Gnetum | |
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Gnetum luofuense in China | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Gymnospermae |
Division: | Gnetophyta |
Order: | Gnetales Mart |
Family: | Gnetaceae Blume |
Genus: | Gnetum L. |
Type species | |
Gnetum gnemon | |
Distribution | |
Synonyms [1] | |
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Gnetum is a genus of gymnosperms, the sole genus in the family Gnetaceae within the Gnetophyta. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms, they possess vessel elements in the xylem. Some species have been proposed to have been the first plants to be insect-pollinated as their fossils occur in association with extinct pollinating scorpionflies. [2] Molecular phylogenies based on nuclear and plastid sequences from most of the species indicate hybridization among some of the Southeast Asian species. Fossil-calibrated molecular-clocks suggest that the Gnetum lineages now found in Africa, South America and Southeast Asia are the result of ancient long-distance dispersal across seawater. [3] [4]
Their leaves are rich in phytochemicals such as flavonoids and stilbenes. Of the species studied so far, Gnetum have photosynthetic and transpiration capacities which are considerably lower than those of other seed plants, due to the absence of multiple chloroplast genes essential for photosynthesis, a trait they seem to share with the other living members of Gnetophyta, Ephedra and Welwitschia , as well as conifers. [5] There are over 50 different species of Gnetum.[ citation needed ]
Phylogeny of Gnetum [6] | |||||||||||||||||||||||||||||||||
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Phylogeny of Gnetum [7] [8] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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There are around 50 different species of Gnetum. The Catalogue of Life lists 44 species. [9]
Many Gnetum species are edible, with the seeds being roasted, and the foliage used as a leaf vegetable. [10] The plant is harvested and yields a useful fiber.[ clarification needed ] There is no sense of danger in consuming the fruit or the seeds. [11]
There is also a study done on the plant to see if it has any medicinal properties, finding some anti-coagulation effects due to its stilbenoid content. The family Gnetaceae is well known as a rich source of plant-derived stilbenoids as well as Cyperaceae, Dipterocarpaceae, Fabaceae, and Vitaceae. [12]
Some species of Gnetum are in danger of dying out. The habitats are being removed with the trees being cut down to create industry. The tropical rainforest are being destroyed so many of the species are going extinct such as Gnetum oxycarpum. The rainforests are being torn down and being turned into farmland. Gnetum live in only a small part of the rainforest.
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.
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, while all others 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 (Indonesian), bago (Filipino), and tulip.
Tabernaemontana is a genus of flowering plants in the family Apocynaceae. It has a pan-tropical distribution, found in Asia, Africa, Australia, North America, South America, and a wide assortment of oceanic islands. These plants are evergreen shrubs and small trees growing to 1–15 m tall. The leaves are opposite, 3–25 cm long, with milky sap; hence it is one of the diverse plant genera commonly called "milkwood". The flowers are fragrant, white, 1–5 cm in diameter.
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 angiosperms. This process involves the fusion of a female gametophyte or megagametophyte, also called the embryonic sac, with two male gametes (sperm). It begins when a pollen grain adheres to the stigmatic surface of the carpel, the female reproductive structure of angiosperm flowers. The pollen grain begins to germinate, forming a pollen tube that penetrates and extends down through the style toward the ovary as it follows chemical signals released by the egg. The tip of the pollen tube then enters the ovary by penetrating through the micropyle opening in the ovule, and releases two sperm into the embryonic sac (megagametophyte).
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.
Daphniphyllum is the sole genus in the flowering plant family Daphniphyllaceae and was described as a genus in 1826. The genus includes evergreen shrubs and trees mainly native to east and southeast Asia, but also found in the Indian Subcontinent and New Guinea.
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.
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.
A seed plant or spermatophyte, also known as a phanerogam or a phaenogam, is any plant that produces seeds. It is a category of embryophyte that includes most of the familiar land plants, including the flowering plants and the gymnosperms, but not ferns, mosses, or algae.
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.