Mimosa (Silk Tree)

Illustration of mimosa leaves, flowers, fruit.
Scientific Name
Albizia julibrissin
Fabaceae (beans)

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

Leaves are alternate, twice-pinnately compound (fernlike), 6–20 inches long, the pinnae (first division) branches 2–6 inches long, the leaflets about ½ inch long, lacking teeth but with hairs along the edges. Leaves emerge in spring.

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

Twigs are 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, 1½ 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 ½ inch long.

Height: to 40 feet.
Where To Find
image of Mimosa Silk Tree distribution map
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, and the seedlings sprout like weeds. 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.
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 struggles to survive in far northern states. It reseeds itself and becomes weedy as far north as Central Missouri. Planting this species is discouraged.
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, weak crotches, and 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.
Mimosa is not significant to any native wildlife species, although several insects, such as mimosa webworm, eat the plant. Please plant native ornamental trees instead of mimosa. Try redbud, flowering dogwood, fringe tree, and smoke tree.
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About Trees, Shrubs and Woody Vines in Missouri
There are no sharp dividing lines between trees, shrubs, and woody vines, or even between woody and nonwoody plants. “Wood” is a type of tissue made of cellulose and lignin that many plants develop as they mature — whether they are “woody” or not. Trees are woody plants over 13 feet tall with a single trunk. Shrubs are less than 13 feet tall, with multiple stems. Vines require support or else sprawl over the ground.