American Yellowwood

SCIENTIFIC NAME: Cladrastis kentukea

FAMILY: Fabaceae

This Tree in Colorado: Can be planted for street trees if property pruned to avoid weak crotches (bad branch angles). Is planted as a specimen or shade tree on smaller properties due to its flowers and medium size. Originated in the southeastern United States.

Hardiness: Zones 4 to 8

Growth habit: A deciduous small to medium sized tree, 30-40 feet tall. Develops a broad, rounded crown with branches that are upright and spreading, up to 40-50 feet. The main trunk is usually short with major branches starting within 6 feet of the ground.

Foliage: Alternate, pinnately compound leaves with 7-9 leaflets per leaf. Leaflets are elliptic to ovate and 2-4 inches long. The leaf is between 8-12 inches long. The terminal leaflet is the largest. Color is bright green, turning yellow/gold/orange in the fall.

Flowers: Color is White, pea-like. They are fragrant and individual flowers are apprx. 1 inch and grow in 10-16 inch long clusters. Very showy. Bloom in June and flowers heavily every 2-3 years, however may not start flowering until 10 years old. Bees frequent the flower for nectar.

Fruit: Grey-green pods turning brown in October, 2.5-4 inches long and 0.5 inch wide. Pod contains 4-6 flat, brown, hard-coated seeds. Does not attract wildlife but pod does persist through the winter.

Bark: Thin, gray to light brown. Resembling bark of beech trees. Remains smooth into old age and is considered attractive.

Twigs: Slender, more or less zig-zag, smooth, bright reddish brown, often bloomy, odor and taste resembling that of a raw pea or bean.

Wood: Tree name Yellowwood is from the color of the heartwood, which has a yellow cast to it.

Insects and diseases: Very few problems are associated with this tree. Verticillium wilt has been reported.

Landscape value: Excellent tree for flowers and foliage; the medium size and spreading habit make it a choice shade tree for smaller properties. It can be used as a single specimen or in groupings. Tolerates high pH soils as well as acid situations. LIkes moist, fertile, well-drained soils. Native on limestone cliffs and ridges. Prefers full sun but should be protected from winter sun and wind. Prune only in summer as tree bleeds profusely if pruned in winter or spring.

Cultivars: 'Rosea' ('aka 'Perkin's Pink') -- A special, rare pink-flowered form found in Watertown, MA and offered by numerous specialty nurseries.

Interesting Features: Should be pruned when young to develop branches with wide angles with the trunk and a 'U' shaped crotch. Branch size should be maintained at no larger than half the diameter of the trunk. If form is not shaped watch for bad crotches (narrow branch angles) which may split or crack in storms. All pruning should be done in the summer because of excess bleeding may occur in done in winter or spring.

Information sources: Michael Dirr, Manual of Woody Landscape Plants (University of Georgia, 1990)University of Flordia, IFAS Extension, Publication #ENH329 (http://edis.ifas.ufl.edu)

Photo by Caroline Beal