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Gnetophyta
 
 
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The plant
Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
 division Gnetophyta or gnetophytes comprise three related families of woody plant
Woody plant

A woody plant is a Vascular tissue plant that has a Perennial plant Plant stem that is above ground and covered by a layer of thickened bark. Woody plants are adapted to survive from one year to the next; the stem supports continued vegetative growth above ground from one year to next....
s grouped in the gymnosperm
Gymnosperm

Gymnosperm is a group of spermatophyte seed-bearing plants with ovules on scales, which are usually arranged in cone-like structures. The other major group of seed-bearing plants, the angiosperms, [from the Greek, 'angion' - container] have ovules enclosed in a carpel, a sporophyll with fused margins....
s. The gnetophytes differ from other gymnosperms in having vessel element
Vessel element

A vessel element is one of the cell types found in xylem, the water conducting tissue of plants. Vessel elements are typically found in the angiosperms but absent from most gymnosperms such as the conifers....
s as in the flowering plant
Flowering plant

The flowering plants or angiosperms are the most widespread group of Embryophytes. The flowering plants and the gymnosperms are the only extant groups of Spermatophyte....
s (Angiosperms or Magnoliophytes).

The living Gnetophyta comprise three genera:

Gnetum
Gnetum

Gnetum is a genus of about 30-35 species of gymnosperms, the sole genus in the family Gnetaceae and order Gnetales. They are tropical evergreen trees, shrubs and lianas....
 species are mostly wood
Wood

Wood is an organic material; in the strict sense wood is produced as secondary xylem in the stems of woody plants, notably trees but also shrubs, etc....
y climbers
Vine

A vine is any plant of genus Grape or, by extension, any similar climbing or trailing plant. The word, derived from Latin vinea, referred to the grape-bearing variety....
 in tropical forests. However, the most well-known member of this group, Gnetum gnemon
Gnetum gnemon

Gnetum gnemon is a species of Gnetum native to southeast Asia and the western Pacific Ocean islands, from Assam south and east through Indonesia and Malaysia to the Philippines and Fiji....
, is a tree.






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The plant
Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
 division Gnetophyta or gnetophytes comprise three related families of woody plant
Woody plant

A woody plant is a Vascular tissue plant that has a Perennial plant Plant stem that is above ground and covered by a layer of thickened bark. Woody plants are adapted to survive from one year to the next; the stem supports continued vegetative growth above ground from one year to next....
s grouped in the gymnosperm
Gymnosperm

Gymnosperm is a group of spermatophyte seed-bearing plants with ovules on scales, which are usually arranged in cone-like structures. The other major group of seed-bearing plants, the angiosperms, [from the Greek, 'angion' - container] have ovules enclosed in a carpel, a sporophyll with fused margins....
s. The gnetophytes differ from other gymnosperms in having vessel element
Vessel element

A vessel element is one of the cell types found in xylem, the water conducting tissue of plants. Vessel elements are typically found in the angiosperms but absent from most gymnosperms such as the conifers....
s as in the flowering plant
Flowering plant

The flowering plants or angiosperms are the most widespread group of Embryophytes. The flowering plants and the gymnosperms are the only extant groups of Spermatophyte....
s (Angiosperms or Magnoliophytes).

The living Gnetophyta comprise three genera:
  • Gnetum
    Gnetum

    Gnetum is a genus of about 30-35 species of gymnosperms, the sole genus in the family Gnetaceae and order Gnetales. They are tropical evergreen trees, shrubs and lianas....
  • Welwitschia
    Welwitschia

    Welwitschia is a monotypic genus of gymnosperm plant, composed solely of the very distinct Welwitschia mirabilis. It is the only genus of the family Welwitschiaceae, in the order Welwitschiales, in the division Gnetophyta....
  • Ephedra
    Ephedra (genus)

    Ephedra is a genus of gymnosperm shrubs, the only genus in the family Ephedraceae and order Ephedrales. These plants occur in dry climates over a wide area mainly in the northern hemisphere, across southern Europe, north Africa, southwest and central Asia, southwestern North America, and, in the southern hemisphere, in South A...


Gnetum
Gnetum

Gnetum is a genus of about 30-35 species of gymnosperms, the sole genus in the family Gnetaceae and order Gnetales. They are tropical evergreen trees, shrubs and lianas....
 species are mostly wood
Wood

Wood is an organic material; in the strict sense wood is produced as secondary xylem in the stems of woody plants, notably trees but also shrubs, etc....
y climbers
Vine

A vine is any plant of genus Grape or, by extension, any similar climbing or trailing plant. The word, derived from Latin vinea, referred to the grape-bearing variety....
 in tropical forests. However, the most well-known member of this group, Gnetum gnemon
Gnetum gnemon

Gnetum gnemon is a species of Gnetum native to southeast Asia and the western Pacific Ocean islands, from Assam south and east through Indonesia and Malaysia to the Philippines and Fiji....
, is a tree. Its seeds are used to produce a crispy krupuk snack known as emping or krupuk belinjo.

Welwitschia
Welwitschia

Welwitschia is a monotypic genus of gymnosperm plant, composed solely of the very distinct Welwitschia mirabilis. It is the only genus of the family Welwitschiaceae, in the order Welwitschiales, in the division Gnetophyta....
 comprises only one species, Welwitschia mirabilis. It grows only in the deserts of Namibia
Namibia

Namibia, officially the Republic of Namibia, is a country in southern Africa on the Atlantic Ocean coast. It shares borders with Angola and Zambia to the north, Botswana to the east, and South Africa to the south....
 and Angola
Angola

Angola, officially the Republic of Angola , is a country in south-central Africa bordering Namibia to the south, Democratic Republic of the Congo to the north, and Zambia to the east, and with a west coast along the Atlantic Ocean....
. 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.

Plants of the genus Ephedra
Ephedra (genus)

Ephedra is a genus of gymnosperm shrubs, the only genus in the family Ephedraceae and order Ephedrales. These plants occur in dry climates over a wide area mainly in the northern hemisphere, across southern Europe, north Africa, southwest and central Asia, southwestern North America, and, in the southern hemisphere, in South A...
 are known as jointfirs because they have long slender branches which bear tiny scale-like leaves at their nodes. Ephedra has been traditionally used as a stimulant
Stimulant

Stimulant drugs are drugs that temporarily increase alertness and awareness. They usually have increased side-effects with increased effectiveness, and the more powerful variants are therefore often prescription medicines or illegal drugs....
, but is a controlled substance today in many jurisdictions because of the risk of harmful or even fatal overdosing.

In some classifications all three genera are placed in a single order (Gnetales) but in others distributed among three orders, each containing a single family and genus.

Gnetum and Welwitschia diverged from each other more recently than from Ephedra.

Knowledge of fossils of the gnetophytes has increased greatly since the 1980s. There are fossils from the Permian
Permian

The PermianThe term "Permian" was introduced into geology in 1841 by Sir Roderick Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian system" after the ancient kingdom...
, the Triassic
Triassic

The Triassic is a geologic period that extends from about 251 to 199 annum . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic....
, and the Jurassic
Jurassic

The Jurassic is a geologic period that extends from about annum to  Ma, that is, from the end of the Triassic to the beginning of the Cretaceous....
 which may belong to the gnetophytes, but this is uncertain. The fossil record is richer starting in the early Cretaceous
Cretaceous

The Cretaceous , usually abbreviated K for its German translation Kreide, is a geologic period from circa to million years ago . In the geologic timescale, the Cretaceous follows on the Jurassic period and is followed by the Paleogene period....
, with fossils of plants as well as seed
Seed

A seed is a small Plant embryogenesis plant enclosed in a covering called the seed coat, usually with some Food storage. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant....
s and pollen
Pollen

Pollen is a fine to coarse powder consisting of Gametophyte , which produce the male gametes of spermatophyta. A hard coat covering the pollen grain protects the sperm cells during the process of their movement between the stamens of the flower to the pistil of the next flower....
 which can be clearly assigned to the gnetophytes.

Molecular phylogenies of extant gymnosperms have conflicted with morphological characters with regard to whether the gymnosperms as a whole (including gnetophytes) comprise a monophyletic group or a paraphyletic one that gave rise to angiosperms. At issue is whether the Gnetophyta are the sister group of angiosperms, or whether they are sister to, or nested within, other extant gymnosperms. Numerous fossil gymnosperm clades once existed that are morphologically at least as distinctive as the four living gymnosperm
Gymnosperm

Gymnosperm is a group of spermatophyte seed-bearing plants with ovules on scales, which are usually arranged in cone-like structures. The other major group of seed-bearing plants, the angiosperms, [from the Greek, 'angion' - container] have ovules enclosed in a carpel, a sporophyll with fused margins....
 groups, such as Bennettitales
Bennettitales

Bennettitales is an extinct order of spermatophyte that first appeared in the Triassic period and became extinct toward the end of the Cretaceous....
, Caytonia and the glossopterids. When these gymnosperm fossils are considered the question of gnetophyte relationships to other seed plants becomes even more complicated.