Cladrastis kentukea

Cladrastis kentukea is a small to medium-sized deciduous tree typically growing tall, exceptionally to tall, with a broad, rounded crown and smooth gray bark. The leaves are compound pinnate, long, with 5-11 (mostly 7-9) alternately arranged leaflets; each leaflet broad ovate with an acute apex; long and broad, with an entire margin and a thinly to densely hairy underside. In the fall, the leaves turn a mix of yellow, gold, and orange. The flowers are fragrant, white, produced in Wisteria-like racemes long. Flowering is in early summer (June in its native region), and is variable from year to year, with heavy flowering every second or third year. The fruit is a pod long, containing 2-6 seeds. • Bark: Smooth gray, or light brown. Branchlets at first downy, but soon become smooth, light yellowish green; later red brown, finally dark brown. • Wood: Yellow to pale brown; heavy, hard, close-grained and strong. Sp. gr., 0.6278; weight of cu. ft., . • Winter buds: Four in a group, making a tiny cone and enclosed in the hollow base of the petiole. • Leaves: Alternate, pinnately compound, long, main stem stout, enlarged at base. Leaflets seven to eleven, broadly oval, long. Wedge-shaped at base, entire, acute, terminal leaflets rhomboid-ovate. Feather-veined, midrib and primary veins prominent, grooved above, light yellow beneath. They come out the bud pale green, downy; when full grown are dark green above, pale beneath. In autumn they turn a bright clear yellow. • Flowers: June. Perfect, papilionaceous, white, borne in drooping terminal panicles long, broad, slightly fragrant. • Calyx: Campanulate, five-lobed, enlarged on the upper side. • Corolla: Papilionaceous; standard broad, white, marked on the inner surface with a pale yellow blotch; wings oblong; keel petals free. • Stamens: Ten, free; filaments thread-like. • Pistil: Ovary superior, linear, bright red, hairy, bearing a long incurved style. • Fruit: Legume, smooth, linear-compressed, tipped with the remnants of the styles. Seeds four to six, dark brown. ==Distribution==

Cladrastis kentukea is one of the rarest trees of eastern North America. It is found principally on the limestone cliffs of Kentucky, Tennessee, and North Carolina. The largest specimen known is at Spring Grove Cemetery in Cincinnati, Ohio, tall and trunk diameter; the tallest known is a slender tree tall but only trunk diameter, at Plott Cove Research Natural Area, Georgia (Spongberg & Ma 1997; Eastern Native Trees Society). Some specimens from Alabama, whose young leaves have especially hairy undersides, have been distinguished as Cladrastis kentukea f. tomentosa (Steyermark) Spongberg. However, this variation is not considered significant. ==Cultivation==

Cladrastis kentukea is widely grown as an ornamental tree for its attractive flowers, and is locally naturalized in many areas of the eastern United States outside of its restricted native range. It thrives in full sunlight and in well-drained soil, tolerates high pH soils as well as acid situations. The Yellowwood can withstand urban settings and is attractive to birds. A number of cultivars have been selected, including 'Perkin's Pink' (syn. 'Rosea', an invalid name) with pink flowers. Kentucky yellowwood is recommended as one of the best medium-sized trees for cultivation as an ornamental plant in gardens. The only quality that is mentioned is a tendency of the trunk to divide very near the ground, as a multi-trunked tree. ==Uses==

The name yellowwood derives from its yellow heartwood, used in small amounts for specialist furniture, gunstocks and decorative woodturning. This plant has been marked as a pollinator plant, supporting and attracting bees and butterflies. ==Distinctions==

Yellowwood won a Pennsylvania Horticultural Society Gold Award in 1994. The Society of Municipal Arborists selected the yellowwood (Cladrastis kentukea or C. lutea) as its Urban Tree of the Year for 2015. ==References==