Robinia boyntonii Ashe

A deciduous shrub up to 10 ft high; young shoots unarmed, glabrous or very finely downy. Leaves 6 to 10 in. long, consisting of seven to thirteen leaflets which are oblong, blunt or pointed, 1 to 2 in. long, 1⁄2 to 1 in. wide, glabrous or soon becoming so. Flowers six to twelve together in loose racemes 21⁄2 to 31⁄2 in. long, produced from the lower leaf-axils of the young shoots in May and June, each flower barely 1 in. long; standard petal 3⁄4 to 1 in. wide; calyx 1⁄4 in. wide, bristly. The colour is described by Ashe as ‘rose-purple, pink, or purple and pink on the outer portion, white or much paler at the base’. Pods glandular-bristly.

Native of the E. United States from N. Carolina and Tennessee to Georgia and Alabama. It may have been introduced long ago and grown under the name “R. hispida rosea”, but the plant definitely named R. boyntonii by Ashe reached Kew in 1919. It is, however, not in cultivation at Kew at present. Ashe separates it from true R. hispida ‘by its greater size, more oblong leaflets, many-flowered racemes, short calyx-lobes and smoothness’. The young shoots of that species are, of course, very bristly.