Alnus oblongifolia

Common Names

Arizona Alder, Alder, Oblong Leaf Alder

Summary

Arizona alder is a tall, straight-trunked tree with an open, rounded crown. Bark is smooth and light gray when young, darkening and corking with age; leaves are narrowly ovate to lanceolate (3–11 × 2–7 cm) with a long to short acuminate apex, cuneate or rounded base, and sharply to coarsely double-serrate margins, sometimes with a resin coating and hairy domatia. Flowers are wind-pollinated, with yellow-green male catkins and small cone-shaped female inflorescences; fruits are woody infructescences bearing many winged seeds that ripen to reddish-brown and persist through winter. The tree grows in riparian and mesophytic habitats in the southwestern United States (Arizona, New Mexico) and northern Mexico at elevations of 1,000–2,300 m; it is drought-tolerant, hardy to USDA zone 7, and forms a nitrogen-fixing symbiosis with Frankia in root nodules, aiding soil nitrification and erosion control.

In cultivation, Arizona alder is rare but attractive, and tolerant of drought while easy to grow from seed. It forms groves and colonies in wetland habitats and acts as a fast-growing pioneer that stabilizes riparian zones, with its root system enriching soil and reducing erosion.

Lifecycle

Perennial

Height

60-98 feet

Hardiness Zones

Zones 7-7

Soil Type

Moist, riparian soils.

Soil Drainage

Moist to wet soils, with both well-drained and poorly drained conditions.

Bloom Color

Yellow-green, reddish-green

Bloom Time

Spring

Foliage Color

Dark green on the upper surface with paler green underneath

Leaf Lifecycle

Deciduous

Growth Rate

Rapid growth

Seasons of Interest

Spring, Summer, Fall, Winter

Propagation Methods

Seeds

Attracts Wildlife

Attracts bees, butterflies