The mimosa tree (Albizia julibrissin), came to the United States in 1745 as an ornamental species. The mimosa tree's many attractive qualities belie the fact that it is potentially invasive in nature. Once the mimosa tree escapes cultivation and its seeds begin to grow in the wild, the tree can adversely affect the ecosystem. While the mimosa is still popular as an ornamental landscaping species, states such as Florida classify it as an invasive plant.
Silk tree is a common nickname for the mimosa and is a reference to the flowers, which the Floridata website describes as being like "silky powder puffs." The canopy of branches is much like an umbrella, with the limbs arching out from the trunk. The tree will develop multiple trunks in many instances. The National Audubon Society Field Guide to Trees says the bark of mimosa is smooth and grayish to black in color.
The mimosa typically grows between 20 and 40 feet tall. The leaves are compound, with a middle stem as long as 20 inches on which as many as 60 leaflets exist. The pink flowers emerge in clusters as wide as 6 inches and are very fragrant. The flowers then turn into 4- to 8-inch seed pods.
The range of the mimosa tree in the United States now stretches from New Jersey into Florida. According to the Plant Conservation Alliance Alien Plant Working Group website, mimosa is a naturalized species in Georgia, the Carolinas, Kentucky, Tennessee, West Virginia and Louisiana. Mimosa trees originated in Japan and China, and their natural range extends across much of Asia. In the American wild, mimosa often grows along roadsides, in vacant lots and along waterways, where it forms dense thickets.
The mimosa tree as an ornamental is a tree that makes a good fit close up to your home. The mimosa will not grow too tall. The leaves have a design that essentially makes them resistant to high winds, thereby making it difficult for breezes to break off branches onto your roof. The tree sheds its leaves before winter, which will allow sunlight to reach your windows.
Mimosa trees possess distinct advantages over native species, making them a potential problem once growing in the wild. Mimosa will grow in nearly every soil type. The tree will produce huge numbers of seeds, which will then sprout in the area around the original specimen. Mimosa has the ability to grow as much as 3 feet in a single year. Mimosa can live through droughts and exist in the shade of other trees. Once a mimosa becomes established, it can prevent sunlight from helping native plants thrive and will take nutrients from the soil.