Alnus jorullensis aka Evergreen Alder

Alnus jorullensis, or Mexican alder, belongs to the birch family. Its native range runs from Mexico south to Honduras. It grows beside streams and rivers, in swamps, and on damp mountain slopes. Dense stands can form at middle and high elevations. It also grows in cool mountain forests with ample rain. Some sites have open woods of oak, pine, or fir.

This large tree has an upright or spreading crown. RHS describes trees reaching 82 feet [25 metres]. Useful Tropical Plants gives an upper height of 98 feet [30 metres]. RHS lists a spread beyond 26 feet [8 metres]. Mature trees can have a straight trunk with a long, branch-free section. Sources differ on leaf retention, from deciduous to almost evergreen. RHS says leaves stay through winter, then renew fast in spring. The slim, deep green leaves have teeth spaced along their edges.

Cream male catkins appear in spring, and wind carries the pollen. Small, woody, cone-like female structures form in autumn. The tree suits banks, slopes, screens, and clipped hedges. Growers can also train it above a clear trunk. Its size and branching form give it a strong garden presence. Allow space for a large tree unless maintaining a hedge. RHS gives a maturity period of 20–50 years.

Grow it in full sun and soil that stays damp. It tolerates some shade, but sun gives the best growth. Clay and loam suit it, including soil with poor drainage. It accepts acid, neutral, and alkaline ground. Root microbes fix nitrogen, which helps it grow on poor sites. Nearby plants can share some of that nitrogen. RHS rates its hardiness H5; PFAF lists USDA zones 7–12. Growers can raise it from seed or hardwood cuttings. It also responds well to coppicing.

People plant this alder to restore woodland on disturbed ground. They grow it for timber, fuel, charcoal, and soil improvement. It also helps improve soil fertility in farm planting systems. Possible pests include alder leaf beetle, alder sucker, and leaf-mining sawflies. Phytophthora root rot and honey fungus can also affect it. The sources report no known edible or medicinal uses. They list no known hazards, but do not establish food safety. Useful Tropical Plants reports a 2013 IUCN assessment of Least Concern.