Generally medium-sized woody climbers, climbing with the aid of twisted petioles. Leaves 3(-5)-foliolate, seldom simple and 3-lobed (not in Malesia); leaflets petioluled, top mostly acuminate, veins loop-like with midrib and lateral nerves curved towards apex or basal. Inflorescence terminal and axillary, many- or few-flowered; partial inflorescences cincinni, paired or simple, with bracts; bracts persistent (or caducous). Flowers bisexual, 5-merous, perianth segments (tepals) in two rows, valvate in bud, oblong, inner ones linear, deciduous; outer ones 3-5-nerved, inner ones 1-3-nerved; ovary ovoid, 4-angled, in fruit the angles grown out into 2 or 4 wings, style filiform; stamens 5, inserted opposite the outer tepals and alternating with sessile glands, or glands absent (I. celebica)', filaments straight and slightly flattened, or inwardly coiled and conspicuously flattened, each at base with two inflated, membranous, shortly stiped appendages, or appendages clavate and solid; anthers ovoid. Fruit a samara; the nut with 2 longer and 2 shorter lateral wings (or wings sometimes absent), wings membranous, suborbicular or Ungulate. Seeds with membranous testa; cotyledons free, more or less planoconvex, or slightly unequal.
Africa: present Asia-Tropical: Madagascar: present Sinohimalayan region: present
About 20 species, the majority in the Sinohimalayan region; in Malesia 9 species; in Africa and Madagascar 3 species.