Spiraea arcuata Hook. f.

A medium-sized shrub with arching, strongly ribbed reddish brown stems, which are finely woolly when young, more or less glabrous by autumn. Buds hairy, slender, acute, longer than the petioles. Leaves dark green, shortly stalked, those on the strong shoots obovate or obovate-elliptic, to about 1⁄2 in. long, mostly crenately toothed or lobulate at the apex, on weaker shoots smaller and mostly entire; they are glabrous with somewhat impressed main veins above, undersides glabrous except for hairs on the prominent veins, margins with a woolly ciliation. Flowers typically pink but sometimes white, borne in early summer in dense or lax umbel-like or compound clusters up to about 11⁄2 in. wide, terminating short leafy laterals. Peduncles finely woolly, each furnished with a bract, which is leaf-like in the outer part of the inflorescence. Receptacle shallow, glabrous. Follicles well exserted, glabrous and lustrous; styles inserted below the apex, outward-pointing.

Native of the Himalaya from Nepal (perhaps farther west) to S.W. China, and of S. Tibet. An ornamental and unusual spiraea, perhaps allied to S. gemmata, though differing from it in foliage. It is still rare in gardens.