Fisch. & C. Meyer, Mém. Acad. Imp. Sci. Saint-Pétersbourg, Sér. 6, 6:149. 1840 Palo santo, Guayabo hormiguero, Vara santa Dioecious tree, usually 10-20 m tall; trunk smooth, 12-30 cm dbh; bark light brown, thin, peeling off; stems hollow. Petioles very short or to 2 cm long, canaliculate; blades mostly oblong-elliptic, acuminate, obtuse at base, 15-30 cm long, 4-12 cm wide, glabrous but with the veins below strigose (especially midrib). Inflorescences from upper axils; staminate inflorescences of spikes to 35 cm long and 1.5 cm wide; flowers subsessile, usually in pairs, emerging one at a time from densely pubescent, spathaceous ocreolae; perianth greenish, in one series of 3 linear and 3 narrowly triangular tepals 3-4 mm long, connate for about half their length; stamens 9, exserted; anthers introrse, versatile. Pistillate inflorescences of racemes to ca 20 cm long (to 30 cm in fruit); pedicels 2-9 mm long; calyx sericeous, ca 1 cm long at anthesis (greatly accrescent and becoming red in age), the lobes narrowly triangular to linear, 2-3 times the length of the tube and spreading at anthesis; petals +/- linear, exceeding tube, fused to base of tube; styles 3, the inner surface stigmatic in upper two-thirds. Achenes sharply trigonous (the surfaces +/- flat), 8-12 mm long, shiny, brown, persistent within and dispersed by the enlarged calyx, the calyx to 6 cm long, pubescent, 3-winged, the wings pinkish, spreading, 3.5-4.5 cm long, 6-7 mm wide. Croat 4633, 8165. Usually locally common; otherwise only occasional in both the young and old forests. Plants may begin to flower when as little as 11 m tall and 12 cm dbh. Flowers from February to April, chiefly in March. The fruits begin to mature by February and are dispersed chiefly in March and April but also in May. Plants lose their leaves in July and August.