1. Black Cottonwood – Populus balsamifera ssp. trichocarpa
(POP-you-lus ball-sam-IF-er-a TRY-ko-kar-puh)
Family: Salicaceae (Willow Family)
Native to: Much of western Northern America from AK to Baja; in S. CA in protected valleys and
canyon bottoms, along stream banks, and edges of ponds and meadows, typically in sandy soils.
Woody tree
mature height: 100+ ft.
mature width: 35+ ft.
Large tree with open crown. Trunk of mature trees is thick, covered with furrowed gray bark.
Winter-deciduous. Fast growth rate, particularly when young. Moderate lifespan (< 75 years)
although may live to 150-200 years. Extensive and invasive roots – can damage pipes, drainage
systems & foundations (plant 40 ft from buildings).
Growth characteristics:
Blooms in early spring. Flowers on drooping branches (catkins).
(separate male & female trees). Fruit is a dry pod which splits releasing fluffy seeds.
Blooms/fruits:
Dioecious
Uses in the garden: Most often used for shelterbelts & windbreaks. Also makes good shade tree on
large sites. Does fine with deep summer water and near streams/ponds. Nice scent and fall leaf
color (yellow). Takes up excess nitrogen from soils. May be slightly allelopathic (toxic to other
plants); also, dense shade from spring through fall may limit plantings beneath these trees.
Sensible substitute for: Non-native poplars; other large non-native shade trees.
Excellent bird habitat: provides cover, nesting sites and nectar/buds for food. Important
early source of pollen & nectar for native pollinators and other insects. Larval food source for
several native butterflies.
Attracts:
Requirements:
Element
Sun
Soil
Water
Fertilizer
Other
Requirement
Full sun best; may tolerate very light shade
Any except alkali
Regular deep watering; shallow watering=shallow roots. Tol. seasonal flooding.
Does best with light fertilizer (every few years) or organic mulch; fine with none
Prone to fungal diseases and damage from poplar and willow wood borers; let soil
dry out at least yearly to prevent fungal rots.
Most important is to locate this tree away from waterlines and structures. Also, not
good under power-lines due to height. Prune diseased and weak limbs to prevent wind breakage.
Management:
Propagation: from seed: short viability; plant fresh seeds, spring
by cuttings: when dormant
Plant/seed sources (see list for source numbers): 1, 3, 7, 8, 11, 13, 14, 20
12/9/10
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