Black Locust vs Mountain Alder - TreeTime.ca

Black Locust vs Mountain Alder

Robinia pseudoacacia

Alnus incana subsp. tenuifolia

CUSTOM GROW

Black Locust
Mountain Alder

Black Locust is an attractive tree. Its distinctive leaves are made of about a dozen bright green leaflets. It also notable for its fragrant white flowers, which smell of citrus.

Black Locust can grow in many situations, but prefers dry areas with lots of sun. It is robust and is an excellent choice for establishing shade in dry, open areas.

Important note: Much of the Black Locust is toxic to humans and livestock, including seeds, bark, and leaves.

Mountain Alder is a native cold-hardy shrub or small tree often found along streams and in moist forested habitats. Its nitrogen-fixing ability enriches soils and supports surrounding vegetation, while its extensive root system helps stabilize streambanks and slopes. The fast growth rate allows it to establish quickly on disturbed sites, making it especially valuable in reclamation, restoration, and erosion control projects.

Often forming dense thickets, Mountain Alder enhances habitat quality in riparian and upland areas. It provides food and cover for various wildlife, including birds and small mammals. Recognized as an important species for soil and water conservation, it is well suited for riparian planting, naturalization, and ecological restoration.

Note: We use Sitka Alder for Alnus incana subsp. tenuifolia. This species is also known by many other common names, including Grey Alder, River Alder, and others. Please confirm the scientific name to ensure you are ordering the correct plant.

Black Locust Quick Facts

Mountain Alder Quick Facts

Lowest Price: $9.99
Zone: 3a
Zone: 1a
Height: 12 m (40 ft)
Height: 6 m (20 ft)
Spread: 8 m (25 ft)
Spread: 3 m (10 ft)
Light: full sun
Light: partial shade, full sun
Moisture: dry, normal
Moisture: normal, wet
Growth rate: fast
Growth rate: medium
Life span: long
Life span: medium
Growth form: multi-stemmed, thicket-forming
Spreading: rhizomes - medium, seeds - low, layering - low
Suckering: high


Bark: dark reddish brown to balck with furrows
Bark: smooth, gray to brown
Flowers: Creamy white flowers in a pyramidal shape bloom in may-june
Seeds: dark brown peapod-like pods
Hybrid: no
Hybrid: no
Catkins: no
Catkins: yes


Native to: AB, BC, SK, YT, NT
Other Names: false acacia, yellow locust
Other Names: river alder, speckled alder, thin-leaved alder, thinleaf alder, western river alder