A shrub 6 to 12 in. high of rounded bushy habit; young shoots very slender, downy, armed at each joint with a pair of slender, pale, mostly twin spines 1⁄4 to 1⁄2 in. long. Leaves opposite, ovate, three- to nine-lobed or sometimes merely toothed, rounded or tapered at the base, pointed to rounded at the apex; 1⁄2 to 1 in. long, scarcely as wide; dull green, downy on both surfaces; stalk slender, 1⁄8 to 1⁄2 in. long. Flowers very shortly stalked, produced singly, in pairs, or in threes in the leaf-axils. Calyx narrowly funnel-shaped, 1⁄3 in. long, ten-ribbed, downy, spreading at the mouth into five ovate slender-pointed lobes. Corolla white, two-lipped, the lower lip three-lobed, the upper lip densely covered with long white hairs. The whole flower is about 5⁄8 in. long and about 1⁄2 in. across the calyx-lobes, which stand out beyond the corolla. It blossoms in July and August.
Native of France in the Basses Alpes and Alpes Maritimes, also of Italy; related to our native ‘black horehound’ (B. nigra). It is a long time since it was first cultivated in this country and Gerard seems to have grown it in his physic garden at Holborn in 1596. Its tenure, however, has always been uncertain and intermittent owing to its tenderness and lack of notable beauty. Its flowers, with the brush-like tuft of hairs on the corolla, are curious and interesting. It can only be grown in the warmer parts of the country and in the sunniest, sheltered spots.