Marrubium

Perennial herbs, usually tomentose or lanate. Leaves petiolate, rugose, toothed. Inflorescences of spaced verticils; verticils dense, often glomerate, many-flowered; bracts leaf-like, becoming smaller towards apex; bracteoles usually present, linear-subulate; flowers sessile. Calyx tubular, widening towards mouth, 5-10-nerved, densely hairy inside mouth; teeth 10, subequal, spine-tipped, recurved or hooked. Corolla small, white to purplish; tube included in calyx, glabrous or with a ring of hairs within; upper lip erect, almost flat or concave, almost entire to deeply 2-fid; lower lip slightly longer than upper, spreading, 3-fid, middle lobe broader and emarginate. Stamens 4, didynamous, included in corolla lobe, anterior pair the longer; anthers 2-thecous, thecae divaricate, confluent. Style 2-lobed at apex, lobes obtuse. Nutlets ovoid, smooth truncate at apex. x = 17 (7, 9) (polyploidy).