The Kentucky yellow wood is a species of the pea family (Fabaceae) and comes from eastern North America, where it is a threatened species in splintered areas mainly in the Appalachian Mountains. It is at its showiest when it flowers in July, with clusters of large, drooping, strongly scented blossoms. Flowering usually takes place every second year.
This tree has many other attractive features. The leaves are bright green and made up of alternate leaflets, a good recognition feature; in autumn they take on a warm yellow colour. The trunk is pale grey and smooth like the beech. The timber is highly valued for its hardness and beautiful yellow colour.
The Kentucky yellow wood is rarely cultivated in Europe but has grown successfully in the south of Finland, including Mustila since the 1930s. When young, the plants are winter tender, growing rapidly and not always having time to harden off before winter. When they are above 1 metre tall hardiness improves, though spring frosts can damage the foliage even of large trees. So it should not be planted in low-lying or cold spots, but preferably in the protection of other trees or buildings, not only because of frost but also because of wind, which tends to tear off the sharp-angled branches.
A pink-flowered variety called ’Perkins Pink’ is also available, though even more difficult to find than the ordinary white species.