Gnetum

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]

Gnetum
Gnetum macrostachyum in Thailand
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Gymnosperms
Division: Gnetophyta
Order: Gnetales
Mart
Family: Gnetaceae
Blume
Genus: Gnetum
L.
Type species
Gnetum gnemon
Map showing the range of Gnetum
Distribution
Synonyms[1]
  • Gnemon Rumph. ex Kuntze
  • Thoa Aubl.
  • Abutua Lour.
  • Arthostema Neck.

Their leaves are rich in bioactive compounds 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.

Species
Phylogeny of Gnetum[6]

subsection Araeognemones

subsection Micrognemones

section Gnetum

section Scandentia

subsection Gnemonoides

subsection Stipitati

subsection Sessiles

Phylogeny of Gnetum[7][8]
section

G. buchholzianum Engler

Micrognemones

G. africanum (de Loureiro) Welwitsch

section
subsection

G. costatum Schum.

G. gnemon von Linné

Gnetum
subsection

G. raya Markgraf

G. gnemonoides Brongniart

Gnemonoides
subsection

G. leyboldii Tulasne

G. nodiflorum Brongniart

G. schwackeanum Taubert & Schenck ex Taubert & Markgraf

G. paniculatum Spruce ex Bentham

G. camporum (Markgraf) Stevenson & Zanoni

G. urens (Aublet) Blume

Araeognemones
Gnetum
section

G. microcarpum Blume

G. diminutum Markgraf

G. klossii Merrill ex Markgraf

subsection

G. parvifolium (Warburg) Cheng

G. luofuense Cheng

G. indicum (de Loureiro) Merrill

G. hainanense Cheng ex Fu, Yu & Gilbert

G. montanum Markgraf

Stipitati
subsection

G. macrostachyum Hooker

G. latifolium Blume

G. edule (Willdenow) Blume

G. neglectum Blume

G. leptostachyum Blume

G. ula Brongniart

G. tenuifolium Ridley

G. cuspidatum Blume

Sessiles
Scandentia

There are over 50 different species of Gnetum.

Uses

Many Gnetum species are edible, with the seeds being roasted, and the foliage used as a leaf vegetable.[9] The plant is harvested and yields a useful fiber. There is no sense of danger in consuming the fruit or the seeds.[10]

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.[11]

Conservation

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.

References
  1. Kew World Checklist of Selected Plant Families
  2. Ren D, Labandeira CC, Santiago-Blay JA, Rasnitsyn A, Shih CK, Bashkuev A, Logan MA, Hotton CL, Dilcher D. (2009). Probable Pollination Mode Before Angiosperms: Eurasian, Long-Proboscid Scorpionflies. Science, 326 (5954), 840-847. doi:10.1126/science.1178338
  3. Won H, Renner SS: The internal transcribed spacer of nuclear ribosomal DNA in the gymnosperm Gnetum. Molecular Phylogenetics and Evolution 2005, 36:581-597. doi:10.1016/j.ympev.2005.03.011
  4. Won, H., and S. S. Renner. 2006. Dating dispersal and radiation in the gymnosperm Gnetum (Gnetales) – clock calibration when outgroup relationships are uncertain. Systematic Biology 55(4): 610-622. doi:10.1080/10635150600812619
  5. Significance of Photosynthetic Characters in the Evolution of Asian Gnetum (Gnetales)
  6. Hou, Chen; Humphreys, Aelys M.; Thureborn, Olle; Rydin, Catarina (April 2015). "New insights into the evolutionary history of Gnetum (Gnetales)". Taxon. 64 (2): 239–253. doi:10.12705/642.12.
  7. Stull, Gregory W.; Qu, Xiao-Jian; Parins-Fukuchi, Caroline; Yang, Ying-Ying; Yang, Jun-Bo; Yang, Zhi-Yun; Hu, Yi; Ma, Hong; Soltis, Pamela S.; Soltis, Douglas E.; Li, De-Zhu; Smith, Stephen A.; Yi, Ting-Shuang; et al. (2021). "Gene duplications and phylogenomic conflict underlie major pulses of phenotypic evolution in gymnosperms". Nature Plants. 7 (8): 1015–1025. bioRxiv 10.1101/2021.03.13.435279. doi:10.1038/s41477-021-00964-4. PMID 34282286. S2CID 232282918.
  8. Stull, Gregory W.; et al. (2021). "main.dated.supermatrix.tree.T9.tre". Figshare. doi:10.6084/m9.figshare.14547354.v1. {{cite journal}}: Cite journal requires |journal= (help)
  9. Hoe, V.B. and Siong, K.H., "The Nutritional Value of Indigenous Fruits and Vegetables in Sarawak,"Asia-Pacific Journal of Clinical Nutrition, Vol. 8, no. 1, 1998, pp 24-31
  10. "Gnetum gnemon | plant | Britannica". www.britannica.com. Retrieved 2022-05-02.
  11. Kloypan, Chiraphat; Jeenapongsa, Rattima; Sri-In, Piyawit; Chanta, Surin; Dokpuang, Dech; Tip-Pyang, Santi; Surapinit, Nattanan (2012). "Stilbenoids from Gnetum macrostachyum Attenuate Human Platelet Aggregation and Adhesion". ResearchGate. 26 (10): 1564–1568. doi:10.1002/ptr.4605. PMID 22511550. S2CID 43249684.
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