129 Albizia julibrissinCommon Names: silk tree, mimosa Family: Fabaceae (bean Family)
Silk tree is a fast growing, deciduous small tree reaching heights up to 35 ft (10.7 m). The mimosa, as it is also called, has an open, airy, umbrellalike canopy often with multiple trunks. The trunk is smooth and the branches arch gracefully. The leaves are about 1 ft (0.3 m) long, held alternately on the stem and twice compound. Each featherlike leaf has a central rachis (leaf stem) with a dozen or so side branches bearing the 0.5 in (1.3 cm) leaflets. The tiny flowers are pink and arranged in compound clusters about 6 in (15.2 cm) across that look like fluffy silk powder puffs. Their fragrance fills the mid-summer air and attracts honey bees. The flattened seeds are held in pods, 4-8 in (10.2-20.3 cm) long and 1.5 in (3.8 cm) wide. There are several named cultivars differing mainly in flower color.
There are over a hundred species of Albizia, all native to Asia, Africa or Australia. Originally from China, this species, Albizia julibrissia, has been cultivated as an ornamental in the southeastern United States and Europe since the 18th century. In many areas it has escaped cultivation and is now established, growing and reproducing on its own along roadways and other disturbed areas.
CultureThrives in a wide range of soil conditions, including alkaline soils. Light: Best in full sun; tolerates partial shade. Moisture: Drought tolerant. Hardiness: USDA Zones 6 - 9. Withstands total neglect, as evidenced by its naturalization throughout the southeastern U.S. from Washington D.C. to Florida. Propagation: Seed, but the hard seat coat requires scarification before germination can occur. Nick the seed with a file, soak it in sulfuric acid, or plunge it into boiling water.
Silk tree makes a beautiful lawn accent. The graceful, leafy canopy permits enough light for grass to grow right up to the trunk. Often planted (or volunteer seedlings are encouraged) around homes, decks, patios and porches where they provide summertime shade without threatening the roof. Silk tree is susceptible to a fungus blight that attacks older, larger trees and kills them quickly. Fortunately silk trees can grow as fast as 3 ft (0.9 m) per year or more so landscape specimens are quickly replaced.
This is a great tree to grow right next to the house so it can expand over the roof or patio. The open, airy canopy makes silk trees highly wind-resistant, and they never get big enough to cause damage if they should break off. The leaflets fold up at night, allowing heat to escape from the roof or patio. And, all the leaves fall off in winter so the sun can get through.
Silk tree is listed by the Florida Exotic Pest Plant Council as a Category I species, defined as an invasive exotic plant that is disrupting native plant communities. In many parts of Florida and the southeast, silk tree has invaded road shoulders, abandoned fields and (in rare cases) natural habitats. I (SC) think its threat to natural plant communities is overstated.
Steve Christman 5/29/97; Updated 7/05/98, 9/9/00, 5/31/04, 6/15/04, 6/3/06, 3/10/08