The World Flora Online

Lianes'ligneuses, plus rarement arbustes ou arbres, dioïques, ramifiés et sans canaux résinifères.'Feuilles'opposées, à limbe large et réticulinerve.'Strobiles'spiciformes, à sporophylles verticillés, entremêlés de poils pluricellulaires et entourés de bractées fonctionnant comme une enveloppe.'Sporophylles'♂ formés d'une colonne portant 1-2 anthères et à enveloppe tubulaire; grains de pollen sphériques.'Sporophylles'♀ à enveloppe cupulaire; ovule 1, sessile, à tégument tubulaire dépassant l'enveloppe et entouré en outre d'un arille.'Graines drupacées entourées de la cupule persistante différenciée en une couche externe charnue et une couche interne dure, à endosperme abondant et amylacé.\n\t\t\tUn seul genre :'Gnetum , groupant 30 espèces dans les régions tropicales.

Female flowers with a close-fitting utricle resembling an ovary; ovule otherwise naked, integument produced into a straight micropylar tube exserted through the orifices of the aril and utricle, truncate, toothed or fimbriate Male flowers with a tubular envelope of 2 connate scales; anthers 2 or 1, sessile on the summit of a central column Flowers in catkin-like spikes, usually dioecious; spikes jointed, with the flowers in whorls Erect or scandent shrubs, leaves opposite, simple Seed with copious endosperm Male flowers with a tubular envelope of 2 connate scales; anthers 2 or 1, sessile on the summit of a central column Flowers in catkin-like spikes, usually dioecious; spikes jointed, with the flowers in whorls Erect or scandent shrubs, leaves opposite, simple Seed with copious endosperm

Vines evergreen, woody, less often erect shrubs or trees, dioecious or sometimes monoecious; stems with swollen nodes. Leaves opposite, petiolate, without stipules, simple, pinnately veined, margin entire. Flowers unisexual, borne in whorled, spikelike cones (here termed "spikes"), arranged in lax, dichasial cymes. Cymes terminal or lateral, sometimes arranged in dense, cauliflorous clusters on old stems. Spikes with many cupular to almost flat, annular, involucral collars, each formed by the fusion of a whorl of bracts. Male spikes with collars closely arranged and ± hiding axis (less often somewhat laxly arranged), each collar with 20-80 flowers, often also with a whorl of sterile female flowers, apical whorl with sterile female flowers only; male flowers with a cupular, succulent false perianth, usually ± obconical; stamens 2, filaments fused, exserted from false perianth; anthers opening by a common, apical slit, pollen rounded, with minute projections. Female spikes solitary or several in a panicle, often cauliflorous; involucral collars widely separated, each with 4-12 flowers; female flowers with a false perianth tightly enclosing ovule; ovule with 2 integuments, innermost integument elongated into a micropylar tube exserted from false perianth; outer integument with a fleshy, outer layer connate with false perianth and developing into a false seed coat, inner layer bony. Seeds drupelike, enclosed in a red, orange, or yellow, fleshy (rarely corky) false seed coat; female gametophyte tissue copious, succulent. Cotyledons 2. Germination epigeal.