Alnus acuminata aka Andean Alder

Alnus acuminata is an evergreen alder in the birch family. Its native range runs from Mexico to northern Argentina. It grows in tropical mountains, often on steep slopes. It forms dense stands or grows with oaks and pines. Some sites have a dry season lasting three to five months. Useful Tropical Plants reports a Least Concern assessment from 2011. It also notes past habitat loss in dry Andean valleys.

This fast-growing tree has a broad, rounded crown. Its usual height is 33–82 feet [10–25 metres]. PFAF gives a spread of 82 feet [25 metres]. Exceptional trees reach 98–131 feet [30–40 metres] tall. Poor sites may limit growth to a shrub. The trunk is straight and often supports a wide crown. The leaves stay on the tree through the year. Male and female flowers form catkins; the female catkins are small. Wind carries the pollen, and older seed cones remain visible.

Choose a sunny site for the best growth. The tree also tolerates light shade. It prefers moist soil that drains well. Sand, loam, and clay can all support growth. It tolerates poor soil and a broad pH range. These include very acid soils and mildly alkaline ground. The tree fixes nitrogen, which adds to its soil value. PFAF lists USDA zones 10–12 for this species. Plants can endure brief dips below freezing. Their best growth occurs in warm conditions with ample rain.

People plant this alder for timber and to restore bare land. Its fast growth helps it establish on open sites. Plantings help limit erosion and improve soil on damaged ground. Farmers also use it for crop shade and living supports. It suits highland reforestation work in the tropics. People harvest its wood for fuel and charcoal. The tree also supplies tannins and dyes. It can regrow under coppice management, which supports repeated harvests.

PFAF lists no known food uses for this alder. It records no known hazards, but this does not prove safety. Bark and leaves have a history of medicinal use. These uses include treatments for sore joints, muscle pain, and skin infections. Such records do not establish that a treatment works. Fresh seed needs prompt sowing because it loses viability quickly. PFAF describes a short cold treatment before sowing. Seedlings grow fast and can reach planting size within weeks.