Monoecious tree, to 5 (6) m tall; trunk 4-5 cm dbh, sometimes with prop roots at base; internodes 6-8 cm long; leaf scars to 15 cm apart. Leaf blades ca 10, spreading, usually less than 2 m long; petioles becoming rounded or obscurely flattened near base of blade, 50-75 cm long including sheath, sheathing at base, the sheath two-thirds to three-fourths as long as petiole; rachis prominently ridged just beyond base of blade; pinnae few, in 4-6 pairs, irregular in shape, 1.5-2 cm wide, 29-41 cm long, irregularly spaced, to 10 cm apart, the apex long-acuminate, falcate, the terminal pair often irregularly united, the costae many, in part slightly raised on upper surface (sharply so on drying), the larger ones 15-18 mm apart; juvenile leaves entire, bilobed as adults at apex, becoming pinnate with 2 or 3 lobes, often on one side only, with the other side entire. Inflorescences usually below leaves, +/- erect in flower, drooping in fruit, to nearly 1 m long; spathe thin, tightly sheathing peduncle, persisting and becoming weathered; spadix broomlike, on a long slender peduncle to 70 cm long, with many long thin branches mostly at right angles to axis when open; flowers tiny, in biseriate clusters of 4-13, on alternate sides of rachis, only the lowermost of each group pistillate; staminate flowers ca 0.6 mm long, the calyx much less than half as long as petals; stamens 3; filaments elongate, exserted at anthesis; staminodia usually present; pistillate flowers ca 1 mm long, the pistil as long as petals; pistillodes lacking. Fruits oblong, ca 1.5 cm long, light yellow to orange at maturity (drying black); seed 1. Croat 7010, 11020. Occasional, especially in the old forest, preferring shady moist areas near streams. Flowering mostly in the early to middle rainy season (June to September), and fruiting in late rainy to dry season. Less frequently flowering in late dry season, with fruits maturing in the early rainy season. Recognized by its broomlike inflorescence and irregularly pinnate leaves. Costa Rica to Colombia and Ecuador; mostly low elevations but to 1,200 m. In Panama, known from tropical moist forest on both slopes in the Canal Zone and in San Blas and Darien, from premontane wet forest in Veraguas (Cerro Tute) and Panama (Lago Cerro Azul), and from premontane rain forest in Panama (Cerro Jefe) and Darien (Cerro Pirre).