Albizia julibrissin

Albizia julibrissin, or Silk Tree, is a member of the Fabaceae (legume) family. It is also known as Mimosa and is a native of Asia that was introduced in the United States in 1745. It was cultivated as an ornamental tree due to its fragrant and showy flowers. This tree is now invasive in North Carolina and other parts of the Southeastern United States. The genus name, Albizia, honors Filippo degli Albizzia, an Italian naturalist, who introduced the Silk Tree to Tuscany, Italy.  The species name, Julibrissin, comes from the Persian word "gul-i brisham" which means silk flower. 

The Silk Tree is a fast-growing, small to medium size, deciduous tree. It typically is found along roadsides, grasslands, vacant lots, clearings, or flood plain areas. The tree has a broad crown and may have single or multiple trunks. Its height typically ranges from 10-50 feet and width spread 20-50 feet.  In 2006 a Silk Tree was found that measured 64 feet high and had a width spread of 80.4 feet. The tree tolerates summer heat, and its flowers prefer full sun.  The limbs of the tree are weak and may be damaged by strong winds, snow, and ice. It is a short-lived tree with an average life span is 30 years. The leaves are fern-like in appearance and are very sensitive. The leaflets will close when touched and at nighttime. It blooms from May to July. The fragrant flowers appear to be pompom-like clusters of silky pink threads and measure about 1.5 inches long.  Bees, butterflies, and hummingbirds are attracted to this flowering tree. The fruits are flattened legumes and contain 5 to 16 seeds. The fruits first appear in June and typically mature from August to September. The seeds are easily dispersed by the wind, water, or by animals.  The seeds contain a neurotoxin when ingested can be toxic to livestock and dogs.

The Silk Tree will take advantage of disturbed land areas.  It grows vigorously and can displace native trees and shrubs. It produces a large number of seeds and it will  resprout when cut back or damaged. It is a strong competitor for native species in open areas, along roadsides and forest edges due to its ability to grow in different soil types and its large production of seeds. When planted near homes, it requires significant clean up from shedding of their leaves, blooms, and seed pods. The tree can tolerate a variety of soils and moisture conditions because its roots have the ability to produce nitrogen. Mimosa can grow in dense stands which reduces sunlight and nutrients that preferred species require. It can also become a problem along banks of waterways, where its seeds are easily transported in water. Due to its invasive nature, the planting of the Silk Tree should be limited. There are many other native, non-invasive trees which would be much better alternatives. 

Diseases, Insects, and Other Plant Problems:

The Silk Tree is susceptible to Mimosa webworms, mites, Vascular Wilt Disease, Shot Hole Borer, Armillaria Fungus, Root Rot,  and a cottony cushion scale.  Wilt may also occur which is caused by a soil-born fungus that affects the root system and will eventually cause the tree to die.