| Species Separate descriptions are available for the following species: G. camporum G. gnemon G. leyboldii G. nodiflorum G. paniculatum G. urens There are very few data on the following species, treated in the "Range" and "Remarks" sections, below: G. arboreum G. buchholzianum G. africanum G. contractum G. costatum G. cuspidatum G. diminutum G. gnemonoides G. hainanense G. klossii G. latifolium G. leptostachyum G. loerzingii G. macrostachyum G. microcarpum G. montanum G. neglectum G. oblongum G. oxycarpum G. ridleyi G. schwackeanum G. tenuifolium G. ula G. venosum |
Common Names
Taxonomic notes
The genus has been subdivided by Markgraf (1930, in (5)) as follows:| Section | Subsection | Species |
| Gnetum | Gnetum | G. gnemon and one other Indomalesian tree species |
| Micrognemones | Two species of African lianas | |
| Araeognemones | Nine species of Neotropical lianas | |
| Cylindrostachys | About 19 species of Asian and Indomalesian lianas, incl. G. arboreum, G. contractum, G. cuspidatum, G. diminutum, G. gnemonoides, G.hainanense, G. klossii, G. latifolium, G. leptostachyum, G. loerzingii, G.macrostachyum, G. microcarpum, G. montanum, G. neglectum, G. oxycarpum, G.ridleyi, G. ula, and two other species. |
Description
Monoecious or dioecious plants, mostly woody climbers, rarely shrubs or trees. Leaves elliptic, with netted veins and drip tips at their ends. Flowers monosexual, in catkin-like formations; male flower consists of a stamen and perianth, and female flower of an ovule with 2 integuments and perianth (2, 9).Range
Indomalaysia, tropical parts of West Africa, Fiji and the northern regions of South America (6).The following species are found in Malesia or SE Asia (2): Gnetum costatum, G. gnemonoides Brongniart, G. klossii Merrill, G. latifolium Blume, G. leptostachyum Blume, G. loerzingii Markgraf, G. macrostachyum Hooker f., G. microcarpum Blume, Gnetum montanum Markgraf, and Gnetum ula Brongniart.
Gnetum arboreum Foxworthy is restricted to a small portion of Luzon, Philippines (Markgraf 1930,in (2)).
Gnetum contractum Markgraf is found in Travancore, India (Markgraf 1930, in (2)).
Gnetum diminutum Markgraf is restricted to a small portion of Sarawak, Malaysia (Markgraf 1930,in (2)).
Gnetum hainanense Cheng is found in China: Hainan.
Gnetum neglectum Blume is restricted to a small area in E Borneo (Markgraf 1930, in (2)).
Gnetum oxycarpum Ridley is restricted to the Mentawi Islands near Sumatra (Markgraf 1930, in (2)).
Gnetum ridleyi Gamble is restricted to a small area in Pahang, Malaysia (Markgraf 1930, in(2)).
Big Tree
Oldest
Dendrochronology
There is no record of any work being done with G. gnemon, and as the remaining species of the genus are all woody vines, they are presumably not usable in dendrochronology.Ethnobotany
"When young they are sometimes cooked as a vegetable. The stems are very fibrous and in parts of New Guinea the fibres are used to make string, etc." (7).Ethnopharmacological studies have found C-glycosyl-flavones; and a group of complex stilbenes and stilbene-substituted benzofurans. Gnetol, a hydroxylated stilbene, occurs in G. ula. "Lignans are of the guaiacyl-syringyl-type; the antiasthmatic properties for which G. parviflorum is used in Chinese medicine have been ascribed to the presence of demethylcoclaurine hydrochloride" (6).
Observations
Remarks
"[L]ocating and collecting tropical lianoid Gnetum species is difficult because the fertile portions necessary to identify them as species of Gnetum often occur in the high forest canopy, whereas the more easily accessible stems visible at ground level cannot be identified for certain as stems of Gnetum rather than as any of numerous other lianas" (2).Gnetum leptostachyum Blume and Gnetum montanum Markgraf are listed as threatened in Viet Nam by the World Conservation Monitoring Centre.
Gnetum africanum Welwitsch: See (5).
Gnetum ula Brongniart: See (4).
"At Mt. Bosavi a protected area is proposed, occupying and sharing areas of the Southern [Highlands], Western and Gulf Provinces [of Papua New Guinea]. The mountain is an isolated volcano south of the Central Divide. The area has locally endemic plant species, e.g. the only known site of an endemic Gnetum species. There are also many bird species. The area should extend down to lowland forest to preserve areas dominated by Vatica massak and other lowland species typical for this region" (8).
For the following species, I know nothing but their name: Gnetum buchholzianum, Gnetum cuspidatum Blume, Gnetum oblongum, Gnetum schwackeanum, Gnetum tenuifolium, Gnetum venosum.
Citations
(1) Maheshwari & Vasil 1961.(2) Carlquist 1996a.
(3) Carlquist 1996b.
(4) Augustine, A. C. and L. D'Souza. 1997. Somatic embryogenesis in Gnetum ula Brongn. (Gnetum edule) (Willd) Blume. Plant cell reports 16(5): 354.
(5) Shiembo, P.N., A.C. Newton and R.R.B. Leakey. 1996. Vegetative propagationof Gnetum africanum Welw., a leafy vegetable from West Africa. The journal of horticultural science 71(1):149.
(6) Schultes & Raffauf 1990.
(7) http://www.ncl.ac.uk/dept/moorbank.html#gymn
(8) Filer 1991.
(9) Vidakovic 1991.
See also:
Friedman, William E. and Jeffrey S. Carmichael. 1998. Heterochrony anddevelopmental innovation: evolution of female gametophyte ontogeny in Gnetum, a highly apomorphic seed plant. Evolution 52(4):1016.
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This page is from the Gymnosperm Database
URL: http://www.geocities.com/RainForest/Canopy/2285/gn/gn/gnetum.htm
Edited by Christopher J. Earle
E-mail:earlecj@earthlink.com
Last modified on 3-Jan-1999