Alnus rhombifolia

Common Names

White Alder, California Alder, Sierra Alder

Summary

White alder is a fast-growing deciduous tree native to western North America, typically reaching 40–80 ft tall with an open to pyramidal crown and a straight trunk. It features dark green, glossy leaves, slender pendulous branches, greenish-yellow catkins in spring, and persistent brown cone-like fruits; bark is light gray to whitish when young and becomes scaly with age; nitrogen-fixing roots enhance soil fertility and the tree tolerates heat, wind, and a range of moist to wet soils, including heavy clay and alluvial sites, commonly growing along streams and damp habitats.

In cultivation it prefers full sun to partial shade and moist, well-drained to wet soils; propagation is via seed or softwood cuttings; it is used for creek-side erosion control, riparian restoration, streambank stabilization, and wildlife habitat by attracting birds.

Lifecycle

Perennial

Height

50-80 ft

Spread

30-40 feet

Hardiness Zones

Zones 8-11

Sunlight Requirements

Ideally full sun to partial shade.

Soil Type

Moist, well-drained soils including alluvial soils along streams

Soil Drainage

Moist but well-drained

Soil pH

4.0-8.0, tolerates acidic to alkaline soils, no specific ideal pH

Bloom Color

Insignificant

Bloom Time

Spring

Foliage Color

Upper surface green; lower surface yellow-green

Fall Foliage Color

Green

Leaf Lifecycle

Deciduous

Growth Rate

Fast-growing

Seasons of Interest

Spring, Summer, Fall, Winter

Propagation Methods

Seeds, Cuttings, Layering, Sprouts

Attracts Wildlife

Attracts birds and butterflies