groups have now been elevated to family status:The family Schizaeaceae are generally small ferns with forking fronds and a distinctive, somewhat non-fern-like, appearance.The family Anemiaceae look very fern-like and are typically terrestrial or epipetric.The family Lygodiaceae, or Climbing Ferns, look very ferny but are highly distinctive in their growth habit: the rachis of the frond is long and flexible, with indeterminate growth, so that the fronds form climbing or trailing vines.At one time some workers believed the water ferns (order Salviniales) to be allied to this order because of certain structural similarities, but modern cladistic studies have ruled out any special alliance.

CYATHEALES

The order Cyatheales is a taxonomic division of the fern subclass, Cyatheatae, which includes the tree ferns. No clear morphological features characterize all of the Cyatheales,

but DNA sequence data indicates that the order ismonophyletic. Some species in the Cyatheales have tree-like growth forms, but others have creeping rhizomes(stems). Some species have scales on the stems and leaves, while others have hairs. However, most plants in the Cyatheales are tree ferns and have trunk-like stems up to 20 meters tall. It is unclear how many times the tree form has evolved and been lost in the order.

POLYPODIALES

The order Polypodiales encompasses the major lineages of polypod ferns, which comprise more than 80% of today's fern species. They are found in many parts of the world including tropical, semitropical and temperate areas. The characteristics of this group include: sporangia with a vertical annulus interrupted by the stalk and stomium; indusialaterally or centrally attached (or lost); gametophytes green, chordate, and surficial .Polypodiales may be regarded as one of the most evolutionarily advanced orders of monilophytes (ferns), based on recent genetic analysis. They arose and diversified about 100 million years ago, probably subsequent to the diversification of the angiosperms. 

DIVISION CYCADOPHYTA (CYCADS)

Palm-like plants with large seed and pollen cones; flourished during the days of the dinosaurs and undoubtedly were a major food supply for herbivorous dinosaurs; cycads were so numerous in Mesozoic times that this era is often called the Age of Cycads and Dinosaurs; cycads are dioecious species with pollen cones and seed cones produced on separate male and female individuals; in some species, the enormous pollen and seed cones may reach 3 feet in length and may weigh up to 90 pounds, the largest of all living cone-bearing plants.

CLASS

CYCAS

Cycas is the type genus and the only genus currently recognised in the cycad family Cycadaceae. About 95 species are currently accepted. The best-known species is Cycas revoluta, widely cultivated under the name "Sago Palm" or "King Sago Palm" due to its palm-like appearance although it is not a true palm. The generic name comes from GreekKoikas, and means "a kind of palm".The genus is native to the Old World, with the species concentrated around the equatorial regions. It is native to eastern and southeastern Asia including the Philippines with 10 species (9 of which are endemic), eastern Africa (includingMadagascar), northern Australia, Polynesia, and Micronesia. Australia has 26 species, while the Indo-Chinese area has about 30. The northernmost species (C. revoluta) is found at 31°N in southern Japan. The southernmost (C. megacarpa) is found at 26°S in southeast Queensland, Australia.The plants are dioecious, and the family Cycadaceae is unique among the cycads in not forming seed cones on female plants, but rather a group of leaf-like structures each with seeds on the lower margins, and pollen cones on male individuals.

STANGERIACEAE

Stangeriaceae is the smallest family of cycads, both in number of living and fossil species. The family contains only two living genera, Stangeria and Bowenia, though the latter genus has been recommended for placement in a separate family by itself.The family is recognized by having vascularized stipules, and by lacking cataphylls, or producing them irregularly. These unusual characters led to the original description of Stangeria as a fern, and it was only when seeds were later produced on the plant that its true affinities were realized. Though today the family occurs only in South Africa and Queensland, Australia, fossils are known from Jurassicsediments in Argentina and the British Isles. Recent cladistic studies suggest that the fossil taxon Mesodescoleamay also have affinities with the Stangeriaceae. This highly lobed fossil leaf from the Lower Cretaceous has only been found in Argentina.

DIOON

Dioon is a plant genus of 11 accepted species. They are cycads in the family Zamiaceae, and native to Mexico,Honduras, and Nicaragua. Their habitats include tropical forests, pine-oak forest, and dry hillsides, canyons and coastal dunes. In North America, the Dioon can be seen growing from southern Florida up to Savannah,Georgia.

Dioons are dioecious, palmlike shrubs with cylindrical stems, usually with many leaves. Leaf bases are persistent or shedding to leave smooth bark. The genus is commonly divided into two groups of distinct morphology. The first includes D. mejiae, D. rzedowskii, and D. spinulosum, "characterized generally by large fronds, well-developed trunks, and massive cones". The second group contains D. califanoi, D. caputoi, D. edule, D. holmgrenii, D. merolae,D. purpusii, D. sonorense, and D. tomasellii, which are "less robust, with generally shorter trunks, considerably shorter fronds, and smaller cones".The leaves are pinnate, spirally arranged, interspersed with cataphylls, with leaflets not articulated and lacking a midrib. The lower leaflets are often reduced to spines. The sporophylls are not in vertical rows in cones, and themegasporophyll apices are broadly flattened, upturned, and overlapping.

MACROZAMIA

Macrozamia is a genus of 38-40 species of cycads, in the family Zamiaceae, endemic to Australia. The majority of the species occur in eastern Australia in southeast Queensland and New South Wales, with one species in theMacdonnell Ranges of Northern Territory and three in southern Western Australia. The common name Burrawang, originally referring to M. communis in the Daruk Australian Aboriginal language, is often used for all the species in the genus.

LEPIDOZAMIA

Lepidozamia is a genus of two species of cycad, native to Australia. The name, derived from the Greek word lepidos, meaning scaly, refers to the scale-like structure of the stem and leaf bases. They are native to rainforest climates in eastern Queensland and eastern New South Wales. They have a chromosome number of 2n = 18.CERATOZAMIA

Ceratozamia is a genus of New World cycads in the family Zamiaceae. The genus contains 16-18 currently living species and one or two fossil species. Most species are endemic to mountainous areas of Mexico, while C. robustaextends into the mountains of Guatemala and Belize. The genus name comes from the Greek ceras, meaning horn, which refers to the paired, spreading horny projections on the male and female sporophylls of all species. Many species have extremely limited ranges, and almost all described species are listed as vulnerable, endangered, or critically endangered by the IUCN Red List. Illegal plant poaching has posed a major threat to Ceratozamia species.The plants are dioecious , with a globose or cylindrical stem, rarely dichotomously branched, that may be underground or emergent. Several species produce basal shoots or suckers. The leaves are pinnately compound, straight, and spirally arranged. Leaf bases are usually deciduous but sometimes persistent. The petioles and rachisoften have spines, though there may be very few to none. Leaflets are simple, entire, and articulate at the base, with parallel side veins and no distinct central vein. Male cones are cylindrical, upright, hairy, and stalked. Female cones are stalked or sessile, erect, and have short hairs. Seeds are oblong or elliptical, with a fleshy whitish outer coat.Most species inhabit mountainous areas at 800-1000 m elevation, on sheltered slopes in moist forests. These forests range from tropical rainforests that are always wet, to pine-oak forests with alternating wet and dry seasons. There is a noticeable correlation between characteristics of species and the wetness or dryness of the habitat. Species with broad, thin leaflets live in wet habitats, and species with narrow, thick leaflets live in climates with wet and dry seasons.No formal classification of the genus currently exists, but studies by researchers have shown that there are two major groups within the genus. The first group contains seven described species. Species in this group have small cones and thin, broad, asymmetrical leaflets that taper gradually toward the base. Species of the second group have cones that are small to large. Leaflets are narrow, thin to thick in texture, symmetrical, and do not taper toward the base. This group contains nine species.

DIVISION GINKGOPHYTA (MAIDENHAIR TREE)

Seeds borne in pairs on dwarf shoots; leaves similar in shape to the maidenhair fern (Adiantum); a true living fossil dating back 185 million years; only one living representative Ginkgo biloba.

CLASS

GINKGO

Ginkgo is a genus of highly unusual non-flowering plants with one extant species, G. biloba, which is regarded as aliving fossil.

PrehistoryThe Ginkgo is a living fossil, with fossils recognisably related to modern Ginkgo from the Permian, dating back 270 million years. The most plausible ancestral group for the order Ginkgoales is the Pteridospermatophyta, also known as the "seed ferns," specifically the order Peltaspermales. The closest living relatives of the clade are the cycads,[3]which share with the extant G. biloba the characteristic of motile sperm. Fossils attributable to the genus Ginkgo first appeared in the Early Jurassic, and the genus diversified and spread throughout Laurasia during the middle Jurassic andEarly Cretaceous. It declined in diversity as the Cretaceous progressed, and by the Paleocene, Ginkgo adiantoides was the only Ginkgo species left in the Northern Hemisphere while a markedly different (and poorly documented) form persisted in the Southern Hemisphere. At the end of the Pliocene, Ginkgo fossils disappeared from the fossil record everywhere except in a small area of central China where the modern species survived. It is doubtful whether the Northern Hemisphere fossil species of Ginkgo can be reliably distinguished. Given the slow pace of evolution and morphological similarity between members of the genus, there may have been only one or two species existing in the Northern Hemisphere through the entirety of the Cenozoic: present-day G. biloba (including G. adiantoides) and G. gardneri from the Paleocene of Scotland.