When you think of legumes, you may envision peas, beans or peanuts. These garden staples aren't the only members of the legume family. Some trees are also legumes. These trees have seedpods resembling peas. Like peas and beans, all tree legumes are nitrogen fixers. Trees in the legume family are valuable because they're use atmospheric nitrogen and have deep roots, making them excellent pioneer trees in harsh areas.
The locust is a striking tree with fine, feathery foliage. Native to the Eastern U.S., locusts are prized for their heavy, decay-resistant timber. This hardy species is also an excellent urban tree because it thrives in poor soil. It is often planted near sidewalks and parking lots, because it is resistant to salt that may be applied during the winter in cold climates. Locust flowers are fragrant and appear in late spring and early summer. These flowers develop into elongated pods in some varieties, although seedless varieties of the locust are available.
The redbud is one of the earliest flowering trees. A common ornamental, the redbud is a relatively small tree that grows throughout the Eastern U.S. and as far west as Texas and Kansas. It is at home either in the sun or in partial shade. Most varieties have blooms that are purplish pink, but a white variety is available. Plant this tree as a single specimen tree or in a group. Both the flowers and the pods of this tree are edible. The flowers are used as garnish or blended into pancakes. Pick the pods when young and tender and prepare them with butter like snow peas.
The silk tree, or mimosa, is on the Plant Conservation Alliance's Least Wanted list. This medium-sized tree was imported for its ornamental flowers. However, it is now a pest in many Southern states. The pods are 6 inches long and filled with seeds that stay viable for years. Wetland areas are particularly vulnerable to infestations, as the pods and seeds float downstream. Although this tree is still available in garden centers, homeowners should consider planting noninvasive redbuds or serviceberries instead.
The American yellowwood is a medium-sized tree with profuse, strongly scented blooms. It is native to areas in Kentucky, Tennessee, Arkansas and Missouri with scattered populations in a few other states. This tree is rarely planted in yards because it is slow growing and it may take 10 years to produce flowers. Its flowers are usually white, but a pink-flowered variety is available. This legume produces long, beanlike pods that often persist into the winter. The dried pods and smooth gray bark make this tree attractive \ during the winter months.
- National Park Service: Silk Tree
- The Gateway Gardener; Flowering Trees; Barbara Perry Lawton; March1, 2011
- The Overstory Agroforestry Tree Journal; Nitrogen Fixing Trees--A Brief Introduction; Craig Elevitch, et al
- Kew Royal Botanic Gardens: Black Locust tree (or false acacia), Robinia pseudoacacia
- Great Plains Nature Center: Redbud
- Tree Trail: American Yellowwood
- International Legume Database & Information Service