Gnetum L.

Glabrous trees, shrubs or, for the greater part, vines. Leaves decussate, simple, entire, penninerved, exstipulate, mostly provided with fine, pellucid lines (spicular cells) parallel to the secondary nerves and then bearded on fracture. Spikes ramified or simple, axillary or often cauline, dioecious, each one with 2 opposite basal scales and several collars containing moniliform hairs and sessile flowers, either numerous spirally arranged male ones below a ring of some sterile female ones, or a ring of few fertile female ones. ♂ Flower: a claw-shaped, transversely splitting perianth and a central stamen with 2 (in G. gnemonoides one) apical, yellow microsporangia that open by an apical median split. ♀ Flower: a fleshy outer envelop ('perianth') and 2 thin inner ones ('integuments'), the innermost with a long, slender, apical tube, and an orthotropous ovule; sterile ♀ flower without the middle envelop. Fruit pink (in G. neglectum and G. oxycarpum yellow), consisting of the fleshy outer envelop, which in some spp. is narrowed into a stalk, the hardened, ribbed middle envelop, the thin, silky, inner envelop, and a large, horny seed with small embryo.

All species inhabit the tropical rainforest below 1500 m altitude, except G. microcarpum which has been reported from Mt Tahan (Pahang, Mal. Pen.) at ca 2000 m. Large-leaved and-fruited taxa are produced in the moist air of mountain gorges. Small-leaved taxa occur both in the rain forest (G. diminution and G. microcarpum f. silvestre) and in drier localities; examples of the first are represented by G. montanum f parvifolium in E. China and G. microcarpum f. campestre in the Malay Peninsula, examples of the latter are G. latifolium var. minus and G. leptostachyum var. abbreviatum, all growing near the lower limit of the cloudy forest.Most Malaysian species are tall lianas, but G. costatum and G. gnemon are arboreous, though the latter species is sometimes climbing as has repeatedly been reported from New Guinea.According to RIDLEY ( RIDLEY Disp. 1930 p. 240, 352 ) the pink fruits of Gnetum are dispersed by birds, but some are probably disseminated by water, e.g. G. gnemonoides with large corky fruits 7½ by 3¾ cm. Gnetum seeds are sometimes found in excreta of civet-cats (Viverridae). HEMSLEY reported Gnetum seeds from the beach ( HEMSLEY Rep. Bot. Chall. 1 3 1884 297 ).

Uses. The inner bark of several species, G. gnemon, G. latifolium, and others, is highly praised for its fibre, and is used all over Malaysia for twisting thread, string and cordage. The fibre is strong and durable in seawater and is mostly used for fishing nets and lines; in Papua carrying nets are made from it. If the fibre could be purified it would do exceedingly well for paper. G. gnemon is principally cultivated as a fruit tree, the embryo being pounded and eaten roasted, but also cooked in soup. Seeds of some other species are also used. The flush and inflorescences of G. gnemon are cooked in soup or eaten as vegetable which in the raw state causes a little itching in the mouth. Trees are sometimes coppiced for rapid production of flush. The only species really cultivated is G. gnemon var. gnemon; it is a straight tree, leafy from the base; it is sometimes planted in small orchards, but mostly in mixed gardens. It is found, outside Java, not rarely in old clearings and secondary forest ( HEYNE Nutt. Pl. 1927 p. 121-125 ).