American yellowwood (Cladrastis kentukea) is a medium to large deciduous tree . The tree is often multi-trunked or low-branched, with a broad rounded crown of angular, thick-jointed twigs. Leaves are compound and each consist of 5-11 oval pale green or bluish leaflets with the entire leaf being about 10” long. Leaves become yellow to gold in fall and leafstalks often persist through winter. Twigs are stout and zigzag with small, hairy, naked buds covered by the leafstalks. Flowers are white hanging in clusters and appear in late spring after leaves. Tree produces flowers greatest in alternative years. Fruit is a flattened green pod that turns brown in fall and sometimes persist into winter. Bark is thin, smooth, pale gray, and lichens and mosses may be present. Native to the southeastern United States, yellowwood is endangered in the wild, but common in cultivation. Named Cladrastis lutea in 1813 (from Latin, luteus, meaning yellow). The genus name Cladrastis comes from the Greek words klados meaning “branch” and thaustos meaning “fragile” for the brittle twigs. In 1971 the species name reverted back to a slightly older and perhaps less fitting Cladrastis kentukea, first used in 1811. The wood produces a yellow dye, therefore the common name yellowwood. The wood has been used to make gunstocks and furniture. Bees find the flowers very attractive. Introduced to Europe in 1812.
Common name: American Yellowwood, Yellow Wood, Yellow Ash, Yellow Locust
Scientific Name (family and order): Cladrastis kentukea (Dum. Cours.) Rudd (1971) (Fabaceae, Fabales) Notable synonyms include Cladrastis lutea (Michx.) K. Koch, Cladrastris fragrans Raf., Sophora kentukea Dum. Cours. Virgilia kentuckensis Raf., Virgilia lutea Michx.
Species Origin: S.E United States
New Jersey Status: USDA Unreported
Habit: 30 – 50’ tall; often multi-trunked or low-branched, broadly spreading.
Habitat: Zones 4 -8; rich woods and rocky bluffs, riverbanks on limestone.
Trunk/Stem: The bark is gray, smooth like beech, BUT it is often covered by lichen and mosses – unlike beech. Twigs are Irregularly tapered
Leaves: Deciduous, Pinnately Compound, Alternate. Pinnately compound made of 7 – 11 alternately placed, elliptic to ovate untoothed leaflets each 2 -3 “ long with acute to acuminate tip, elliptical base; venaion is pinnate; the terminal leaflet is the largest. The leaves are bright green above and smooth on both sides turning bright yellow in autumn. The petiole is swollen at the base (pulvinus) and encloses the bud. Leaf shoots often persist during the winter.
Flowers: Perfect. Pea-like, 1 ¼” long, white, 5 – petals, slightly fragrant, in large hanging terminal panicles 18” long occurring at the end of the shoots in late spring – early summer (like Wisteria).
Fruits and seeds: The fruit is a flattened brown pod, 4” long containing 2 -6 dark brown seeds. Seed pods persist into the winter at the twig tips.