Acaciella angustissima aka Prairie Acacia

Acaciella angustissima is a shrub or small tree in Fabaceae. Common names include fernleaf acacia, timbre, and prairie acacia. Older sources use the name Acacia angustissima. Its native range spans the central and southern United States. It extends south to northwestern Argentina. It grows on hillsides, rocky slopes, and summits. It also grows in grassland, open woodland, and pine-oak forest. Some plants grow in hedges. The species varies a lot in form.

This evergreen plant grows fast and has no thorns. Its crown is round. Most plants stand about 7–10 feet [2–3 metres] tall. Garden sources give heights up to 16 feet [5 metres]. Some tree forms reach 23 feet [7 metres] or more. These taller plants can have a single short trunk. One garden source gives a spread of 10 feet [3 metres]. Sources say its bark tastes bitter and has an astringent effect. This means it makes tissues tighten. The pods grow tough as they mature.

Fernleaf acacia grows best in full sun. It cannot grow in shade. It suits warm temperate, subtropical, and tropical climates. It can cope with some brief spells below freezing. Plants For A Future lists USDA zones 7–10. Give it soil that drains well. It grows in sand, loam, and clay, including poor soils. It does well in acid soil. It also copes with soil that is slightly alkaline. It accepts dry or moist ground and copes with drought.

People grow it for its looks and to restore land. It fixes nitrogen and can help trees take root on damaged ground. Growers also use it as a nurse crop for other trees. Its cut growth makes mulch but takes time to break down. Compounds in these cuttings can leave less nitrogen for nearby crops. Sources flag a risk that it may become a weed. They do not say how severe this risk is. Growers can soak seeds in cold water before sowing. Seedlings moved to the site may take root better. This compares with seeds sown in place.

Local people have used the pods as food. Reports say cooked young green pods are edible, not mature pods. There is little evidence for this food use. In Mexico, people use the bark to make fermented drinks. People also use this plant in traditional medicine. They use it for diarrhoea and other ailments. These reports do not prove that such treatments are safe. Nor do they prove that the treatments work.