Vachellia pennatula

Tilcayo Cats original · Plants · Sources and editorial assessment · Originals retention rule

Vachellia pennatula is a shrub or tree in the pea family, Fabaceae, native from Mexico through parts of Central America to northern and western South America, including Venezuela and Peru. It grows primarily in seasonally dry tropical vegetation. Older literature often uses the name Acacia pennatula.

Appearance

A northeastern Mexican treatment describes trees up to nine metres tall, with slender paired spines. The leaves are finely divided: numerous pairs of side branches each bear many pairs of tiny leaflets. The treatment distinguishes this plant from other local Vachellia species by its combination of slender spines and numerous leaf divisions.

Flowers are grouped in spherical heads. The brown pods are straight or gently curved, roughly five to thirteen centimetres long, and remain closed at maturity. This regional description should not be read as a complete account of variation across the species' extensive range. Kew recognises two varieties, pennatula and parvicephala.

Habitat and uses

The Mexican review records the species in disturbed habitats and describes it as rare in Tamaulipas, within the northeastern region covered by that study. Its hard wood is used for construction, fence posts, tool handles, fuel and other woodwork. The foliage is used as livestock forage.

Leaf litter and nutrient cycling

A study in pastures in Veracruz, Mexico, examined fallen leaves of this species and Lysiloma acapulcense. Researchers placed litter in bags beneath the trees and followed decomposition for thirty-two weeks. The amount remaining at the end was similar across the four combinations of leaf species and tree shade tested.

Decomposition was relatively slow in those warm, seasonally moist conditions. Nitrogen and phosphorus accumulated in the litter during the experiment, which the researchers interpreted as possible retention by associated microorganisms. These local results describe one stage of nutrient cycling; they do not establish the same decomposition rate in every habitat.