Bill Johnson

Silk Tree

Albizia julibrissin Durazz.
Pea family (Fabaceae)

Origin: Asia

Background
Silk tree, also called silky acacia or mimosa tree, was introduced to the United States in 1745 for use as an ornamental plant.

Distribution and Habitat
Silk tree occurs from California across the southern United States to New York. It grows in disturbed areas such as roadsides, forest edges and various open habitats. It is a hardy plant that tolerates a variety of soil and moisture conditions, enhanced by the ability of its roots to produce nitrogen.

Ecological Threat
Silk tree grows vigorously and displaces native trees and shrubs, spreading by seed and vegetative means. Once established, silk tree is difficult to remove due to its long-lived seeds and its ability to re-sprout vigorously.

Description and Biology

• Plant: small deciduous tree that grows 10-50 ft. in height and often has multiple trunks; the bark is light brown, nearly smooth, thin and has lens-shaped spots along the stem.
• Leaves: alternate, twice-pinnately compound, fern-like.
• Flowers, fruits and seeds: flowers are pink, fragrant and look like pom-poms; flowering occurs in early summer; fruits are flat 6 in. long seedpods that develop in the late summer.
• Spreads: by seed and vegetative growth.
• Look-alikes: honey locust (Gleditsia triacanthos) and black locust (Robinia pseudoacacia) with leaves that are once-pinnately compound.

Prevention and Control
Do not plant silk tree. Trees can be cut at ground level with power or manual saws. Cutting is an initial control measure, best done prior to seed set, and usually requires follow-up cuttings in combination with herbicide treatments due to re-sprouts. Systemic herbicides like glyphosate and triclopyr are effective (see Control Options).

Native Alternatives
Serviceberry (Amelanchier arborea), river birch (Betula nigra), redbud (Cercis canadensis), fringetree (Chionanthus virginicus) and flowering dogwood (Cornus florida).