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Embryophyta

Embryophyta

- Non-vascular plants (bryophytes)
- Marchantiophyta - liverworts
- Anthocerotophyta - hornworts
- Bryophyta - mosses
- Vascular plants (tracheophytes)
- Lycopodiophyta - clubmosses
- Equisetophyta - horsetails
- Pteridophyta - "true" ferns
- Psilotophyta - whisk ferns
- Ophioglossophyta - adders'-tongues
- Seed plants (spermatophytes)
- †Pteridospermatophyta - seed ferns
- Pinophyta - conifers
- Cycadophyta - cycads
- Ginkgophyta - ginkgo
- Gnetophyta - gnetae
- Magnoliophyta - flowering plants The embryophytes are the most familiar group of plants, including trees, flowers, ferns, mosses, and various others. All are complex multicellular organisms with specialized reproductive organs and, with very few exceptions, they obtain their energy through photosynthesis, i.e. by absorbing light, and synthesize food from carbon dioxide. They may be distinguished from multicellular algae by having sterile tissue within the reproductive organs. Further, embryophytes are primarily adapted for life on land, although some are secondarily aquatic. Accordingly they are often called land plants. Embryophytes developed from complex green algae during the Palaeozoic era. Their closest living relatives are the Charales or stoneworts. These algae undergo an alternation between haploid and diploid generations, respectively called gametophytes and sporophytes. In the first embryophytes, however, the sporophytes became very different in structure and function, remaining small and dependent on the parent for their entire brief life. Such plants are called bryophytes; they include three surviving groups:
- Bryophyta (mosses)
- Anthocerotophyta (hornworts)
- Marchantiophyta (liverworts) All bryophytes are relatively small and are usually confined to moist environments, relying on water to disperse their spores. Other plants better adapted to terrestrial conditions appeared during the Silurian, and during the Devonian they diversified and spread to many different land environments. These are called vascular plants or tracheophytes. They have vascular tissues or tracheids, which transport water throughout the body, and an outer layer or cuticle that resists desiccation. In most the sporophyte is the dominant individual, and develops true leaves, stems, and roots, while the gametophyte remains very small. Many vascular plants still reproduce using spores, including the following extant groups:
- Lycopodiophyta (clubmosses)
- Equisetophyta (horsetails)
- Psilotophyta (whisk ferns)
- Ophioglossophyta (adders'-tongues and grape-ferns)
- Pteridophyta (ferns) Other groups, which first appeared towards the end of the Palaeozoic, reproduce using desiccation-resistant capsules called seeds. They are accordingly are called spermatophytes or seed plants. In these forms the gametophyte is completely reduced, taking the form of single-celled pollen and ova, and the sporophyte begins its life enclosed within the seed. Some seed plants may survive in extremely arid conditions. They include the following extant groups:
- Cycadophyta (Cycads)
- Ginkgophyta (Ginkgo)
- Pinophyta (Conifers)
- Gnetophyta (Gnetae)
- Magnoliophyta (Flowering plants) The first four groups are referred to as gymnosperms, since the embryonic sporophyte is not enclosed until after pollination. In contrast, the flowering plants or angiosperms the pollen has to grow a tube to penetrate the seed coat. They were the last major group of plants to appear, developing from gymnosperms during the Jurassic and spreading rapidly during the Cretaceous. They are the predominant group of plants in most terrestrial biomes today. Note the higher-level classification of plants varies considerably. Some authors have restricted the kingdom Plantae to include only embryophytes, others have given them various names and ranks. The groups listed here are often considered divisions or phyla, but have also been treated as classes, and they are occasionally compressed into as few as two divisions. On a microscopic level, embryophyte cells remain very similar to those of green algae. They are eukaryotic, with a cell wall composed of cellulose and plastids surrounded by two membranes. These usually take the form of chloroplasts, which conduct photosynthesis and store food in the form of starch, and characteristically are pigmented with chlorophylls a and b, generally giving them a bright green color. Embryophytes also generally have an enlarged central vacuole or tonoplast, which maintains cell turgor and keeps the plant rigid. They lack flagella and centrioles except in certain gametes.

References

- Kenrick, Paul & Crane, Peter R. (1997). The Origin and Early Diversification of Land Plants: A Cladistic Study. Washington, D. C.: Smithsonian Institution Press. ISBN 1-56098-730-8.
- Raven, Peter H., Evert, Ray F., & Eichhorn, Susan E. (2005). Biology of Plants (7th ed.). New York: W. H. Freeman and Company. ISBN 0-7167-1007-2.
- Stewart, Wilson N. & Rothwell, Gar W. (1993). Paleobotany and the Evolution of Plants (2nd ed.). Cambridge: Cambridge University Press. ISBN 0-521-38294-7.
- Taylor, Thomas N. & Taylor, Edith L. (1993). The Biology and Evolution of Fossil Plants. Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-651589-4. sort10 Embryophyta sort10 Embryophyta ja:植物

Bryophyte

Bryophytes are embryophyte plants ('land plants') that are nevertheless non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They neither flower nor produce seeds, reproducing via spores.

Bryophyte classification

spore There are three groups, the Marchantiophyta (liverworts), Anthocerotophyta (hornworts), and Bryophyta (mosses). Modern studies generally show one of two patterns. In one of these patterns, the liverworts were the first to diverge, followed by the hornworts, while the mosses are the closest living relatives of the vascular plants. In the other pattern, the hornworts were the first to diverge, followed by the vascular plants, while the mosses are the closest living relatives of the liverworts. Originally the three groups were brought together as the three classes of division Bryophyta. However, since the three groups of bryophytes form a paraphyletic group, they now are placed in three separate divisions.

Bryophyte sexuality

These plants are generally gametophyte-oriented; that is, the normal plant is the haploid gametophyte, with the only diploid structure being the sporangium in season. As a result, bryophyte sexuality is very different from that of other plants. There are two basic categories of sexuality in bryophytes:
- dioicous - These plants produce only antheridia (male organs) or archegonia (female organ) on a single plant body.
- monoicous - These plants produce both antheridia and archegonia on the same plant body. Some bryophyte species may be either monoicous or dioicous depending on environmental conditions. Other species grow exclusively with one type of sexuality. Notice that these terms are not the same as monoecious and dioecious, which refer to whether or not a sporophyte plant bears one or both kinds of gametophyte. Those terms apply only to seed plants.

References

- Chopra, R. N. & Kumra, P. K. (1988). Biology of Bryophytes. New York: John Wiley & Sons. ISBN 0-470-21359-0.
- Crum, Howard (2001). Structural Diversity of Bryophytes. Ann Arbor: University of Michigan Herbarium. ISBN 0-9620733-4-2.
- Goffinet, Bernard. (2000). Origin and phylogenetic relationships of bryophytes. In A. Jonathan Shaw & Bernard Goffinet (Eds.), Bryophyte Biology, pp. 124-149. Cambridge: Cambridge University Press. ISBN 0-521-66097-1.
- Oostendorp, Cora (1987). The Bryophytes of the Palaeozoic and the Mesozoic. Bryophytorum Bibliotheca, Band 34. Berlin & Stuttgart: J. Cramer. ISBN 3-443-62006-X.
- Prihar, N. S. (1961). An Introduction to Embryophyta: Volume I, Bryophyta (4th ed.). Allahabad: Central Book Depot.
- Raven, Peter H., Evert, Ray F., & Eichhorn, Susan E. (2005). Biology of Plants (7th ed.). New York: W. H. Freeman and Company. ISBN 0-7167-1007-2.
- Schofield, W. B. (1985). Introduction to Bryology. New York: Macmillan. ISBN 0-02-949660-8.
- Watson, E. V. (1971). The Structure and Life of Bryophytes (3rd ed.). London: Hutchinson University Library. ISBN 0-09-109301-5. sort11 Bryophyta Category: Bryophytes Category: cryptogams ja:センタイ類 simple:Bryophyta

Hornwort

:This is an article about the non-vascular plants. The name Hornwort is also often applied to the aquatic plant Ceratophyllum demersum in the family Ceratophyllaceae Anthocerotaceae
- Anthoceros
- Folioceros
- Leiosporoceros
- Phaeoceros
- Sphaerosporoceros Dendrocerotaceae
- Dendroceros
- Megaceros
- Notoceros Notothyladaceae
- Notothylas Hornworts are a group of bryophytes, or non-vascular plants, comprising the division Anthocerotophyta. The common name refers to the elongated horn-like structure, which is the sporophyte. The flattened, green plant body of a hornwort is the gametophyte plant. Hornworts may be found world-wide, though they tend to grow only in places that are damp or humid. Some species grow in large numbers as tiny weeds in the soil of gardens and cultivated fields. Large tropical and sub-tropical species of Dendroceros may be found growing on the bark of trees.

Description

The plant body of a hornwort is a haploid gametophyte stage. This stage usually grows as a thin rosette or ribbon-like thallus between one and five centimeters in diameter. Each cell of the thallus usually contains just one chloroplast per cell. In most species, this chloroplast is fused with other organelles to form a large pyrenoid that both manufactures and stores food. This particular feature is very unusual in land plants, but is common among algae. Many hornworts develop internal mucilage-filled cavities when groups of cells break down. These cavities are invaded by photosynthetic cyanobacteria, especially species of Nostoc. Such colonies of bacteria growing inside the thallus give the hornwort a distinctive blue-green color. There may also be small slime pores on the underside of the thallus. These pores superficially resemble the stomata of other plants. stomata The horn-shaped sporophyte grows from an archegonium embedded deep in the gametophyte. Hornworts sporophytes are unusual in that the sporophyte grows from a meristem near its base, instead of from its tip the way other plants do. Unlike liverworts, most hornworts have true stomata on the sporophyte as mosses do. The exceptions are the genera Notothylas and Megaceros, which do not have stomata. When the sporophyte is mature, it has a multicellular outer layer, a central rod-like columella running up the center, and a layer of tissue in between that produces spores and pseudo-elaters. The pseudo-elaters are multi-cellular, unlike the elaters of liverworts. They have helical thickenings that change shape in response to drying out, and thereby twist in and thereby help to disperse the spores. Hornwort spores are relatively large for bryophytes, measuring between 30 and 80 um in diameter or more. The spores are polar, usually with a distinctive Y-shaped tri-radiate ridge on the proximal surface, and with a distal surface ornamented with bumps or spines.

Life cycle

The life of a hornwort starts from a haploid spore. In most species, there is a single cell inside the spore, and a slender extension of this cell called the germ tube germinates from the proximal side of the spore. The tip of the germ tube divides to form an octant of cells, and the first rhizoid grows as an extension of the original germ cell. The tip continues to divide new cells, which produces a thalloid protonema. By contrast, species of the family Dendrocerotaceae may begin dividing within the spore, becoming multicellular and even photosynthetic before the spore germinates. In either case, the protonema is a transitory stage in the life of a hornwort. photosynthetic From the protonema grows the adult gametophyte, which is the persistent and independent stage in the life cycle. This stage usually grows as a thin rosette or ribbon-like thallus between one and five centimeters in diameter, and several layers of cells in thickness. It is green or yellow-green from the chlorophyll in its cells, or bluish-green when colonies of cyanobacteria grow inside the plant. When the gametophyte has grown to its adult size, it produces the sex organs of the hornwort. Most plants are monoicous, with both sex organs on the same plant, but some plants (even within the same species) are dioicous, with separate male and female gametophytes. The female organs are known as archegonia (singular archegonium) and the male organs are known as antheridia (singular antheridium). Both kinds of organs develop just below the surface of the plant and are only later exposed by disintegration of the overlying cells. The biflagellate sperm must swim from the antheridia, or else be splashed to the archegonia. When this happens, the sperm and egg cell fuse to form a zygote, the cell from which the sporophyte stage of the life cycle will develop. Unlike all other bryophytes, the first cell division of the zygote is longitudinal. Further divisions produce three basic regions of the sporophyte. At the bottom of the sporophyte (closest to the interior of the gametophyte), is a foot. This is a globular group of cells that receives nutrients from the parent gametophyte, on which the sporophyte will spend its entire existence. In the middle of the sporophyte (just above the foot), is a meristem that will continue to divide and produce new cells for the third region. This third region is the capsule. Both the central and surface cells of the capsule are sterile, but between them is a layer of cells that will divide to produce pseudo-elaters and spores. These are released from the capsule when it splits lengthwise from the tip.

Classification of Hornworts

Hornworts were traditionally considered a class within the Division Bryophyta (bryophytes). However, it now appears that this group is paraphyletic, so the hornworts tend to be given their own division, called Anthocerotophyta. The Bryophyta is now restricted to include only mosses. There is a single class of hornworts, called Anthocerotopsida, or traditionally Anthocerotae. This class includes a single order of hornworts (Anthocerotales) in this classification scheme. In some other classification schemes, a second order Notothyladales (containing only the genus Notothylas) is recognized because of the unique and unusual features present in that group. Among land plants, hornworts appear to be one of the oldest surviving groups. There are only about 100 species known, but new species are still being discovered. The number and names of genera are a current matter of investigation, and several competing classification schemes have been published since 1988. genera

Families and genera

Anthocerotaceae
- Anthoceros
- Folioceros
- Leiosporoceros
- Phaeoceros
- Sphaerosporoceros Dendrocerotaceae
- Dendroceros
- Megaceros
- Notoceros Notothyladaceae
- Notothylas

References

- Chopra, R. N. & Kumra, P. K. (1988). Biology of Bryophytes. New York: John Wiley & Sons. ISBN 0-470-21359-0.
- Grolle, Riclef (1983). "Nomina generica Hepaticarum; references, types and synonymies". Acta Botanica Fennica 121, 1-62.
- Hasegawa, J. (1994). "New classification of Anthocerotae". J. Hattori Bot. Lab 76: 21-34.
- Renzaglia, Karen S. (1978). "A comparative morphology and developmental anatomy of the Anthocerotophyta". J. Hattori Bot. Lab 44: 31-90.
- Renzaglia, Karen S. & Vaughn, Kevin C. (2000). Anatomy, development, and classification of hornworts. In A. Jonathan Shaw & Bernard Goffinet (Eds.), Bryophyte Biology, pp. 1-20. Cambridge: Cambridge University Press. ISBN 0-521-66097-1.
- Schofield, W. B. (1985). Introduction to Bryology. New York: Macmillan.
- Schuster, Rudolf M. (1992). The Hepaticae and Anthocerotae of North America, East of the Hundredth Meridian, Volume VI. Chicago: Field Museum of Natural History.
- Smith, Gilbert M. (1938). Cryptogamic Botany, Volume II: Bryophytes and Pteridophytes. New York: McGraw-Hill Book Company.
- Watson, E. V. (1971). The Structure and Life of Bryophytes (3rd ed.). London: Hutchinson University Library. ISBN 0-09-109301-5.

External links

- [http://www3.uakron.edu/biology/hornworts/hornworts.html Hornwort Web Portal]
- [http://koning.ecsu.ctstateu.edu/Plant_Biology/hornwort.html Hornwort biology information]
- [http://www.ucmp.berkeley.edu/plants/anthocerotophyta.html Anthocerotophyta description and fossil history at UCMP]
- [http://www.natureserve.org/explorer/speciesIndex/Class_Anthocerotopsida_106589_1.htm Hornwort species in the United States and Canada]
- [http://www.peripatus.gen.nz/Taxa/Bryophyta/NZAnthocerotae.html New Zealand Anthocerotae] ---- Category: Plants Category: Bryophytes Category: cryptogams

Moss

:This is an article about the plant. For other uses, see Moss (disambiguation)
- Sphagnidae
- Andreaeidae
- Tetraphidae
- Polytrichidae
- Archidiidae
- Buxbaumiidae
- Bryidae Bryidae Mosses are small plants that are rarely taller than 2 inches (50mm). They typically grow close together in clumps or mats in damp or shady locations. They do not have flowers and their simple leaves cover the thin wiry stems. At certain times mosses produces spore capsules which may appear as beak-like capsules borne aloft on thin stalks.

Overview

Botanically, mosses are bryophytes, or non-vascular plants. They can be distinguished from the apparently similar liverworts (Marchantiophyta or Hepaticae) by their multi-cellular rhizoids. Other differences are not universal for all mosses and all liverworts but the presence of clearly differentiated stem and leaves, the lack of deeply lobes or segmented leaves,and the absence of leaves arranged in three ranks all point to the plant being a moss. The division Bryophyta formerly included not only mosses, but also liverworts and hornworts. These other two groups of bryophytes now are often placed in their own divisions. Aside from lacking a vascular system, they have a gametophyte-dominant life cycle, i.e. the plant's cells are haploid for most of its life cycle. Sporophytes (i.e. the diploid body) are short-lived and dependent on the gametophyte. This is in contrast to the pattern exhibited by most "higher" plants and by most animals. In vascular plants, for example, the haploid generation is represented by the pollen and the ovule, whilst the diploid generation is the familiar flowering plant.

Life cycle

Most kinds of plants have a double portion of chromosomes in their cells (diploid, i.e. each chromosome exists with a partner that contains the same genetic information) whilst mosses (and other bryophytes) have only a single set of chromosomes (haploid, i.e. each chromosome exists in a unique copy within the cell). There are periods in the moss lifecycle when they do have a full, paired set of chromosomes but this is only during the sporophyte stage. sporophyte The life of a moss starts from a haploid spore, which germinates to produce a protonema, which is either a mass of filaments or thalloid (flat and thallus-like). This is a transitory stage in the life of a moss. From the protonema grows the gametophore ("gamete-bearer") that is differentiated into stems and leaves ('microphylls'). From the tips of stems or branches develop the sex organs of the mosses. The female organs are known as archegonia (singular archegonium) and are protected by a group of modified leaves known as the perichaetum (plural perichaeta). The archegonia have necks called venters which the male sperm swim down. The male organs are known as antheridia (singular antheridium) and are enclosed by modified leaves called the perigonium (plural perigonia). Mosses can be either dioicous (compare with dioecious in seed plants) or monoicous (compare monoecious). In dioicous mosses, both male and female sex organs are borne on different gametophyte plants. In monoicous (also called autoicous) mosses, they are borne on the same plant. In the presence of water, sperm from the antheridia swim to the archegonia and fertilisation occurs, leading to the production of a diploid sporophyte. The sperm of mosses is biflagellate, i.e. they have two flagella that aid in propulsion. Without water, fertilisation cannot occur. After fertilization, the immature sporophyte pushes its way out of the archegonial venter. It takes about a quarter to half a year for the sporophyte to mature. The sporophyte body comprises a long stalk, called a seta, and a capsule capped by a cap called the operculum. The capsule and operculum are in turn sheathed by a haploid calyptra which is the remains of the archegonial venter. The calyptra usually falls off when the capsule is mature. Within the capsule, spore-producing cells undergo meiosis to form haploid spores, upon which the cycle can start again. The mouth of the capsule is usually ringed by a set of teeth called peristome. This may be absent in some mosses. In some mosses, green vegetative structures called gemmae are produced on leaves or branches, which can break off and form new plants without the need to go through the cycle of fertilization. This is a means of asexual reproduction.

Classification of mosses

asexual reproduction asexual reproduction Mosses were traditionally grouped with the liverworts and hornworts in the Division Bryophyta (bryophytes), within which the mosses made up the class Musci. This group, however, is paraphyletic and now tends to be split up. In such system, the Division Bryophyta refers specifically to mosses. They appear to be the closest living relatives of the vascular plants. The mosses are grouped as a single class, now named Bryopsida, and divided into seven subclasses:
- Andreaeidae
- Sphagnidae
- Tetraphidae
- Polytrichidae
- Buxbaumiidae
- Bryidae
- Archidiidae Andreaeidae are distinguished by the biseriate (two rows of cells) rhizoids, multiseriate (many rows of cells) protonema, and sporangium that splits along longitudinal lines. Most mosses have capsules that open at the top. The Sphagnidae, the peat-mosses, comprise the single genus Sphagnum. These form extensive acidic bogs in peat swamps. The leaves of Sphagnum have large dead cells alternating with living photosynthetic cells. The dead cells help to store water. Aside from this character, the unique branching, thallose (flat and expanded) protonema, and explosively rupturing sporangium place it apart from other mosses. The Tetraphidae are unique as their name implies, in having only four large peristome teeth surrounding the opening of the capsule. Polytrichidae have leaves with lamellae, which are flaps on the leaves that look like the fins on a heat sink. These help it retain moisture. They differ from other mosses in other details of their development and anatomy too. The Buxbaumiidae are called 'bug mosses' because they usually have a very small and reduced gametophore and the whole plant is mostly the sporophyte capsule. The shape reminds one of a bug, which is the reason for its common name. Most (>95%) mosses belong to the Bryidae. The Archidiidae are distinguished by their extremely large spores and the way the sporangium develops.

Habitat

Sphagnum Sphagnum Sphagnum Mosses are found chiefly in areas of low light and dampness; any area of the world. Mosses are common in wooded areas and at the edges of streams. A few species are wholly aquatic and otherwes such as mist Sphagnum spp inhabit bogs, marshes and very slow moving water-ways. Mosses are also found in cracks between paving stones in damp city streets. Some types have adapted to urban conditions and are found only in cities. Wherever they occur, mosses require moisture to survive because of the small size and thinness of tissues, lack of cuticle (waxy covering to prevent water loss), and the need for liquid water to complete fertilisation. Some mosses can survive desiccation, returning to life within a few hours of rehydration. In northern latitudes, the north side of trees generally will have more moss on average than other sides. This is assumed to be because of the lack of sufficient water for reproduction on the sun-facing side of trees. South of the equator the reverse is true. In deep forests where sun-light does not penetrate mosses grow equally well on all sides of the tree trunk

Cultivation

Moss is considered a weed in grass lawns, but is deliberately encouraged to grow under aesthetic principles exemplified by Japanese gardening. In old temple gardens, moss can carpet a forest scene. Moss is thought to add a sense of calm, age and stillness to a garden scene. Rules of cultivation are not widely established. Moss collections are quite often begun using samples transplanted from the wild in a water-retaining bag. However, specific species of moss can be extremely difficult to maintain away from their natural site (with its unique combination of light, humidity, shelter from wind, etc). Growing moss from spore is even less controlled. Moss spores fall in a constant rain on exposed surfaces - those surfaces which are hospitable to a certain species of moss will typically be colonized by that moss within a few years of exposure to wind and rain. Materials which are porous and moisture retentive, such as brick, wood, and certain coarse concrete mixtures are hospitable to moss. Surfaces can also be prepared with acidic substances, including buttermilk, yogurt, urine, and gently pureed mixtures of moss samples, water and ericaceous compost.

Mossery

A passing fad for moss collecting in the late 19th Century led to the establishment of mosseries in many British and American gardens. The mossery is typically constructed out of slatted wood, with a flat roof, open to the north side (maintaining shade). Samples of moss were installed in the cracks between wood slats. The whole mossery would then be regularly moistened to maintain growth.

Commercial use of Mosses

There is a substantial market in mosses gathered from the wild. The uses for intact moss are principally in the florist trade and for home decoration. Decaying moss in the genus Sphagnum is also the major component of peat, which is "mined" both as a soil additive and for use in smoking malt in the production of Scotch whiskey. There are growing concerns in parts of the world where this trade is growing that significant environmental damage may be caused by the activities of commercial moss harvesters.

External links

- [http://www.hcs.ohio-state.edu/hcs300/liver2.htm Information, diagrams, and photos]
- [http://149.152.32.5/Plant_Biology/moss.html Moss description] Category: Bryophyta Category: Bryophytes Category: cryptogams ja:蘚類 simple:Mosses

Vascular plant

- Non-seed-bearing plants
- Equisetophyta
- Lycopodiophyta
- Psilotophyta
- Pteridophyta
- Superdivision Spermatophyta
- Pinophyta
- Cycadophyta
- Ginkgophyta
- Gnetophyta
- Magnoliophyta The vascular plants are plants in the Kingdom Plantae (also called Viridiplantae) that have specialized tissues for conducting water. Vascular plants include the ferns, clubmosses, horsetails, flowering plants, conifers and other gymnosperms. Scientific names are Tracheophyta and Tracheobionta, but neither is very widely used. Nonvascular plants include both earlier-derived lineages in Plantae (mosses, hornworts, and liverworts) and members of other kingdoms (the various algae). The vascular plants are set apart in two important ways: # Vascular plants have water-carrying tissues, enabling the plants to evolve to a larger size. Non-vascular plants lack these and are restricted to relatively small sizes. # In vascular plants, the principal generation phase is the sporophyte, which is diploid with two sets of chromosomes per cell. In non-vascular plants, the principal generation phase is often the gametophyte, which is haploid with one set of chromosomes per cell. See also alternation of generations. Water transport happens in either xylem or phloem: xylem carries water and inorganic solutes upward toward the leaves from the roots, while phloem carries organic solutes throughout the plant.

Members

- Spore-bearing vascular plants
- Equisetophyta ~ horsetails
- Lycopodiophyta ~ clubmosses, spikemosses, quillworts
- Psilotophyta ~ whisk-ferns
- Pteridophyta~ ferns
- Seed-bearing vascular plants - Superdivision Spermatophyta
- Pinophyta ~ conifers
- Cycadophyta ~ cycads
- Ginkgophyta ~ ginkgoes
- Gnetophyta ~ gnetophytes
- Magnoliophyta ~ flowering plants

Equisetophyta

- Subgenus Equisetum Equisetum arvense - Field or Common Horsetail
Equisetum bogotense - Andean Horsetail
Equisetum diffusum - Himalayan Horsetail
Equisetum fluviatile - Water Horsetail
Equisetum palustre - Marsh Horsetail
Equisetum pratense - Shade Horsetail
Equisetum sylvaticum - Wood Horsetail
Equisetum telmateia - Great Horsetail
- Subgenus Hippochaete Equisetum giganteum - Giant Horsetail
Equisetum myriochaetum - Mexican Giant Horsetail
Equisetum hyemale - Rough Horsetail
Equisetum laevigatum - Smooth Horsetail
Equisetum ramosissimum - Branched Horsetail
Equisetum scirpoides - Dwarf Horsetail
Equisetum variegatum - Variegated Horsetail The horsetails are vascular plants, comprising 15 species of plants in the genus Equisetum. This genus is the only one in the family Equisetaceae, which in turn is the only family in the order Equisetales and the class Equisetopsida. This class is often placed as the sole member of the Division Equisetophyta (also called Arthrophyta in older works), though some recent molecular analyses place the genus within Pteridophyta, related to Marattiales. The molecular data, however, are somewhat ambiguous as of yet. Other classes and orders of Equisetophyta are known from the fossil record, where they were important members of the world flora during the Carboniferous period. Carboniferous The name horsetail arose because it was thought that the stalk resembled a horse's tail; the name Equisetum is from the Latin equus, "horse", and seta, "bristle". Other names, rarely used, include candock (applied to branching species only), and scouring-rush (applied to the unbranched or sparsely branched species). The name scouring-rush refers to its rush-like appearance and because the stems are coated with abrasive silica that led them to be used for scouring cooking pots in the past. The genus is near-cosmopolitan, being absent only from Australasia and Antarctica. They are perennial plants, either herbaceous, dying back in winter (most temperate species) or evergreen (some tropical species, and the temperate Equisetum hyemale). They mostly grow 0.2-1.5 m tall, though E. telmateia can exceptionally reach 2.5 m, and the tropical American species E. giganteum 5 m, and E. myriochaetum 8 m. In these plants the leaves are greatly reduced, being represented only by whorls of small, translucent scales. The stems are green and photosynthetic, also distinctive in being hollow, jointed, and ridged (with (3-) 6-40 ridges). There may or may not be whorls of branches at the nodes; when present, these branches are identical to the main stem except smaller. The spores are borne in a cone-like structures (strobilus, pl. strobili) at the tip of some of the stems. In many species they are unbranched, and in some (e.g. E. arvense) they are non-photosynthetic, produced early in spring separately from photosynthetic sterile stems. In some other species (e.g. E. palustre) they are very similar to sterile stems, photosynthetic and with whorls of branches. spore Horsetails are mostly homosporous, though in E. arvense, smaller spores give rise to male prothalli. The spores have four elaters that act as moisture-sensitive springs, ejecting the spores through a weak spot of the sporangia. Many plants in this genus prefer sandy soils, though some are aquatic and others adapted to wet clay soils. One horsetail, E. arvense, can be a nuisance weed because it readily regrows after being pulled out. The stalks arise from rhizomes that are deep underground and almost impossible to dig out. It is also unaffected by many herbicides designed to kill seed plants. The foliage is poisonous to grazing animals if eaten in large quantities. The horsetails were a much larger and more diverse group in the distant past before seed plants became dominant across the Earth. Some species were large trees reaching to 30 m tall. The genus Calamites (Family Calamitaceae) is abundant in coal deposits from the Carboniferous period. ---- The superficially similar flowering plant, Mare's tail (Hippuris vulgaris), unrelated to the genus Equisetum, is occasionally misidentified and misnamed as a horsetail.

External links

- [http://www.btinternet.com/~pigott/equisetum/ UK National Collection] - includes a taxonomic list of all known species and hybrids
- [http://members.eunet.at/m.matus/ The Wonderful World of Equisetum]
- [http://www.fiu.edu/~chusb001/giant_equisetum.html Giant horsetails]
- [http://www.floridata.com/ref/e/equi_hye.cfm Equisetum hyemale] Category:Equisetophyta Category: cryptogams ja:トクサ ja:スギナ

Fern

Marattiopsida
Osmundopsida
Gleicheniopsida
Pteridopsida A fern, or pteridophyte, is any one of a group of some twenty thousand species of plants classified in the Division Pteridophyta, formerly known as Filicophyta. A fern is a vascular plant that differs from the more primitive lycophytes in having true leaves (megaphylls) and from the more advanced seed plants (gymnosperms and angiosperms) in lacking seeds. Like all vascular plants, it has a life cycle, often referred to as alternation of generations, characterized by a diploid sporophytic and a haploid gametophytic phase. Unlike the gymnosperms and angiosperms, in ferns the gametophyte is a free-living organism. The life cycle of a typical fern is as follows: # A sporophyte (diploid) phase produces haploid spores by meiosis; # A spore grows by cell division into a gametophyte, which typically consists of a photosynthetic prothallus # The gametophyte produces gametes (often both sperm and eggs on the same prothallus) by mitosis # A mobile, flagellate sperm fertilizes an egg that remains attached to the prothallus # The fertilized egg is now a diploid zygote and grows by mitosis into a sporophyte (the typical "fern" plant).

Fern structure

zygote Like the sporophytes of seed plants, those of ferns consist of:
- Stems: Most often an underground creeping rhizome, but sometimes an above-ground creeping stolon (e.g., Polypodiaceae), or an above-ground erect semi-woody trunk (e.g., Cyatheaceae) reaching up to 20 m in a few species (e.g., Cyathea brownii on Norfolk Island and Cyathea medullaris in New Zealand).
- Leaf: The green, photosynthetic part of the plant. In ferns, it is often referred to as a frond, but this is because of the historical division between people who study ferns and people who study seed plants, rather than because of differences in structure. New leaves typically expand by the unrolling of a tight spiral (the fiddlehead), called circinate vernation. Leaves are further divided into two types:
- Trophophyll: A leaf that does not produce spores, instead only producing sugars by photosynthesis. Analogous to the typical green leaves of seed plants.
- Sporophyll: A leaf that produces spores. These leaves are analogous to the scales of pine cones or to stamens and pistil in gymnosperms and angiosperms, respectively. Unlike the seed plants, however, the sporophylls of ferns are typically not very specialized, looking similar to trophophylls and producing sugars by photosynthesis as the trophophylls do.
- Roots: The underground non-photosynthetic structures that take up water and nutrients from soil. They are always fibrous and are structurally very similar to the roots of seed plants. The gametophytes of ferns, however, are very different from those of seed plants. They typically consist of:
- Prothallus: A green, photosynthetic structure that is one cell thick, usually heart- or kidney-shaped, 3-10 mm long and 2-8 mm broad. The thallus produces gametes by means of:
- Antheridia: Small spherical structures that produce flagellate sperm.
- Archegonia: A flask-shaped structure that produces a single egg at the bottom, reached by the sperm by swimming down the neck.
- Rhizoids: root-like structures that consist of single greatly-elongated cells that take up water and nutrients.

Evolution and classification

Ferns first appear in the fossil record in the early-Carboniferous epoch. By the Triassic, the first evidence of ferns related to several modern families appeared. The "great fern radiation" occurred in the late-Cretaceous, when many modern families of ferns first appeared. Ferns have traditionally been grouped in the Class Filices, but modern classifications assign them their own division in the plant kingdom, called Pteridophyta. Two related groups of plants, commonly known as ferns, are actually more distantly related to the main group of "true" ferns. These are the whisk ferns (Psilophyta) and the adders-tongues, moonworts, and grape-ferns (Ophioglossophyta). The Ophioglossophytes were formerly considered true ferns and grouped in the Family Ophioglossaceae, but were subsequently found to be more distantly related. Some classification systems include the Psilopytes and Ophioglossophytes in Division Pteridophyta, while others assign them to separate divisions. Modern phylogeny indicates that the Ophioglossophytes, Psilopytes, and true ferns together constitute a monophyletic group, descended from a common ancestor. The true ferns may be subdivided into four main groups, or classes (or orders if the true ferns are considered as a class):
- Marattiopsida
- Osmundopsida
- Gleicheniopsida
- Pteridopsida The last group includes most plants familiarly known as ferns. The Marattiopsida are a primitive group of tropical ferns with a large, fleshy rhizome, and are now thought to be a sibling taxon to the main group of ferns, the leptosporangiate ferns, which include the other three groups listed above. Modern research indicates that the Osmundopsida diverged first from the common ancestor of the leptosporangiate ferns, followed by the Gleichenopsida. Pteridopsida Pteridopsida Pteridopsida Pteridopsida A more complete classification scheme follows:
- Division: Pteridophyta
- Class: Marattiopsida
- Order: Marattiales
- Order: Christenseniales
- Class: Osmundopsida
- Order: Osmundales (the flowering ferns)
- Class: Gleicheniopsida
- Subclass: Gleicheniatae
- Order: Gleicheniales (the forked ferns)
- Order: Dipteridales
- Order: Matoniales
- Subclass: Hymenophyllatae
- Order: Hymenophyllales (the filmy ferns)
- Subclass: Hymenophyllopsitae
- Order: Hymenophyllopsidales
- Class: Pteridopsida
- Subclass: Schizaeatae
- Order: Schizeales (including the climbing ferns)
- [heterosporous ferns]
- Order: Marsileales (Hydropteridales) (the water-clovers, mosquito fern, water-spangle)
- Subclass: Cyatheatae
- Order: Cyatheales (the tree ferns)
- Order: Plagiogyriales
- Order: Loxomales
- Subclass: Pteriditae
- Order: Lindseales
- Order: Pteridales (including the brakes and maidenhair ferns)
- Order: Dennstaedtiales (the cup ferns, including bracken)
- Subclass: Polypoditae
- Order: Aspleniales (the spleenworts)
- Order: Athyriales (including the lady ferns, ostrich fern, maiden ferns, etc.)
- Order: Dryopteridales (the wood ferns and sword ferns)
- Order: Davalliales (including the rabbits-foot ferns and Boston ferns)
- Order: Polypodiales (including the rock-cap ferns or Polypodies)

Economic uses

Ferns are not of major economic importance, with one possible exception. Ferns of the genus Azolla, which are very small, floating plants that do not look like ferns, called mosquito fern, are used as a biological fertilizer in the rice paddies of southeast Asia, taking advantage of their ability to fix nitrogen from the air into compounds that can then be used by other plants. Other ferns with some economic significance include:
- Dryopteris filix-mas (male fern), used as a vermifuge
- Rumohra adiantoides (floral fern), extensively used in the florist trade
- Osmunda regalis (royal fern) and Osmunda cinnamomea (cinnamon fern), the root fiber being used horticulturally; the fiddleheads of O. cinnamomea are also used as a cooked vegetable
- Matteuccia struthiopteris (ostrich fern), the fiddleheads used as a cooked vegetable in North America
- Pteridium aquilinum (bracken), the fiddleheads used as a cooked vegetable in Japan
- Diplazium esculentum (vegetable fern), a source of food for some native societies
- Tree ferns, used as building material in some tropical locales In addition, a great many ferns are grown in horticulture.

Misunderstood names

Several non-fern plants are called "ferns" and are sometimes popularly believed to be ferns in error. These include:
- "Asparagus fern" - This may apply to one of several species of the monocot genus Asparagus, which are flowering plants. A better name would be "fern asparagus".
- "Sweetfern" - This is a shrub of the genus Comptonia.
- "Air fern" - This is an unrelated aquatic animal that is related to a coral; it is harvested, dried, dyed green, then sold as plant that can "live on air". It looks like a fern but is actually a skeleton. In addition, the book Where the Red Fern Grows has elicited many questions about the mythical "red fern" named in the book. There is no such known plant, although there has been speculation that the Oblique grape-fern, Sceptridium dissectum, could be referred to here, because it is known to appear on disturbed sites and its fronds may redden over the winter.

External links and sources

- Moran, Robbin C. (2004). A Natural History of Ferns. Portland, OR: Timber Press. ISBN 0-88192-667-1.
- [http://tolweb.org/tree?group=Filicopsida&contgroup=Embryophytes Tree of Life Web Project: Filicopsida]
- A classification of the [http://www.anbg.gov.au/projects/fern/taxa/classification.html ferns and their allies]
- [http://www.jaknouse.athens.oh.us/ferns/bookfern.html A fern book bibliography]
- [http://www1.akira.ne.jp/~unzen/pteridophyta.html Register of fossil Pteridophyta]
- [http://delta-intkey.com/britfe/ L. Watson and M.J. Dallwitz (2004 onwards). The Ferns (Filicopsida) of the British Isles.] http://delta-intkey.com Category:Pteridophyta ja:シダ植物門

Whisk fern

- Psilotum nudum (L.) Beauvois
- Psilotum complanatum Sw. Psilotum (whisk ferns) is a genus of fern-like vascular plants, the sole genus in the family Psilotaceae and the order Psilotales. They have traditionally been thought not to be true ferns, but rather, odd "primitive" vascular plants that reproduce solely by spores, without seeds. Recent evidence has however suggested that they may in fact be ferns that have lost a number of pteridophytic characteristics, but their status is still uncertain. There are two species, Psilotum nudum and Psilotum complanatum, with a hybrid between them known, Psilotum x intermedium W. H. Wagner. The distribution of Psilotum is tropical and subtropical, in the New World, Asia, and the Pacific. The highest latitudes known are in South Carolina and southern Japan for P. nudum. Category:Plants ms:Paku-pakis whisk

Spermatophyta

The spermatophytes (also known as phanerogams) comprise those plants that produce seeds. They are included in the embryophytes or land plants, which also includes various groups that reproduce by spores, such as mosses, liverworts, hornworts, and ferns. Seed-bearing plants were traditionally divided into angiosperms, or flowering plants, and gymnosperms, which includes the gnetae, cycads, ginkgo, and conifers. Angiosperms are now thought to have evolved from a gymnosperm ancestor, which would make the gymnosperm taxon paraphyletic. Modern cladistics attempts to define taxa that are monophyletic, traceable to a common ancestor and inclusive therefore of all descendants of that common ancestor. Although not a monophyletic taxon, gymnosperm is still widely used to distinguish the four taxa of non-flowering, seed-bearing plants from the angiosperms. A traditional classification grouped all the seed plants together as follows:
- Division Spermatophyta
- Cycadopsida, the cycads
- Ginkgoopsida, the ginkgo
- Pinopsida, the conifers, ("Coniferopsida")
- Gnetopsida, including Gnetum, Welwitschia, Ephedra
- Magnoliopsida, the flowering plants, or Angiospermopsida In addition to the taxa listed above, the fossil record contains evidence of many extinct taxa of seed plants. The so-called "seed ferns" (Pteridospermae) were one of the earliest successful groups of land plants, and forests dominated by seed ferns were prevalent in the late Paleozoic. Glossopteris was the most prominent tree genus in the ancient southern supercontinent of Gondwana during the Permian period. By the Triassic period, seed ferns had declined in importance, and gymnosperms were predominant until the Cretaceous, when the Angiosperms became predominant. Cretaceous A more modern classification splits these groups into separate divisions (sometimes under the Superdivision Spermatophyta):
- Cycadophyta, the cycads
- Ginkgophyta, the ginkgo
- Pinophyta, the conifers
- Gnetophyta, including Gnetum, Welwitschia, Ephedra
- Magnoliophyta, the flowering plants sort30 Spermatophyta ko:종자식물 ja:種子植物

Pinophyta

Cordaitales †
Pinales
  Pinaceae - Pine family
  Araucariaceae - Araucaria family
  Podocarpaceae - Yellow-wood family
  Sciadopityaceae - Umbrella-pine family
  Cupressaceae - Cypress family
  Cephalotaxaceae - Plum-yew family
  Taxaceae - Yew family
Vojnovskyales †
Voltziales † The conifers, division Pinophyta, are one of 13 or 14 division level taxa within the Kingdom Plantae. They are cone-bearing seed plants with vascular tissue; all extant conifers are woody plants, the great majority being trees with just a few being shrubs. Typical examples of conifers include cedars, cypresses, douglas-firs, firs, junipers, kauris, larches, pines, redwoods, spruces, and yews. Species of conifers can be found growing naturally in almost all parts of the world, and are frequently dominant plants in their habitats, as in e.g. the taiga. Conifers are of immense economic value, primarily for timber and paper production; the wood of conifers is known as softwood.

Taxonomy and naming

The division name Pinophyta conforms with the rules of the ICBN, which state (Art 16.1) that the names of higher taxa in plants (above the rank of family) are either based on the name of the type genus, in this case, Pinus (pines), or are descriptive. In the latter case the name for the conifers is Coniferae (Art 16 Ex 2), which is in widespread use as well. Older scientific names (no longer allowed) are Coniferophyta and Coniferales. In an older, broader sense of the name, the conifers were often considered equivalent to the Gymnosperms, although this grouping is polyphyletic as it includes distinct, only distantly related plants like the cycads and ginkgos not in the Pinophyta, but excludes the Magnoliophyta (flowering plants), equally or perhaps more closely related. The division contains just one class of living plants, class Pinopsida. Subdivision of the conifers into two or more orders has been proposed from time to time. The most commonly seen in the past was a split into two orders, Taxales (Taxaceae only) and Pinales (the rest), but recent genetic evidence has shown that this interpretation leaves the Pinales without Taxales as polyphyletic, and the latter order is no longer regarded as distinct. A more accurate division would be to split the division into three orders, Pinales containing only Pinaceae, Araucariales containing Araucariaceae and Podocarpaceae, and Cupressales (including Taxales) containing the remaining families, but there has not been any significant support for any division, with the majority of opinion preferring retention of all the families within a single order Pinales, despite their antiquity and diverse morphology. polyphyletic The conifers are now accepted as comprising six to eight families, with a total of 65-70 genera and 600-650 species. The seven most distinct families are linked in the box above right and phylogenetic diagram left. In other interpretations, the Cephalotaxaceae may be better included within the Taxaceae, and some authors additionally recognise Phyllocladaceae as distinct from Podocarpaceae (in which it is included here). A further family Taxodiaceae was widely recognised in the past, but is now normally included within Cupressaceae. The conifers are an ancient group, with a fossil record extending back about 300 million years to the Paleozoic in the late Carboniferous period; even many of the modern genera are recognisable from fossils 60-120 million years old. Other classes and orders, now long extinct, also occur as fossils, particularly from the late Paleozoic and Mesozoic eras. Fossil conifers included many diverse forms, the most dramatically distinct from modern conifers being some herbaceous conifers with no woody stems. Major fossil orders of conifers or conifer-like plants include the Cordaitales, Vojnovskyales, Voltziales and perhaps also the Czekanowskiales (possibly more closely related to the Ginkgophyta).

Morphology

All living conifers are woody plants, and most are trees, the majority having monopodial growth form (a single, straight trunk with side branches). The size of mature conifers varies from less than one metre, to over 100 metres. The world's tallest, largest, thickest and oldest living things are all conifers. The tallest is a Coast Redwood (Sequoia sempervirens), with a height of 112.34 metres. The largest is a Giant Sequoia (Sequoiadendron giganteum), with a volume 1486.9 cubic metres. The thickest, or tree with the greatest trunk diameter, is a Montezuma Cypress (Taxodium mucronatum), 11.42 metres in diameter. The oldest is a Great Basin Bristlecone Pine (Pinus longaeva), 4,700 years old.

Foliage

Great Basin Bristlecone Pine (Pseudotsuga menziesii)]] Great Basin Bristlecone Pine (Chamaecyparis lawsoniana); scale in mm]] The leaves of many conifers are long, thin and needle-like, but others, including most of the Cupressaceae and some of the Podocarpaceae, have flat, triangular scale-like leaves. Some, notably Agathis in Araucariaceae and Nageia in Podocarpaceae, have broad, flat strap-shaped leaves. In the majority of conifers, the leaves are arranged spirally, exceptions being most of Cupressaceae and one genus in Podocarpaceae, where they are arranged in decussate opposite pairs or whorls of 3 (-4). In many species with spirally arranged leaves, the leaf bases are twisted to present the leaves in a flat plane for maximum light capture (see e.g. photo of Grand Fir Abies grandis). Leaf size varies from 2 mm in many scale-leaved species, up to 400 mm long in the needles of some pines (e.g. Apache Pine Pinus engelmannii). The stomata are in lines or patches on the leaves, and can be closed when it is very dry or cold. The leaves are often dark green in colour which may help absorb a maximum of energy from weak sunshine at high latitudes or under forest canopy shade. Conifers from hotter areas with high sunlight levels (e.g. Turkish Pine Pinus brutia) often have yellower-green leaves, while others (e.g. Blue Spruce Picea pungens) have a very strong glaucous wax bloom to reflect ultraviolet light. In the great majority of genera the leaves are evergreen, usually remaining on the plant for several (2-40) years before falling, but three genera (Larix, Taxodium and Metasequoia) are deciduous, shedding the leaves in autumn and leafless through the winter. The seedlings of many conifers, including most of the Cupressaceae, and Pinus in Pinaceae, have a distinct juvenile foliage period where the leaves are different, often markedly so, from the typical adult leaves.

Reproduction

deciduous See conifer cones for a more detailed discussion. Most conifers are monoecious, but some are subdioecious or dioecious; all are wind-pollinated. Conifer seeds develop inside a protective cone called a strobilus (or, very loosely, "pine cones", which technically occur only on pines, not other conifers!). The cones take from four months to three years to reach maturity, and vary in size from 2 mm to 600 mm long. In Pinaceae, Araucariaceae, Sciadopityaceae and most Cupressaceae, the cones are woody, and when mature the scales usually spread open allowing the seeds to fall out and be dispersed by the wind. In some (e.g. firs), the cones disintegrate to release the seeds, and in others (e.g. the pines that produce pine nuts) the nut-like seeds are dispersed by birds (mainly nutcrackers and jays) which break up the specially adapted softer cones. Ripe cones may remain on the plant for a varied amount of time before falling to the ground; in some fire-adapted pines, the seeds may be stored in closed cones for up to 60-80 years, being released only when a fire kills the parent tree. jay In the families Podocarpaceae, Cephalotaxaceae, Taxaceae, and one Cupressaceae genus (Juniperus), the scales are soft, fleshy, sweet and brightly coloured, and are eaten by fruit-eating birds, which then pass the seeds in their droppings. These fleshy scales are (except in Juniperus) known as arils. In some of these conifers (e.g. most Podocarpaceae), the cone consists of several fused scales, while in others (e.g. Taxaceae), the cone is reduced to just one seed scale or (e.g. Cephalotaxaceae) the several scales of a cone develop into individual arils, giving the appearance of a cluster of berries. The male cones have structures called microsporangia which produce yellowish pollen. Pollen is released and carried by the wind to female cones. Pollen grains from living pinophyte species produce pollen tubes, much like those of angiosperms. When a pollen grain lands near a female gametophyte, it undergoes meiosis and fertilizes the female gametophyte. The resulting zygote develops into an embryo, which along with its surrounding integument, becomes a seed. Eventually the seed may fall to the ground and, if conditions permit, grows into a new plant. In forestry, the terminology of flowering plants has commonly though inaccurately been applied to cone-bearing trees as well. The male cone and unfertilized female cone are called "male flower" and "female flower", respectively. After fertilization, the female cone is term "fruit", which undergoes "ripening" (maturation).

Life cycle

# To fertilize the ovum, the male cone releases pollen that is carried on the wind to the female cone. # A fertilized female gamete (called a zygote) develops into an embryo. # Along with integument cells surrounding the embryo, a seed develops containing the embryo. # Mature seed drops out of cone onto the ground. # Seed germinates and seedling grows into a mature plant. # When mature, the adult plant produces cones.

Other facts

seed Although the total number of species is relatively small, conifers are of immense ecological importance. They are the dominant plants over huge areas of land, most notably the boreal forests of the northern hemisphere, but also in similar cool climates in mountains further south. Many conifers have distinctly scented resin, secreted to protect the tree against insect infestation and fungal infection of wounds. Fossilised resin hardens into amber.

External link

- [http://tolweb.org/tree?group=Conifers&contgroup=Spermatopsida ToLweb: Conifers] Category:Conifers ko:구과식물 ja:球果植物門

Ginkgo

The Ginkgo (Ginkgo biloba), sometimes also known as the Maidenhair Tree, is a unique tree with no close living relatives. It is classified in its own division, the Ginkgophyta, comprising the single class Ginkgoopsida, order Ginkgoales, family Ginkgoaceae, genus Ginkgo and just the one species. It is one of the best examples of a living fossil known. In the past it has also been placed in the divisions Spermatophyta or Pinophyta. Ginkgo is a gymnosperm (as opposed to an angiosperm), meaning "naked seed"; its seeds are not protected by a fruit. For centuries it was thought to be extinct in the wild, but is now known to grow wild in at least two small areas in Zhejiang province in eastern China, in the Tian Mu Shan Reserve. However, as this area has known human activity for over a thousand years, the wild status of ginkgos there is as of yet uncertain.

Characteristics

China

Habit

Ginkgos are medium-large deciduous trees, reaching 20-35 m tall (some specimens in China being over 50 m), with an often angular crown and long, somewhat erratic branches. They are usually deep rooted and resistant to wind and snow damage. Young trees are often tall and slender, and sparsely branched; the crown becomes broader as the tree ages. During autumn, the leaves turn a bright yellow, then fall, sometimes within a short space of time (1-15 days). A combination of amazing disease resistance, insect-resistant wood and the ability to form aerial roots and sprouts means that ginkgos are very long-lived, with some specimens claimed to be more than 2,500 years old. Some old Ginkgos produce aerial roots, known as chichi (Japanese; "nipples") or zhong-ru (Chinese), which form on the undersides of large branches and grow downwards. Chichi growth is very slow, and may take hundreds of years to occur. The function, if any, of these thick aerial roots is unknown.

Stem

Ginkgo branches grow in length by apical growth of "long shoots", i.e. ordinary shoots with regularly spaced leaves, as on most trees. These have elongated internodes, and their leaves are often bilobed. From the axils of these leaves, "spur shoots" (also known as short shoots) develop on second-year growth. They have very short internodes (so that several years' growth may extend a spur shoot by only a centimetre or two) and their leaves are ordinarily unlobed. Reproductive structures are only formed from the spur shoots (see picture to above left). In Ginkgos, as in other plants that possess them, spur shoots allow the formation of new leaves in the older parts of the crown. After a number of years, a spur shoot may change into a long shoot, and vice versa.

Leaf

The leaves are unique among seed plants, being fan-shaped with veins radiating out into the leaf blade, sometimes bifurcating but never anastomosing to form a network. Two veins enter the leaf blade at the base and fork repeatedy in two; this is known as dichotomous venation. The leaves are 5-10 cm (rarely to 15 cm) long. The old popular name "Maidenhair tree" is because the leaves resemble some of the pinnae of the Maidenhair fern Adiantum capillus-veneris. Leaves of long shoots are usually notched or lobed, but only from the outer surface, between the veins. The leaves are borne both on the more rapidly-growing branch tips, where they are alternate and spaced out, and also on the short, stubby spur shoots, where they are clustered at the tips.

Reproduction

Maidenhair fern Ginkgos are dioecious, with separate sexes, some trees being female and others being male. Male plants produce small pollen cones with sporophylls each bearing two microsporangia spirally arranged around a central axis. Female plants do not produce cones. Two ovules are formed at the end of a stalk, and after pollination, one or both develop into seeds. The seed is 1.5-2 cm long. Its outer layer (the sarcotesta) is light yellow-brown, soft, and fruit-like. It is plum-like and attractive, but contains butanoic acid and thus smells like rancid butter (which contains the same chemical). Beneath the sarcotesta is the hard sclerotesta and a papery endotesta and nucellus.

Name

The name Ginkgo means "silver apricot" (銀杏 yín xìng) in Chinese. The same name was used in Japan (where Ginkgo had been introduced from China) in the 17th century, but the Japanese pronunciation was ginkyō. This was the name encountered by Engelbert Kaempfer, the first Westerner to see the species, in 1690. The modern Japanese reading is ichō or ginnan (although the kanji text is the same). The modern Chinese name for its shelled seeds is 白果 (bái guǒ), meaning "white fruit".

Prehistory

kanji The Ginkgo is a living fossil, with fossils recognisably related to modern Ginkgo from the Permian, dating back 270 million years. They diversified and spread throughout Laurasia during the middle Jurassic and Cretaceous, but became much rarer thereafter. By the Paleocene, Ginkgo adiantoides was the only Ginkgo species left in the Northern Hemisphere (but see below) with a markedly different (but not well-documented) form persisting in the Southern Hemisphere, and at the end of the Pliocene ginkgo fossils disappeared from fossil record everywhere apart from a small area of central China where the modern species survived. It is in fact doubtful whether the Northern Hemisphere fossil species of Ginkgo can be reliably distinguished; given the slow pace of evolution in the genus, there may have been only 2 in total: what is today called G. biloba (including G. adiantoides) and G. gardneri from the Paleocene of Scotland. At least morphologically, G. gardneri and the Southern Hemisphere species are the only known post-Jurassic taxa that can be unequivocally recognised, the remainder may just as well have simply been ecotypes or subspecies. The implications would be that G. biloba had occurred over an extremely wide range, had remarkable genetic flexibility and though evolving genetically never showed much speciation. The occurrence of G. gardneri, it seems a Caledonian mountain endemic, and the somewhat greater diversity on the Southern Hemisphere, suggests that old mountain ranges on the Northern Hemisphere could hold other, presently undiscovered, fossil Ginkgo species. Since the distribution of Ginkgo was already relictual in late prehistoric times, the chances that ancient DNA from subfossils can shed any light on this problem seem remote. While it may seem improbable that a species may exist as a contiguous entity for many millions of years, many of the Ginkgo's life-history parameters fit, notably extreme longevity, slow reproduction rate, and (in Cenozoic and later times) a wide, apparently contiguous, but steadily contracting distribution coupled with, as far as can be demonstrated from the fossil record, extreme ecological conservatism (being restricted to light soils around rivers) and a low population density. Ginkgophyta fossils have been classified in the following families and genera:
- Ginkgoaceae
- Arctobaiera
- Baiera
- Eretmophyllum
- Ginkgo
- Ginkgoites
- Sphenobaiera
- Windwardia
- Trichopityaceae
- Trichopitys Ginkgo has been used for classifying plants with leaves that have more than four veins per segment, while Baiera for those with less than four veins per segment. Sphenobaiera has been used to classify plants with a broadly wedge-shaped leaf that lacks a distinct leaf stem. Trichopitys is distinguished by having multiple-forked leaves with cylindrical (not flattened) thread-like ultimate divisions; it is one of the earliest fossils ascribed to the Ginkgophyta.

Cultivation and uses

Ginkgo has long been cultivated in China; some planted trees at temples are believed to be over 1,500 years old. The first record of Europeans encountering it is in 1690 in Japanese temple gardens, where the tree was seen by the Dutch botanist Engelbert Kaempfer. Because of its status in Buddhism and Confucianism, the Ginkgo is also widely planted in Korea and parts of Japan; in both areas, some naturalisation has occurred, with Ginkgos seeding into natural forests. The seed is edible after removing the ovary pulp, shelling, and after being cooked. Usually only a few are added for a portion enough for ten people. An overdose of the fruit could cause poisoning because the fruit produces hydrogen cyanide as a side product. It is reported that a dozen raw ginkgo fruits are toxic enough to kill a small child, though this has yet to be proven. Some people are sensitive to the chemicals in the sarcotesta. These people should handle the seeds with care when removing the sarcotesta, wearing disposable gloves. The symptoms are a rash or blisters similar to that from poison-ivy. In some areas, notably the United States, most intentionally-planted Ginkgos are male cultivars grafted onto plants propagated from seed, because the male trees will not produce the malodorous fruits (although the seeds within are quite tasty, and a delicacy in Asia). The popular cultivar 'Autumn Gold' is a clone of a male plant. However, the nuts are esteemed in and outside of Asia, and are a traditional Chinese food (e.g. congee, often served at weddings), and are believed to have health benefits; some also consider them to have aphrodisiac qualities. Japanese cooks add Ginkgo seeds to dishes such as chawammushi, and cooked seeds are often eaten along with other dishes. chawammushi The Ginkgo has the intriguing distinction of being one of the world's most urban-tolerant trees, often growing where other trees cannot survive. Some claim that only one tree species, the Tree-of-heaven, is more urban-tolerant. Ginkgos rarely suffer disease problems, even in urban conditions, and are attacked by few insects. For this reason, and for their general beauty, ginkgos are excellent urban and shade trees, and are widely planted along many streets. The trees are easy to propagate from seed. Ginkgos are also popular subjects for growing as penjing and bonsai; they can be kept artificially small and tended over centuries. Extreme examples of the Ginkgo's tenacity may be seen in Hiroshima, Japan, where four trees growing between 1-2 km from the 1945 atom bomb explosion were among the few living things in the area to survive the blast ([http://www.xs4all.nl/~kwanten/hiroshima.htm photos & details]).

Medical uses

The extract of the Ginkgo leaves contains flavonoid glycosides and ginkgolides and has been used pharmaceutically. It has many alleged properties, but is mainly used as memory enhancer and anti-vertigo agent. However, studies differ about its efficacy. It is commonly added to energy drinks, but it is expensive, so the amount is typically so low it does not produce a noticeable effect, except for the placebo effect from being listed on the label.

Side effects

Ginkgo may have some undesirable effects, especially for individuals with blood circulation disorders and those taking anti-coagulants such as aspirin. It should also not be used by people who are taking the anti-depressant drugs known as monoamine oxidase inhibitors (MAOI) or by pregnant women. Ginkgo side effects and cautions include increased risk of bleeding, gastrointestinal discomfort, nausea, vomiting, diarrhea, headaches, and restlessness. Ginkgo should also not be used by pregnant women or people with a blood clotting disorder. If any side effects are experienced the dosage should be lowered immediately. Ginkgo supplements are usually taken in the range of 40-200 mg per day. If the side effects continue usage should be stopped completely.

External links

- [http://www.xs4all.nl/~kwanten The Ginkgo Pages]: all aspects, in English, German, French, Spanish and Dutch
- [http://www.conifers.org/gi/gi/index.htm Gymnosperm Database]
- [http://www.ucmp.berkeley.edu/seedplants/ginkgoales/ginkgo.html Info] by the University of California Museum of Paleontology
- [http://www.phytochemicals.info/ginkgo.php Phytochemicals in ginkgo]
- [http://www.Planet-Weimar.de The Ginkgo Museum], Weimar, Germany
- [http://www.ottawahort.org/ginkgo.htm Growing Ginkgoes from seed]: by the Ottawa Horticultural Society Category:Gymnosperms Category:Living fossils Category:Japanese terms Category:Herbal & fungal drugs/medicines __notoc__ ko:은행나무 ja:イチョウ

Gnetae

- Gnetales
- Welwitschiales
- Ephedrales The plant division Gnetophyta or gnetophytes comprise three related families of woody plants grouped in the gymnosperms, a paraphyletic group of seed plant divisions. The gnetophytes differ from other gymnosperms in having wood vessels as in the flowering plants (Angiosperms or Magnoliophytes), and it is thought that Gnetophytes may be the group of spermatophytes most closely related to the flowering plants. The Gnetophytes are divided into three orders, each containing a single family and genus:
- Gnetales: Gnetaceae; Gnetum
- Welwitschiales: Welwitschiaceae; Welwitschia
- Ephedrales: Ephedraceae; Ephedra The Gnetales consist of a single genus, Gnetum, which are mostly woody climbers in tropical forests. However, the most well-known member of this group, Gnetum gnemon, is a tree. The seeds produced are used to produce a crispy snack known as 'Keropok Belinjau' in Malaysia and Indonesia. The Malay name for this plant is 'belinjau'. The Welwitschiales comprise only one species, Welwitschia mirabilis. It grows only in the deserts of Namibia. The plant is strange in having only two large strap-like leaves for all its life. These grow continuously from the base, and are usually tattered at the ends by flapping in the winds. The Ephedrales consist of a single genus Ephedra, and are known as the jointfirs because they have long slender branches which bear tiny scale-like leaves at their nodes. Ephedra is reputed to have medicinal properties, but has recently been banned by the FDA due to harmful and potentially deadly side effects. Category:Gnetophyta

Plant

- Land plants (embryophytes)
- Non-vascular plants (bryophytes)
- Marchantiophyta - liverworts
- Anthocerotophyta - hornworts
- Bryophyta - mosses
- Vascular plants (tracheophytes)
- Lycopodiophyta - clubmosses
- Equisetophyta - horsetails
- Pteridophyta - "true" ferns
- Psilotophyta - whisk ferns
- Ophioglossophyta - adderstongues
- Seed plants (spermatophytes)
- †Pteridospermatophyta - seed ferns
- Pinophyta - conifers
- Cycadophyta - cycads
- Ginkgophyta - ginkgo
- Gnetophyta - gnetae
- Magnoliophyta - flowering plants Magnoliophyta Plants are a major group of living things (about 300,000 species), including familiar organisms such as trees, flowers, herbs, and ferns. Aristotle divided all living things between plants, which generally do not move or have sensory organs, and animals. In Linnaeus' system, these became the Kingdoms Vegetabilia (later Plantae) and Animalia. Since then, it has become clear that the Plantae as originally defined included several unrelated groups, and the fungi and several groups of algae were removed to new kingdoms. However, these are still often considered plants in many contexts. Indeed, any attempt to match "plant" with a single taxon is doomed to fail, because plant is a vaguely defined concept unrelated to the presumed phylogenic concepts on which modern taxonomy is based.

Embryophytes

:See main article at Embryophytes Most familiar are the multicellular land plants, called embryophytes. They include the vascular plants, plants with full systems of leaves, stems, and roots. They also include a few of their close relatives, often called bryophytes, of which mosses and liverworts are the most common. All of these plants have eukaryotic cells with cell walls composed of cellulose, and most obtain their energy through photosynthesis, using light and carbon dioxide to synthesize food. About three hundred plant species do not photosynthesize but are parasites on other species of photosynthetic plants. Plants are distinguished from green algae, from which they evolved, by having specialized reproductive organs protected by non-reproductive tissues. Bryophytes first appeared during the early Palaeozoic. They can only survive where moisture is available for significant periods, although some species are desiccation tolerant. Most species of bryophyte remain small throughout their life-cycle. This involves an alternation between two generations: a haploid stage, called the gametophyte, and a diploid stage, called the sporophyte. The sporophyte is short-lived and remains dependent on its parent gametophyte. Vascular plants first appeared during the Silurian period, and by the Devonian had diversified and spread into many different land environments. They have a number of adaptations that allowed them to overcome the limitations of the bryophytes. These include a cuticle resistant to desiccation, and vascular tissues which transport water throughout the organism. In most the sporophyte acts as a separate individual, while the gametophyte remains small. Devonians (Pteridophyta) more closely allied to seed plants than they are to clubmosses (Lycopodiophyta)]] The first primitive seed plants, Pteridosperms (seed ferns) and Cordaites, both groups now extinct, appeared in the late Devonian and diversified through the Carboniferous, with further evolution through the Permian and Triassic periods. In these the gametophyte stage is completely reduced, and the sporophyte begins life inside an enclosure called a seed, which develops while on the parent plant, and with fertilisation by means of pollen grains. Whereas other vascular plants, such as ferns, reproduce by means of spores and so need moisture to develop, some seed plants can survive and reproduce in extremely arid conditions. Early seed plants are referred to as gymnosperms (naked seeds), as the seed embryo is not enclosed in a protective structure at pollination, with the pollen landing directly on the embryo. Four surviving groups remain widespread now, particularly the conifers, which are dominant trees in several biomes. The angiosperms, comprising the flowering plants, were the last major group of plants to appear, emerging from within the gymnosperms during the Jurassic and diversifying rapidly during the Cretaceous. These differ in that the seed embryo is enclosed, so the pollen has to grow a tube to penetrate the protective seed coat; they are the predominant group of flora in most biomes today.

Algae and Fungi

The algae comprise several different groups of organisms that produce energy through photosynthesis. However, they are not classified within the kingdom plantae but in the kingdom protista instead. The most conspicuous are the seaweeds, multicellular algae that often closely resemble terrestrial plants, but as stated above are not plants, found among the green, red, and brown algae. These and other algal groups also include various single-celled creatures and forms that are simple collections of cells, without differentiated tissues. Many can move about, and some have even lost their ability to photosynthesize; when first discovered, these were considered as both plants and animals. Now they are considered neither, but protists. The embryophytes developed from green algae; the two are collectively referred to as the green plants or Viridiplantae. The kingdom Plantae is now usually taken to mean this monophyletic group, as shown above. With a few except