Dioecious tree, 13-30 m tall, to almost 1 m dbh; trunk of younger trees armed, the prickles large, corky, horizontally flattened, to ca 5 cm wide and 1 cm thick (somewhat rounded and numerous on juvenile plants), generally deciduous on older trees, the scar often visible; branches and branchlets with ribs extending downward from petioles and with occasional small conical prickles; outer bark thin, brown, sparsely stellate-pubescent. Leaves pinnate, generally imparipinnate or the terminal pair bearing the scar of an aborted terminal leaflet (occasionally with 1 leaflet merely appearing terminal), 16-67 cm long; petioles mostly 5-10 cm long, sparsely stellate-pubescent; leaflets 8-20 (26), subopposite to alternate, oblong-elliptic to oblong, abruptly acuminate, acute to obtuse at base, 4.5-16 (21) cm long, 1.5-5.5 (7) cm wide, sessile or obscurely petiolulate, pellucid-punctate, +/- entire and revolute on margin, dark green, shiny and sparsely stellate-pubescent above, duller and densely pubescent below, the trichomes stellate, mostly sessile; juvenile leaves as much as 1.5 m long, the leaflets 22 cm long and 7.5 cm wide. Panicles terminal and upper-axillary, 15-33 cm long, widely branched, the branches and pedicels sparsely stellate-pubescent; branchlets scaly, the scales deltoid, ciliate; pedicels to 1.5 mm long; calyx triangular, ciliate; flowers unisexual, greenish-white, 5-lobed, to 3.7 mm wide; petals +/- elliptic, acute, imbricate., 1.4-3.3 mm. long; stamens 5, alternate, broadly exserted, to 4 mm long in staminate flowers, shorter and sterile in pistillate flowers; ovary 5-lobed, pubescent; style short; stigma simple. Fruits of 1 or 2 globose follicles-, 3.5-5 mm long, punctate-verrucose; seeds dark brown, shiny, somewhat shorter than follicle. Croat 12497. Occasional in the forest, though sometimes locally abundant in older forest. Flowers from August to October; individual plants may flower for at least a month. The fruits mature from January to March. Leaves fall off in the dry season, but the new ones all grow out before flowering begins. Southern Mexico to Panama and possibly Colombia. In Panama' known from tropical moist forest in the Canal Zone, Colon, and San Blas, from premontane wet forest in Colon (Santa Rita Ridge), and from tropical wet forest in Colon (Icacal). See Fig. 296.