This species, which occurs over a wide area of North America east of the Rocky Mountains is so closely allied to the Old World S. racemosa that some authorities do not separate them. The American shrub is distinguished by its young shoots, leaves and flower-stalks being downy, the brown pith, and the fruit-panicles not so densely packed with berries.
f. leucocarpa (Torr. & Gr.) Rehd. S. pubens var. leucocarpa Tott. & Gr. – Fruits white.
f. xanthocarpa (Cockerell) Rehd. S. racemosa f. xanthocarpa Cockerell – Fruits yellow.
S. callicarpa Greene S. racemosa var. callicarpa (Greene) Jeps.;? S. pubens var. arborescens Torr. & Gr. – This replaces S. pubens in western N. America from Alaska to California. The mature leaves tend to be less downy beneath and the fruit-panicle flatter. Uncommon in cultivation, but evidently a fine shrub in the wild, attaining a height of 20 ft in places. Yellow-fruited plants are sometimes found.