A herbaceous perennial growing freely wild to a height of 1 to 3 feet in uncultivated ground, woods, hedges, roadsides, and meadows; short, decumbent, barren shoots and erect stems branching in upper part, glabrous; leaves pale green, sessile, oblong, with pellucid dots or oil glands which may be seen on holding leaf to light. Flowers bright cheery yellow in terminal corymb. Calyx and corolla marked with black dots and lines; sepals and petals five in number; ovary pear-shaped with three long styles. Stamens in three bundles joined by their bases only. Blooms June to August, followed by numerous small round blackish seeds which have a resinous smell and are contained in a three-celled capsule; odour peculiar, terebenthic; taste bitter, astringent and balsamic.