Dioecious tree, (3) 6-12 (20) m tall; trunk 10-15 (20) cm dbh, armed, the prickles many, large, corky, oval or rounded in basal outline, the apex rounded with a sharp point set somewhat off-center; outer bark +/- smooth, light brown, with many raised lenticels; inner bark tan; wood pale yellow, the cambial layer fluted. Leaves alternate, pinnate, 15-50 cm long, conspicuously pubescent (particularly below), the trichomes erect, simple; petioles terete; rachis margined above, sometimes bearing small prickles; leaflets 15-27, subopposite, +/- sessile, ovate to oblong or oblong-elliptic, acuminate, acute to rounded at base, usually inequilateral at base, 2.5-10 (15) cm long, 1.5-3.5 cm wide, entire or crenulate, obscurely pellucid-punctate, sometimes glabrate in age above, rarely with a few prickles on midrib below. Panicles terminal or upper-axillary, +/- congested, to 21 cm long, the branches short, sparsely puberulent; pedicels 2-3.7 mm long, glabrous or crisp-pubescent; flowers unisexual, 5-parted, 2.7 mm long; calyx ca 1 mm long, usually glabrous, rounded at apex; petals elliptic, boat-shaped, spreading, white to greenish-white, the veins prominent, 2-2.3 mm long, rounded at apex, glabrous or inconspicuously pubescent inside; stamens of staminate flowers 5, included or exserted and spreading.. 1.7-2.7 mm long, the anthers about as long as or much shorter than filaments, the pistillode small, 1-4-lobed, the styles 1-4; pistillate flowers not seen. Fruits of (2) 4 (5) follicles, tan or brown, glabrous, the valves persistent, muricate, the inner valve whitish, curling from the base to force seed from follicle; seeds 1 per follicle, +/- globose or ovoid, black, shiny, 2.5-3.3 mm long, suspended on a strong slender fiber. Croat 5430. Frequent in the forest. Flowers in the late dry season (March and April). The fruits develop soon but may persist for a long time, maturing from April to October (sometimes to December). Leaves are shed in the dry season, and the trees may be bare for more than a month. Ants may inhabit old spines and hollow parts of some stems. Panama and possibly Costa Rica. In Panama-, known principally from tropical moist forest on the Pacific slope in the Canal Zone, Panama, and Darién known also from tropical dry forest in Los Santos, from premontane moist forest in Coclé (La Pintada), and from premontane wet forest on Coclé (El Cope). See Fig. 299 and fig. on p. 20.