Prosopis torquata

Name and classification

Prosopis torquata (Cav. ex Lagasca) DC.
Family Fabaceae, Subfamily Mimosoideae

NOTE: Only four seeds of Prosopis torquata 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 moniliform, with one margin straight, the other deeply undulate, causing 1–3 irregular, open coils forming a loose spiral that is ca. 2.5–7 cm long; compressed, rounded articles each 5–8 mm long and wide, ca. 2–3 mm thick, with off-center isthmi 2–5 mm wide. Short-stipitate, light reddish-brown when ripe, wrinkled. 8–13 articles per pod. Endocarp segments hard and boney, closed, disclike, 5–7 mm long, x 4.5–6 mm wide, 3–4 mm thick; mesocarp tannic-reddish, pulpy. Seeds oriented longitudinally.

Seeds obovate to broadly elliptic in outline, 4–5.2 mm long, 2–3.6 mm wide, 2–2.5 mm thick, with a very prominent umbo, subrhombic in cross section. Pleurogram small, open, distinctly basal. Lens a dull mound.

Identification considerations

The spiral pods are distinctive in the genus. The seeds have an unusually small pleurogram, and a very prominent umbo.

Distribution

Argentina

Habitat

mountainous semi-desert

General information

Prosopis torquata is a spiny, erect or spreading shrub or small tree 1–5 m tall. Its wood is heavy and dense, making it a good firewood. In the past it was used for steam locomotives and is still used for cooking and heating. The seeds are completely enclosed in the hard, closed endocarp segments.

seeds

seeds

seed with pleurogram visible

seed with pleurogram visible

seeds

seeds

lens and hilum of seed

lens and hilum of seed

pods

pods

pod

pod

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

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