Small, solitary or clustered, acaulescent or erect, unarmed, pleonanthic, monoecious palms. Stems rarely exceeding about 4 m in height, with very short to elongate internodes, leaf scars inconspicuous, stilt roots sometimes present. Leaves undivided and pinnately ribbed, with or without an apical notch, or regularly to irregularly pinnate, marcescent or neatly abscising; sheaths usually splitting opposite the petiole and persistent, not forming a crownshaft, or rarely neatly abscising and a crownshaft developed, variously tomentose, a tattering ligule sometimes present; petiole present or absent, variously indumentose as the rachis; expanding blades frequently reddish-tinged, leaflets single-or several-fold, the tips or margins in entire blades irregularly praemorse, the main ribs frequently bearing scales or hairs, scattered or in bands, the blade with conspicuous longitudinal veins, transverse veinlets inconspicuous. Inflorescences usually interfoliar or infrafoliar (in species with a crownshaft), solitary, protandrous, spicate or branching to 1 or 2 orders, emerging long before anthesis, erect at first, becoming curved or pendulous; peduncle very short to very long; prophyll 2-keeled, tubular, short, usually enclosed within the leaf sheath, frequently marcescent, often indumentose; peduncular bract attached a short distance above the prophyll, usually much exceeding it, otherwise similar, marcescent, rarely neatly abscising, subsequent peduncular bracts very inconspicuous; rachis usually much shorter than the peduncle; rachillae rarely exceeding about 20 in number, usually fewer, very slender to moderately robust, glabrous or densely tomentose, bearing distant or dense, spirally arranged triads, superficial or, more usually, sunken in pits, each subtended by a low rachilla bract, forming the lower lip of the pit, an upper lip sometimes also differentiated, the pits frequently bearing sparse or abundant hairs, distal-most bracts subtending paired or solitary staminate flowers; floral bracteoles very small, included within the pits; flowers opening singly, in pit-bearing species the flowers exserted one at a time. Staminate flowers sessile, ± globular in bud, symmetrical, abscising after anthesis usually leaving the calyx behind; sepals 3, distinct, imbricate, membranous, ± striate, often keeled, often ciliate-margined, sometimes tomentose, scarcely exserted from the pit; petals 3, valvate, twice as long as the sepals, somewhat hooded, very briefly joined at the base; stamens 6, filaments slender, elongate, fleshy, inflexed in bud, anthers ± oblong, the margins sometimes undulate, ± versatile, latrorse; pistillode conspicuous, columnar, as long as the petals, fleshy. Pollen ellipsoidal asymmetric, occasionally pyriform or lozenge-shaped, less frequently oblate triangular; aperture a distal sulcus, infrequently a trichotomosulcus; ectexine tectate, perforate and micro-channelled or finely perforate-rugulate, aperture margin similar or slightly finer; infratectum columellate; longest axis 27–45 µm; post-meiotic tetrads tetrahedral [5/18]. Pistillate flower ± globular, slightly larger than the staminate; sepals 3, distinct, broadly imbricate, rounded, ± striate; petals 3, distinct, exceeding the sepals, broadly imbricate, with minute, triangular, valvate tips, ± striate; staminodes 6, slender, flattened; gynoecium unilocular, uniovulate, slightly asymmetrical, ± ovoid, stigmas 3, large, fleshy, reflexed, ovule laterally attached, hemianatropous. Fruit ovoid, ellipsoidal, bilobed, or narrowly spindle-shaped and straight or curved, or even flat and 5-pointed, smooth when fresh, smooth or ridged when dry, green, white, brownish or pink turning brilliant red at maturity, the stigmatic remains basal, perianth whorls persistent; epicarp smooth, shiny, mesocarp fleshy, endocarp well developed, woody, smooth or variously ridged, with a basal rounded operculum. Seed conforming to the shape of the endocarp, attached at one side near the base, the hilum ± circular, raphe branches spirally ascending, anastomosing, endosperm homogeneous or ruminate; embryo basal. Germination adjacent-ligular; eophyll ± entire, with praemorse margins, with or without a small apical notch. Cytology: 2n = 32.
All species are plants of the undergrowth of primary tropical rain forest and often occur gregariously; they may be found at altitudes from sea level to about 1200 m in the mountains. In Malaya, Iguanura wallichiana is extraordinarily widespread, yet in Sumatra, it is local, for no obvious reason. In Borneo, many taxa are known in only very restricted areas. Iguanura melinauensis and I. elegans are found in rich alluvial soil developed at the base of limestone hills, but are not confined to this habitat, neither do they appear to be true calcicoles. Ants, flies, bees and wasps are frequent visitors to the staminate flowers of I. wallichiana (Kiew 1972), but of these, ants seem to be the most consistent visitors of pistillate flowers.