Monoecious or dioecious tree, to 30 m or more tall with trunk 30 cm or more diam, the upper part of the trunk very broad with old leaves and inflorescences persisting for several seasons. Blades unarmed, 5-10 m long, often held in a vertical plane; petioles 30-60 cm long, canaliculate on upper surface; rachis canaliculate on upper surface at base of blade, becoming sharply triangular toward apex; leaflets very irregular, l m or more long, 1-4.5 cm wide, blunt and inequilateral, one side of apex 2.5-3.5 cm longer than the other, the midrib prominent on upper surface, the reticulate veins drying prominent, the pinnae inserted at staggered angles and often in clusters of 2 or 3, the lowermost of each cluster almost erect; juvenile leaves at first entire, the surface much pleated, soon splitting into separate, +/- regular pinnae, the uppermost +/- united. Spathe to 3 m long, woody, deeply grooved on outside, with a long point, persisting; peduncles massive, usually longer than fertile part of spadix; spadix yellowish-white, over 1 m long, with numerous simple branches usually less than 20 cm long, usually bearing staminate flowers near the end and pistillate flowers closer to peduncle (some trees bear only staminate flowers and others only pistillate flowers); staminate flowers soon falling, their petals subulate,1.5-2 cm long; stamens 6, often exserted from between petals, less than 5 mm long; filaments short and thin; anthers to ca 4 mm long; pistillate flowers with petals imbricate at base, narrowed toward apex; fruiting inflorescences massive, the rachillae coarse and heavily scarred by old fruit attachments. Fruits +/- oblong, brownish-orange, 6 cm or more long, about 3 cm thick, enveloped at base by the large accrescent calyx, the surface minutely longitudinally striate, the beak abrupt, 5-8 mm long; seeds 1-3. Croat 6100. Common throughout the island, especially near the shore and in younger areas of the forest; juvenile plants more abundant than adult. Flowers from April to September with most flowers appearing in the early rainy season. By the end of the rainy season fruits are already of mature size, but green. Many mature by the middle of the dry season, then begin to disappear slowly, and are mostly gone by July. The fruits are usually present and mature at the time of flowering. Probably most plants bear both staminate and pistillate flowers on the same inflorescence; however, staminate plants (and pistillate, fide Bailey, 1943) occur in smaller numbers. Costa Rica and Panama; additional field work will probably show the species to range from at least Belize to Colombia. In Panama, common in and characteristic of tropical moist and premontane wet forests (Tosi,1971); as for most palms, few collections exist, but the species has been seen or collected on both slopes of the Canal Zone and in Colón, Panama, and Darien.