(L.) H.B.K., Nov. Gen. & Sp. 5:149. 1822
Nance, Nance blanco, Nance Colorado
Tree., 4-13 m tall, to 30 cm dbh; bark fissured and lenticellate; wood dull reddish-brown, hard, heavy; younger parts densely downy-tomentose (sparsely on upper leaf surface and becoming glabrate); stems bearing prominent leaf scars. Petioles ca 1 cm long, stout; blades obovate to elliptic or ovate, acuminate, narrowed to an acute or obtuse base, 7-14 cm long, 3-8 cm wide, densely pubescent below becoming glabrate except on midrib in age; midrib ± arched. Pseudoracemes terminal, usually solitary, to 20 cm long; pedicels to 1.5 cm long; flowers many, yellow, becoming red-orange in age; sepals each bearing 2 conspicuous glands, blunt, recurved, glabrous inside; petals clawed, 10-13 mm long, the blade orbicular, often concave, ± equaling length of claw, the margin irregular, 1 petal often smaller and held somewhat erect, the others spreading to reflexed; stamens 10, 4-5 mm long, interspersed with long straight trichomes; anthers introrse equaling length of styles, the thecae prominently raised, shedding pollen in bud, the connective thickened; ovary usually pubescent; styles 3, distinct, slender, longer than stamens, persisting on young fruits. Drupes ± globose, 1-1.5 cm diam, green turning yellow to reddish; pyrenes 1-3. Croat 6068, 8702.
Locally common along the shore; infrequent in the forest, usually near old settlement sites. Flowers from November to July, principally from March to June. Each tree flowers for about 6 weeks. The fruits mature principally in August and September. Leaves turn old and reddish, falling in the dry season and gradually growing out again in March just before the greatest flush of flowering. Allen (1956) reported that the species had fruits during April and May in Costa Rica, but the fruits were probably not ripe.
Byrsonima crassifolia may be confused with B. cumingiana Adr. Juss., which ranges from Nicaragua to Colombia. B. cumingiana is distinguished by having a glabrous ovary and leaves that are more thickly coriaceous and rugose above.
The fruits are probably dispersed by large birds and by mammals.
Veracruz, Mexico, south to Brazil and Paraguay; West Indies. In Panama, widespread and ecologically variable; known from tropical moist forest in the Canal Zone, Bocas del Toro, Veraguas, Herrera, Coclé, Panama, and Darién, from premontane dry forest in Coclé, from tropical dry forest in Los Santos and Panama, from premontane moist forest in the Canal Zone, from premontane wet forest in Chiriqui, and from tropical wet forest in Colon. Tosi (1971) listed this species as characteristic of tropical dry and tropical moist forests in Panama.