Rhododendron albiflorum Hook.

A deciduous shrub 5 or 6 ft high in the wild, the young shoots furnished with short, dark hairs. Leaves narrowly oval, 1 to 21⁄2 in. long, 1⁄2 to 3⁄4 in. wide, tapering towards both ends, thin and glabrous except that, like the very short stalk, they are furnished when young on the midrib with hairs similar to those on the stems. Flowers creamy white, 3⁄4 in. wide, drooping, produced singly or in pairs from lateral buds on the growth of the previous year during June and July, when the young shoots are in full leaf. Corolla open bell-shaped, with five short, rounded lobes. Calyx 1⁄3 in. long, green, the lobes ovate and edged with glands. Stamens ten, shorter than the corolla, hairy at the base; flower-stalk 1⁄3 in. long, glandular-downy. Bot. Mag., t. 3670. (s. Albiflorum)

Native of western N. America from Oregon to British Columbia, forming impenetrable thickets just above the tree-line and along streams. It is a pretty species, very distinct because of the large calyx, the axillary flowers, and the dark hairs on the young wood like those of an azalea of the Obtusum subseries, only not so numerous and persistent. It is not an easy plant to satisfy, but Andrew Harley succeeded with it in his garden in Perthshire, where it was planted in a fairly sunny position and a rather poor, stony soil (New Fl. and Sylv., Vol. 9 (1937), p. 128).