Gnetum


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Gnetum

 

the only genus of the Gnetaceae family. There are about 40 species, distributed in humid tropical forests, particularly in South and Southeast Asia but also in South America and western tropical Africa. They are chiefly lianas, but some, such as G. gnemon, are small trees or bushes. The leaves are opposite, broad, integral, leathery, penninervate, with typical network veining. The plants are diclinous. Both the micro- and megastrobiles are gathered into whorls. The female gametophyte lacks archegonia, and egg cells are formed from free nuclei in the upper part of the gametophyte. When the seed ripens, the internal cover of the megastrobile forms a hard, rocklike layer, and the brightly colored surface becomes fleshy.

In tropical Asia several Gnetum species, for example, G.gnemon, are cultivated for their edible seeds. Young leaves and the strobiles are also used as food. G. ula provides edible oil.

REFERENCE

Takhtadzhian, A. L. Vysshie rasteniia, vol. 1. Moscow-Leningrad, 1956.

A. L. TAKHTADZHIAN

References in periodicals archive ?
The low photosynthetic rates observed here are also characteristic of shade-adapted species (Kitajima, 1996b), and are consistent with the patterns reported by Feild & Balun (2008) for adult Gnetum plants, although from different species.
Since the beginning of this century, there has been speculation that the female gametophyte of Gnetum is evolutionarily juvenilized (paedomorphic) and that this may account for its highly reduced and divergent morphology at sexual maturity (Coulter 1909; Favre-Duchartre 1965; Takhtajan 1972, 1976; Takhtadzhian 1991).
Annual sale quotas consumer values from from 2012 unitprice quotas attributed attributions (XAF/kg) by government (Tons) (X million XAF) (b x c) Funtumia africana 7 000 200 1 400 Rauvolfia vomitoria 6 450 3 Pausinystalia 655 650 426 johimbe Gum arabic 116 455 53 Gnetum spp.
The dietary fiber sources used in this study included 'gari' Ex Manihot esculenta, Musa paradisiaca (matured green plantain), Gnetum africana leaves and Telfaria occidentalis leaves.
Pollination biology of Gnetum (Gnetaceae) in a lowland mixed dipterocarp forest in Malaysia.
Li JB, Lin M, Li SZ, Song WZ (1991) Studies on the structure of gnetifolin A of Gnetum parvifolium (Warb.
n] Services SE1 SE2 Sum NCI Sum (CI Total of product +NCI) TABLE 4 Percentage of households obtaining cash and non-cash income from each NTFP per ethnic group per country Ethnic Cameroon group NTFPs Scientific Cash Non- names income cash income Okok Gnetum 62.
Gnetum and angiosperms: Molecular evidence that their shared morphological characters are convergent, rather than homologous.
Heterochrony and developmental innovation of female gametophyte ontogeny in Gnetum, a highly apomorphic seed plant.
Efforts to find homologies break down, however, when one looks at the whorled positions of female "flowers," or the even more puzzling arrangement of male flowers in Gnetum.