Solitary, stemless or short-trunked, unarmed, pleonanthic, dioecious palm. Stem extremely short, internodes short, obscured by a loose network of long, slender, straight, sheath fibres. Leaf pinnate; sheath soon disintegrating into a mass of long straight fibres resembling horse hair; petiole erect, long, slender, grooved adaxially at the base, becoming cylindrical distally; leaflets very regular except for the lower-most which may be irregular, stiffly horizontal, the lowest very narrow, the middle lanceolate, the terminal very short, shiny dark green, a midrib and a pair of marginal veins prominent abaxially, the submarginal veins forming a prominent ridge with a resulting outer groove along the leaflet margins, transverse veinlets not evident. Inflorescences, the staminate and pistillate dissimilar; staminate short, racemose, recurved at anthesis, branched to 1 order; peduncle moderate, rounded, glabrous; prophyll tubular, short, shallowly 2-keeled, rounded to a shallow point, splitting apically; complete peduncular bracts l, similar to the propyll but longer, other peduncular bracts few (5 according to Cook) large or small and shallow; rachis slightly longer than the peduncle, bearing spirally arranged, short, terete branches, each subtended by a small pointed bract; first-order branches each bearing ca. 6(–9), crowded, staminate flowers, subtending bracts small, pointed, membranous or not evident. Staminate flowers with a short terete stalk; perianth consisting of a low membranous rim or absent; floral receptacle chunky with several flat sides all bearing irregularly to somewhat spirally arranged stamens, filaments very short, appressed, or briefly elongate, anthers short, rounded or ± elongate, basifixed, latrorse; pistillode terminal, conical, whitish, irregular in position. Pollen brevi-ellipsoidal to spheroidal, usually ± symmetric; aperture a distal brevi sulcus or large pore; ectexine semi-tectate, foveolate or reticulate, aperture margin psilate; infratectum columellate; longest axis 70–85 µm [1/1]. Pistillate inflorescence head-like, unbranched; prophyll tubular, short, 2-keeled laterally, flattened, pointed, splitting along one side; peduncular bracts several, the first complete, tubular, rounded, with a short pointed tip, splitting apically on one side, the second and third bracts incomplete, short, united basally to form a tube, distal parts distinct, triangular, fourth to sixth bracts also united basally into a shorter tube with distinct, tapering tips, seventh and eight bracts united basally on one side, open on the other side. Pistillate flowers spirally arranged, closely appressed, each subtended by a bract; sepals ± 4, narrow, elongate; petals ± 4, like the sepals but longer and somewhat wider, variously wrinkled; staminodes apparently absent; gynoecium consisting of ca. 8 carpels, connate laterally, ovarian part terete, tapering into an elongate, cylindrical style and ca. 8, curly, elongate stigmas, conduplicately folded, bearing stigmatoid tissue along the margins. Fruits borne in large head-like clusters of 3–6, clusters smaller than those of Phytelephas, each fruit rounded, covered in large, pointed warts, stylar remains terminal, forming a large beak; epicarp with short, close fibres, mesocarp fibres fine, endocarp shell-like with adherent fibres enclosing each seed. Seed ± kidney-shaped, hilum basal, raphe fibres parallel, ascending, with short branches forming grooves in the endosperm, endosperm homogeneous, very hard; embryo lateral near the base. Germination remote-ligular; eophyll pinnate. Cytology not studied.