Download Albizia julibrissin – Report

Albizia julibrissin is pronounced Al-BIZ-ee-uh joo-lih-BRISS-in. This deciduous tree is a member
of the legume family, the 3rd largest angiosperm family, composed of large flowering plants from
500 genera and over 15,000 species. Fabaceae includes trees, shrubs, herbs, and vines, many
with nitrogen-fixing bacterial root nodules. Legumes prefer semi-arid to arid habitats with this
being related to their nitrogen-demanding metabolism.
Albizia julibrissin is called silk tree, silky acacia
or mimosa tree. According to the National Park
Service it was introduced to US in 1745 as
ornamental plant. Although the spelling is
different, the genus is likely named in honor of
Fillippo delgi Albizzia, an Italian naturalist, who
introduced mimosa to Tuscany, Italy.
This fast growing deciduous tree grows 10’ to
40’ in height and often has multiple trunks. It
has low and wide spreading branches with a
canopy width that can be twice the height of the tree. The pink silk tree prefers full sun and
grows in a variety of soils, but has low salt-tolerance. It grows well in acid or alkaline soil, and is
often found in disturbed areas along roadsides and in open vacant lots.
The delicate leaves are alternate, feathery and fernlike. Attractive pink
flowers have a strong, sweet fragrance and resemble pom-poms. The
blooms are showy from May to July.
The unifying feature of this family is the fruit, a
legume, commonly referred to as a pod. Numerous
yellowish-brown seed pods are produced during
August and September. The yellowish brown pods are
5-8 inches long and flat with 5-10 seeds per pod.
Gums, tannins, oils, resins, medicinal compounds, and dyes are obtained
from plants of this family, along with valuable timber from some species.
Pests, Diseases and Problems
The numerous pods harbor Mimosa webworms. Other invertebrate pests include carpenter
worm, acacia psyllid, root knot nematodes and recently the polyhphagous shot hole borer.
Mimosa (Fusarium) wilt is quite a problem and is fatal. It can spread to adjacent Mimosa trees
by root grafts. Environmental disorders include mineral deficiencies, nutrient and mineral
excesses and poor water management.
The litter problem of the blooms, leaves, and the long seed pods requires consideration when
planting this tree. Also the wood is brittle and has a tendency to break during storms, but usually
the wood is not heavy enough to cause damage. Typically, most of the root system grows from
only two or three large-diameter roots originating at the base of the trunk. These roots can raise
walks and patios as they increase in diameter with the tree being difficult to transplant as its size
increases.
Habitat
The plant, native to Asia, was introduced to the United States about
1745 and now is found in the southern and eastern United States (see
map). Varieties include A. j. rosea, ‘Boubri’, ‘Summer Chocolate’, and
Durazz.
The USDA Forest Service reported that Albizia julibrissin Durazz. is
considered invasive in DC, FL, GA, KY, LA, MA, NC, NJ, SC, TN, VA
and WV, as of December 2004.
In 2009, the National Park Service Plant Conservation Alliance's (NPS PCA) Alien Plant
Working Group described A. julibrissin's ecological impacts as follows:
“Because silk tree can grow in a variety of soils, produce large seed crops, and
re-sprout when damaged; it is a strong competitor to native trees and shrubs in
open areas or forest edges. Dense stands of mimosa severely reduce the
sunlight and nutrients available for other plants.”
According to the National Park Service, despite this status:
"it continues to be a popular ornamental because of its fragrant and showy flowers."
Albizia julibrissin not considered an invasive tree by The California Invasive Plant Council (CalIPC). However, in November 2013, the Contra Costa County UC Master Gardener Program
catalogued this tree in its list of Trees Not Recommended for Planting in Lawns, because it is:
“Invasive, messy leaves, flowers, and pods.”
The City of San Diego has Albizia julibrissin Durazz. listed as an approved street tree species.
Also it is included in Ornamental Trees for Mediterranean Climates the trees of San Diego by
Steve Brigham and published by the San Diego Horticultural Society in 2005.
Ellie Aitken
May 31, 2016