Small to moderate, solitary or clustered, sometimes stoloniferous, spiny, pleonanthic, monoecious palms. Stem often very short, the plant then ± acaulescent, or erect, rarely branching aerially, becoming bare, conspicuously ringed with leaf scars and usually bearing horizontal rows or rings of robust black spines. Leaves few to numerous, pinnate or entire bifid, spirally arranged, distichous or tristichous (Aiphanes leiostachys) neatly abscising; sheaths tubular at first, soon disintegrating into a weft of fibres and broad shreds, usually densely spiny and/or tomentose, distally prolonged into a tubular, tattering ligule; petiole short to long, adaxially channelled in proximal part, flattened or angled distally, abaxially rounded or angled, usually variously golden-yellow to black-spiny and sometimes also tomentose, the spines themselves often bearing caducous tomentum; rachis (or axis of entire leaf) adaxially ± angled, abaxially rounded, often variously spiny and/or tomentose or glabrous; blade where undivided, with a shallow to deep apical notch, the margins praemorse, the main ribs unarmed or spiny on abaxial and/or adaxial surfaces, leaflets, where blade divided, narrow lanceolate to broad rhomboid, regularly arranged or grouped, held in one plane or twisted into several planes, proximal margins entire, the apical praemorse, shallowly or deeply lobed, variously tomentose or bristly or glabrous, variously armed with short to long spines along veins on one or both surfaces and along margins, transverse veinlets obscure. Inflorescences solitary or rarely multiple, interfoliar, spicate (rarely) or branching to 1 order only, very rarely to 2, apparently protandrous; peduncle elongate, curved to pendulous, ± elliptic to circular in cross-section, unarmed or sparsely to fiercely armed with spicules and spines, glabrous or tomentose; prophyll usually lanceolate, ± beaked, flattened, 2-keeled, tubular, enclosing the inflorescence in bud, splitting longitudinally and tattering apically, but persistent, variously glabrous or tomentose, unarmed or spiny; peduncular bract inserted near the prophyll, much longer, ± terete, sometimes beaked, unarmed or variously spiny, persistent; rachis (where inflorescence branched) shorter than the peduncle, proximally often armed, distally usually unarmed, often scaly or tomentose, bearing spirally arranged, evenly spaced rachillae each subtended by a small triangular bract; rachillae slender, usually elongate, often spreading, straight or flexuous, with a short to long, basal bare portion, the whole glabrous or more usually scaly or tomentose, flowers borne spirally in triads proximally, distally the rachillae bearing solitary or paired staminate flowers, rarely the rachillae bearing staminate flowers only, very rarely flowers borne in tetrads of 2 pistillate and 2 staminate (according to Read 1979), flower groups superficial or sunken in pits, the rachilla bracts forming the lower lips of the pits; floral bracteoles minute. Staminate flowers usually small, sessile or with a brief stalk; sepals 3, distinct, or connate and spreading in a 3-lobed ring, triangular, membranous; petals 3, distinct or minutely connate basally, valvate, triangular, rather fleshy, much longer than the calyx, ± ovate to triangular, adaxially with impressions of the stamens; stamens 6, filaments short, fleshy, wider and minutely connate basally and/or briefly epipetalous, anthers orbicular, ± rectangular, or linear, medifixed, versatile, latrorse; pistillode minute, conical or trifid. Pollen ellipsoidal, usually with either slight or obvious asymmetry; aperture a distal sulcus; ectexine tectate, perforate, micro-channelled and rugulate; infrequently coarsely perforate and spinose or, coarsely perforate and verrucate, aperture margin usually slightly finer; infratectum columellate; longest axis 24–34 µm [11/23]. Pistillate flowers larger than the staminate, sessile; sepals 3, distinct, broad, imbricate; petals 3, exceeding the sepals, fleshy, connate in the basal ca. 1/2, apically with 3, triangular, valvate lobes; staminodal ring 6-toothed, adnate to the corolla tube; gynoecium ovoid, trilocular, triovulate, stigmas 3, becoming reflexed at anthesis, ovules ?orthotropous, laterally attached. Fruit 1-seeded, ± globose, brilliant red at maturity, stigmatic remains small, apical; epicarp smooth, mesocarp thick, fleshy, fibrous, endocarp thick, very hard and woody, usually uneven, with 3, usually equatorially placed pores, surrounded by radiating fibres. Seed irregularly globose, basally attached, endosperm homogeneous with a central cavity; embryo lateral, opposite one of the pores. Germination adjacent-ligular; eophyll very shallowly to deeply bifid with praemorse tips, frequently densely spiny. Cytology: 2n = 30.