Functionally monoecious tree, to 40 m tall, to 1 m dbh; outer bark hard, thin, light brown, sandpapery, the lenticels many, closely spaced, raised; inner bark thick, tan, granular; sap with strong, pungent odor. Leaves deciduous; stipules ovate, 5-8 mm long, axillary, caducous; petioles to 25 cm long, densely to sparsely stellate-pubescent; blades deeply and palmately 3-5-lobed, rounded to acute at apex of lobes, cordate at base, to 35 cm long and 45 cm wide, glabrous above except on veins especially near base, softly stellate-arachnoid below to glabrate in age; basal veins usually 5-7, each lobe with 3-7 pinnate veins. Panicles or racemes axillary or subterminal; flowers bisexual or functionally staminate, predominately staminate, with a strong spicy odor; calyx bowl-shaped, greenish, ca 2 cm broad and 1 cm deep, flexible, coriaceous, densely covered outside with short, violet-purple, stellate trichomes, striate and glabrate inside, the lobes acute, recurved; petals lacking; gynophore of staminate flowers hook-shaped, shorter than rim, sparsely glandular-puberulent, also hispidulous at apex; stamens 15, sessile on a raised disk at apex of gynophore; anthers extrorse, dehiscing in bud; pollen +/- tacky; pistil rudimentary, sunken deeply at base of staminal disk, produced above into a slender style, gynophore of pistillate flowers similar and shorter, the staminal disk reduced, the nonfunctional stamens much shorter than the pistil; pistil stellate-tomentulose, 5-carpellate, 5-sulcate, the carpels separating at maturity; style solitary, stout, bent to one side; stigma capitate. Follicles obovoid, to 8 cm long and 5 cm wide, short-tomentose outside, with dense, erect, orangish, stinging trichomes inside, opening very widely along the ventral suture, the periderm woody, 5-7 mm thick; seeds 2-4, oblong-ellipsoid, ca 2 cm long, 1.2 cm diam, covered with trichomes similar to inside of pod, then with a thin, tough, chestnut-brown layer, and then with a thin white layer. Croat 13244. Frequent in the forest. The plant loses its leaves at the beginning of the dry season. After a short span of leaflessness, new leaves are produced. Flowering occurs usually every 2 years and the flowers appear shortly before or shortly after the onset of new leaves, usually in February. The fruits mature about 1 year later, mostly from January to April. Elsewhere in Panama the species may flower twice a year, in November or December and again in March. All fruits on an individual tree dehisce within about 1 month. Those observed by J. Derr (pers. comm.) in Guanacaste, Costa Rica, fell to the ground within 1 week. The seeds are heavily parasitized by cotton stainer bugs (Dysdercus bimaculatus), and any seeds falling beneath the tree are killed by these bugs. Pods that are removed some distance by monkeys, agoutis, or other animals usually have some uneaten seeds discarded because the frugivore becomes distracted by the irritating trichomes lining the pod (Janzen, 1972). In Guanacaste fruit pods are opened by parrots and orange-chinned parakeets and by magpie jays which take the seeds after the pods have opened (J. Derr, pers. comm.). Mexico to Peru and Brazil; West Indies. In Panama, a typical component of tropical dry forest (Holdridge & Budowski, 1956) and of tropical moist forest (Tosi, 1971); known from tropical moist forest in the Canal Zone, San Blas, Panama, and Darien, from tropical dry forest in Coclé, from premontane moist forest in the Canal Zone and Panama, and from premontane wet forest in Chiriqui. Reported from tropical wet forest in Costa Rica (Holdridge et al., 1971).