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Mimosa (Silk Tree)

Albizia julibrissin
Family: 
Fabaceae (beans)
Description: 

A small tree with widely spreading branches, a short trunk and a broad, flat-topped crown.

Leaves alternate, twice-pinnately compound (fernlike), 6–20 inches long, the pinnae (first division) branches 2–6 inches long, the leaflets about 1/2 inch long, lacking teeth but with hairs along the edges. Leaves emerge in spring.

Bark smooth, tight, blotched gray and sometimes brownish on young growth; pores large and conspicuous.

Twigs moderately stout, green to brown or gray, somewhat fluted below nodes (where leaves attach), often zigzag, smooth; pores small, numerous.

Flowers May–August (after leaves emerge), on tips of branches, pink, crowded in tassel-like round heads, 1 1/2 inches across; fragrance is strong and sweet.

Fruits August–September; pods are flat, linear, yellowish-brown, 5–8 inches long, forming large clusters; seeds are flat, light brown, oval, about 1/2 inch long.

Size: 
Height: to 40 feet.
Habitat and conservation: 
Invades disturbed areas along roadsides, edges of woods, old fields and open vacant lots. Also grown in landscape plantings. Mimosa is planted for its fluffy pink summer flowers. A prolific seed producer; the seedlings often become weedy. In northern areas, twigs and branches may be killed by winter cold. Sometimes entire trees die back to the ground. A vascular disease, mimosa wilt, can kill trees. Several insect pests, such as mimosa webworm, can ruin its ornamental value in summer.
Distribution in Missouri: 
Statewide.
Status: 
Native to Asia, mimosa was introduced to our country as an ornamental tree in 1745. It escapes from landscape plantings and becomes weedy and invasive everywhere that winter cold doesn't kill it. It generally does not survive in northern states. It reseeds itself and becomes weedy as far north as Central Missouri. Planting this species is discouraged.
Human connections: 
The pink pompoms of the flowers and fernlike foliage make this seem attractive as an ornamental, but mimosa has a short lifespan, has weak, brittle wood, is susceptible to a host of diseases, insects and poor weather. It resprouts if cut or top-killed and its seeds readily sprout where unwanted.
Ecosystem connections: 
Mimosa is not significant to any native wildlife species, although several insects, such as mimosa webworm, eat the plant.
Shortened URL
http://mdc.mo.gov/node/7073