This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Perennial branching mostly woolly herbs, with petioled dentate rugose leaves, and small white or purplish flowers in dense axillary clusters, the juice bitter. Calyx tubular, 5-10-nerved, regularly 5-10-toothed, the teeth nearly equal, or the alternate ones shorter, acute or aristate, spreading or recurved in fruit. Corolla-limb 2- lipped, the upper lip erect, entire or emarginate, the lower spreading, 3-cleft, its broader middle lobe commonly emarginate. Stamens 4, didynamous, included , the posterior pair the shorter; anthers 2-celled. Style 2-cleft at the summit, the lobes short. Ovary deeply 4-lobed. Nutlets ovoid, smooth. [Name Middle Latin, perhaps from the Hebrew, referring to its bitter qualities.]
About 40 species, natives of the Old World, the following typical.
Marrubium vulgare L. Sp. Pl. 583. 1753.
Stem erect, stout, woolly, especially below, 1°-3° high, the branches ascending. Leaves oval, broadly ovate or nearly orbicular, rugose-veined, obtuse at the apex, crenate-dentate, rounded, narrowed or subcordate at the base, 1-2' long, rough, whitish above, woolly beneath; petioles 1/2' -1' long, usually exceeding the flowers; clusters all axillary, densely many-flowered; flowers whitish; calyx-teeth usually 10, subulate, more or less recurved, glabrous above, woolly below.
In waste places, Maine and Ontario to Minnesota and British Columbia, North Carolina, Alabama, Texas, Mexico and California. Also in South America. Naturalized from Europe. Native also of Asia. Old names, houndbene, marrube, marvel.