Gnetophyta is a division of plants, grouped within the gymnosperms, that consists of some 70 species across the three relict genera: Gnetum, Welwitschia, and Ephedra. The earliest unambiguous records of the group date to the Jurassic, and they achieved their highest diversity during the Early Cretaceous. The primary difference between gnetophytes and other gymnosperms is the presence of vessel elements, a system of small tubes (xylem) that transport water within the plant, similar to those found in flowering plants. Because of this, gnetophytes were once thought to be the closest gymnosperm relatives to flowering plants, but more recent molecular studies have brought this hypothesis into question, with many recent phylogenies finding them to be nested within the conifers.
The gymnosperms are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae. The term gymnosperm comes from the composite word in Greek: γυμνόσπερμος, literally meaning 'naked seeds'. The name is based on the unenclosed condition of their seeds. The non-encased condition of their seeds contrasts with the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or on their own as in yew, Torreya, Ginkgo. Gymnosperm lifecycles involve alternation of generations. They have a dominant diploid sporophyte phase and a reduced haploid gametophyte phase which is dependent on the sporophytic phase. The term "gymnosperm" is often used in paleobotany to refer to all non-angiosperm seed plants. In that case, to specify the modern monophyletic group of gymnosperms, the term Acrogymnospermae is sometimes used.
Mallotus is a genus of the spurge family Euphorbiaceae first described as a genus in 1790. Two species are found in tropical Africa and Madagascar. All the other species are found in East Asia, the Indian Subcontinent, Southeast Asia, eastern Australia, and certain islands of the western Pacific. The genus has about 150 species of dioecious trees or shrubs.
Gaultheria is a genus of about 283 species of shrubs in the family Ericaceae. The name commemorates Jean François Gaultier of Quebec, an honour bestowed by the Scandinavian Pehr Kalm in 1748 and taken up by Carl Linnaeus in his Species Plantarum. These plants are native to Asia, Australasia and North and South America. In the past, the Southern Hemisphere species were often treated as the separate genus Pernettya, but no consistent reliable morphological or genetic differences support recognition of two genera, and they are now united in the single genus Gaultheria.
Gnetum gnemon is a gymnosperm species of Gnetum, its native area spans from Mizoram and Assam in India down south through Malay Peninsula, Malay Archipelago and the Philippines in southeast Asia to the western Pacific islands. Common names include gnetum, joint fir, two leaf, melinjo, belinjo, bago, and tulip.
Aporosa is a genus of flowering plant belonging to the family Phyllanthaceae, first described as a genus in 1825. It is native to China, the Indian Subcontinent, Southeast Asia, Papuasia, and Queensland.
Drypetes is a plant genus of the family Putranjivaceae, in the order Malpighiales.
Dipterocarpus is a genus of flowering plants and the type genus of family Dipterocarpaceae.
Double fertilization or double fertilisation is a complex fertilization mechanism of flowering plants (angiosperms). This process involves the joining of a female gametophyte with two male gametes (sperm). It begins when a pollen grain adheres to the stigma of the carpel, the female reproductive structure of a flower. The pollen grain then takes in moisture and begins to germinate, forming a pollen tube that extends down toward the ovary through the style. The tip of the pollen tube then enters the ovary and penetrates through the micropyle opening in the ovule. The pollen tube proceeds to release the two sperm in the embryo sacs.
The genus Tacca, which includes the batflowers and arrowroot, consists of flowering plants in the order Dioscoreales, native to tropical regions of South America, Africa, Australia, Southeast Asia, and various Oceanic islands. In older texts, the genus was treated in its own family Taccaceae, but the 2003 APG II system incorporates it into the family Dioscoreaceae. The APG III and APG IV systems continue to include Tacca in Dioscoreaceae.
Phoebe is a genus of evergreen trees and shrubs belonging to the Laurel family, Lauraceae. There are 75 accepted species in the genus, distributed in tropical and subtropical Asia and New Guinea. 35 species occur in China, of which 27 are endemic. The first description of the genus was of the type species P. lanceolata made in 1836 by Christian Gottfried Daniel Nees von Esenbeck in Systema Laurinarum, p. 98.
Arenga is a genus of palms, native to Southeast Asia, southern China, New Guinea, and northern Australia. They are small to medium-sized palms, growing to 2–20 m tall, with pinnate leaves 2–12 m long. Arenga palms can grow in areas with little sunlight and relatively infertile soil.
Actinodaphne is an Asian genus of flowering plants in the laurel family (Lauraceae). It contains approximately 125 species of dioecious evergreen trees and shrubs.
Barringtonia is a genus of flowering plants in the family Lecythidaceae first described as a genus with this name in 1775. It is native to Africa, southern Asia, Australia, and various islands of the Pacific and Indian Oceans. The genus name commemorates Daines Barrington.
Beilschmiedia is a genus of trees and shrubs in family Lauraceae. Most of its species grow in tropical climates, but a few of them are native to temperate regions, and they are widespread in tropical Asia, Africa, Madagascar, Australia, New Zealand, North America, Central America, the Caribbean, and South America. The best-known species to gardeners in temperate areas are B. berteroana and B. miersii because of their frost tolerance. Seeds of B. bancroftii were used as a source of food by Australian Aborigines. Timbers of some species are very valuable.
Spatholobus is a genus of flowering plants in the legume family Fabaceae. It includes 35 species of lianas which range from the Indian subcontinent to Indochina, southern China, and western Malesia. It grows in seasonally-dry to evergreen tropical forest and thicket, often on rocky slopes and in disturbed areas. It belongs to subfamily Faboideae.
Sciaphila is a genus of mycoheterotrophic plants in the family Triuridaceae. These plants receive nutrition from fungi and neighboring trees and have less need for photosynthesis. It is widespread in tropical and subtropical regions, found in Africa, China, Japan, the Indian Subcontinent, Southeast Asia, Latin America and on various islands Pacific Islands. The most noteworthy feature of the genus is the number of the various flower parts 99.9 percent of Monocots are trimerous, but Sciaphila spp. can have eight or even ten parts in a whorl.
Burmannia is a genus of flowering plants long thought of as related to orchids, although more recent studies suggest closer affinities with either the Dioscoreales or the Melanthiales. The plants are herbs, partially autotrophic (photosynthetic) but also partially parasitic on soil fungi.
Gnetum macrostachyum is a species of vine gymnosperm, native to tropical Asia. They are often harvested as a source of fiber.
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