A modern reference to temperate woody plants, including updated content from this site and much new material, can be found at Trees and Shrubs Online.




A genus of about 100 species of herbs, subshrubs, and shrubs, ranging from the Mediterranean region to China; one species (P. tuberosa, a herb) extending into Central Europe. Flowers yellow, purple, pink, or white, arranged in whorls. Calyx equally five-toothed. Corolla with a hooded upper lip, the lower lip spreading, three-lobed. Stamens four. Style-branches unequal. Nutlets three-angled.

Species articles