in botany, a genus of the didynamia gynoephermia class. The upper labium is vaulted, and the inferior one reflected in the edges; the intermediate labium being large, and emarginated; and the stamens are reflected towards the sides. There are 12 species, three of them natives of Britain, viz. the germanica, or base horsetail; the filiflora, or hedge nettle; and the palustris, or clown's all heal.