Mimosa trees (Albizia julibrissin) are known for their hardiness and their graceful, silky, fragrant flowers. The latter characteristic has given rise to the nickname "silk tree." Mimosa trees are so hardy, in fact, that they are classified as an invasive plant in many states, including Florida. Still, many home gardeners cultivate these fast-growing, small ornamental trees, often planting them in containers to control their spread. There are several cultivars, or types, of the silk tree.
The Rosea cultivar is bushier and shorter--only 10 to 15 feet tall--than most other mimosa cultivars. It was bred to survive drier conditions than the species normally requires, is very cold hardy and tends to live longer than many of the other types of mimosa trees. The bright red flowers of Rosea (sometimes called Ernest Wilson) are very attractive. Rosea is a popular choice for planting in containers.
This cultivar is known for its bright pink, showy flowers and the fact that it is easily obtainable in most nurseries. This tree averages 25 feet in height and is most often used as an accent plant.
Alba is an unusual cultivar of the mimosa tree in that it has creamy white flowers. The tree is much like the Rubra, but lacking red pigments. Like all mimosas, Alba has weak wood and can be easily damaged by ice, wind or both.
Charlotte is a cultivar that is resistant to mimosa wilt, a devastating disease that can quickly kill any mimosa tree. This rare cultivar is not easy to find. Summer Chocolate is an unusual cultivar that features dark, burgundy foliage rather than the bright green of most cultivars. Umbrella is a large mimosa cultivar that can grow up to 40 feet tall and has an umbrella-shaped canopy. This type of mimosa is also cold-hardy. Pendula is a small type of mimosa. The tree only reaches 10 feet tall at its maximum height and has a strong weeping habit.