Prosopis humilis

Name and classification

Prosopis humilis Gillies ex Hook. & Arn.
Family Fabaceae, Subfamily Mimosoideae

NOTE: Only one seed of Prosopis humilis was 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, compressed, straight or subfalcate; short-stipitate, apex mucronulate, margins barely undulate; 4–10.5 cm long, 8–12 mm wide. Dull, reddish-brown to dark brown; seed chambers visible, (4)7–16. Endocarp segments subquadrate to rhombic, or broader than long, papery to boney, closed, 6–8 mm long, 8–10 mm wide, 3–4 mm thick; mesocarp thin and dry. Seeds oriented longitudinally.

Seeds asymmetrically obovate to rhombic in outline, 6–7.5 mm long, 4–4.9 mm wide, 2–2.8 mm thick, with an umbo, elliptic in cross section. Pleurogram basal, narrow. Lens a yellowish mound.

Identification considerations

Seeds have an unusual, relatively small pleurogram.

Distribution

Argentina

Habitat

pampas (treeless plains), open semi-xerophytic woodlands, sometimes in rocky or sandy soils

General information

Prosopis humilis is a nearly leafless, spiny, erect to prostrate subshrub, 20–40 cm high. Its peculiar prostrate habit is an oddity. The mesocarp is thin and dry; pods break up into one-seeded segments.

seed

seed

lens and hilum of seed

lens and hilum of seed

pods

pods

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

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