Spiraea decumbens W. Koch

A dwarf shrub, 3 to 8 in. high, with slender, glabrous, often prostrate stems, from which the thin, wiry flowering branches ascend. Leaves obovate or oval, tapered at both ends, sharply, angularly and rather coarsely toothed towards the apex, 1⁄2 to 11⁄2 in. long, 1⁄4 to 1⁄2 in. wide, quite glabrous on both surfaces; stalk about 1⁄8 in. long. Flowers white, 1⁄4 in. across, in corymbs 2 in. wide; seed-vessels glabrous, with the sepals deflated.

An endemic species of the Carnic Alps and bordering mountains (Italy in Udine province, N.E. Slovenia, one station in Austrian Carinthia). It is a pleasing little shrub, one of the dwarfest of the spiraeas, and very suitable for the rock garden. In the wild it occurs only on limestone.

S. hacquetii Fenzl & K. Koch ? S. lancifolia Hoffmanns.; S. decumbens var. tomentosa Poech; S. d. subsp. tomentosa (Poech) Dostal – Of similar habit to S. decumbens, but differing in the young stems, leaves, flower-stalks and calyx being downy; in the more prominent nerves beneath the leaf; also by the sepals being more erect in fruit. Like the preceding, this too has a very limited range, but farther west, in the Alpe Venezie of Italy. Of the same garden value as S. decumbens, of which it is now usually treated as a subspecies.

These two interesting species are the only European natives that bear their flowers in corymbs on leafy shoots, all the others, except the obviously distinct S. salicifolia, having their flowers in umbel-like racemes. Also, they are mainly or wholly dioecious, as is the Himalayan S. bella.