Prosopis alpataco

Name and classification

Prosopis alpataco Phillipi
Family Fabaceae, Subfamily Mimosoideae

NOTE: Very few seeds (less than ten) of Prosopis alpataco were available for examination. Therefore, the description and images in this fact sheet may not be representative of this species’ seeds.

Common names

mesquite

Description

Pods linear, subfalcate or rarely subannular or S-shaped; 7–17 cm long, 6–12 mm wide, ca. 5 mm thick. Short-stipitate, apex short-tapered, margins distinctly undulate (submoniliform), or almost straight. Smooth, straw-yellow, frequently violet-tinged, veins are faint, mostly parallel longitudinal striations; seed chambers 8–18. Endocarp segments subquadrate to ovate, boney, closed, 8–11 mm long, 9–10 mm wide, 4–5 mm thick; mesocarp scarcely pulpy, bitter or sometimes sweet. Seeds oriented longitudinally.

Seeds +/– obovate in outline, 5.5–7 mm long, 2.5–5 mm wide, 2–3 mm thick, with an umbo, elliptic in cross section. Pleurogram average in size. Lens a mound.

Identification considerations

The pod is variable in appearance and often violet-tinged, which is not uncommon in the series Chilensis.

Distribution

Argentina, Chile

Habitat

arid climate

General information

Prosopis alpataco is a spiny shrub, 20 cm – 3 m tall which starts from thick underground horizontal branches. It is somewhat variable in its fruit and foliage, but varieties have not been distinguished. Livestock and wildlife do not eat the bitter pods, so the seeds of P. alpataco are most likely not animal-dispersed.

seeds

seeds

lens and funiculus remnant of seed

lens and funiculus remnant of seed

pods

pods

pods

pods

A, fruit; B, one-seeded endocarp segment; C, seed; D, longitudinal section of seed showing embryo; E, transection of seed; drawing by Lynda E. Chandler

A, fruit; B, one-seeded endocarp segment; C, seed; D, longitudinal section of seed showing embryo; E, transection of seed; drawing by Lynda E. Chandler