19. Prunus havardii (W. Wight) S. C. Mason, J. Agric. Res. 1: 153, 176. 1913.
Amygdalus havardii W. Wight in W. R. Dudley et al., Dudley Mem. Vol., 133. 1913 (as harvardii)
Shrubs, suckering unknown, ˂much branched˃, 10–20 dm, thorny. Twigs with axillary end buds, puberulent. Leaves deciduous; petiole 1–3 mm, glabrous or puberulent, eglandular; blade rhombic, obovate, or fan-shaped, 0.5–1.6(–2) × 0.2–0.8(–1.4) cm, base broadly obtuse or rounded to nearly truncate, margins serrate or dentate in distal 1/2, teeth blunt to sharp, some callus-tipped, rarely glandular, apex rounded to obtuse, surfaces puberulent. Inflorescences solitary flowers. Pedicels 0 mm. Flowers ˂unisexual, plants dioecious˃, blooming at leaf emergence; hypanthium campanulate, 2.5–3 mm, glabrous externally; sepals spreading to reflexed, triangular, 0.7–1 mm, margins entire, ˂sparsely ciliate˃, surfaces glabrate; petals white, obovate, 2 mm; ovaries hairy. Drupes reddish brown, ovoid, 8–11 mm, puberulent; ˂hypanthium tardily deciduous˃; mesocarps leathery to dry (splitting); stones ovoid, slightly flattened.
Flowering Apr–Jun; fruiting Jun–Aug. Draws, dry rocky slopes of canyons, limestone soil, igneous rock; 700–1700 m; Tex.; Mexico (Chihuahua).
Prunus havardii is endemic to the Chihuahuan Desert of trans-Pecos Texas and across the Rio Grande in Mexico, with most collections from the Big Bend area.