Albizia julibrissin, the Persian silk tree, pink silk tree, or mimosa tree, is a species of tree in the Fabaceae family, native to southwestern and eastern Asia.

Taxonomy

It was introduced to Europe in the mid-18th century by Italian nobleman Filippo degli Albizzi, and the name of its entire genus Albizzia is given after him. The specific epithet julibrissin is a corruption of the Persian word (), which means "silk flower" (from "flower" + "silk"). Its bark is dark greenish grey, becoming vertically striped with age. Its leaves are large and frond-like: They are bipinnate, divided into 6–12 pairs of pinnae, each with 20–30 pairs of leaflets. Individual leaflets are oblong, long and broad. The true leaves are long and broad.

thumb|Flowers, parts

thumb|[[Eurema blanda laying eggs on A. julibrissin]]

The flowers bloom throughout the summer in dense inflorescences, which resemble starbursts of pink silky threads. The true flowers have small calyx and corolla (except the central ones), with a tight cluster of prominent stamens, 2–3 cm long and white or pink with a white base. They have been observed to attract bees, butterflies and hummingbirds.

A. julibrissin is widely planted as an ornamental plant in parks and gardens, grown for its fine leaf texture, flowers and attractive horizontal canopy. Other positive attributes are a fast growth rate, low water requirements and the ability to thrive planted in full sun in hot summer climates. It is frequently planted in semi-arid areas like California's Central Valley, central Texas and Oklahoma. Although capable of surviving drought, growth will be stunted and the tree tends to look sickly. As such it should be given infrequent, deep waterings during the summer, which will benefit growth and flowering.

A. julibrissin f. rosea has gained the Royal Horticultural Society's Award of Garden Merit; likewise the cultivar 'Summer Chocolate'.

Other uses

Silk tree wood may be used to make furniture. It is also reportedly psychoactive as well, with the flowers being used to make teas. In Chinese medicine it is considered an antidepressant.

Invasive species

left|thumb|Distribution of A. julibrissin in the United States

thumb|A. julibrissin in Cape May, New Jersey

In the wild, the tree tends to grow in dry plains, sandy valleys, and uplands. It has become an invasive species in the United States, where it has spread from southern New York, New Jersey and Connecticut, west to Missouri and Illinois, and south to Florida and Texas. It is cultivated in California and Oregon. Its seeds are wind-dispersed and numerous, and they are fertile even over long periods of drought. Each pod, which resembles a flattened bean pod made of paper, holds about 8 seeds on average. The pod bursts in strong winds, and the seeds can carry over long distances.

Breeding work is currently underway in the United States to produce ornamental plants which will not set seed and can be planted without risk. However, in the eastern United States it is generally a short-lived tree, being highly susceptible to mimosa vascular wilt, a fungal disease caused by a species of Fusarium, though the disease does not seem to have seriously impacted its populations. Because of its invasive tendencies and disease susceptibility, it is rarely recommended as an ornamental plant in the United States, though it is still widely planted in parts of Europe.

References

  • Albizia julibrissin List of Chemicals (Dr. Duke's Databases)