Prunella vulgaris, the common self-heal, heal-all, woundwort, heart-of-the-earth, carpenter's herb, brownwort or blue curls,[4][5][6][7] is a herbaceous plant in the mint family Lamiaceae.

Prunella vulgaris grows 5–30 cm (2.0–11.8 in) high,[8] with creeping, self-rooting, tough, square, reddish stems branching at the leaf axes.

[10] The flowers grow from a clublike, somewhat square, whirled cluster; immediately below this club is a pair of stalkless leaves standing out on either side like a collar.

[12][13] Prunella vulgaris is a perennial herb native in Europe, Asia, Africa, and North America, and is common in most temperate climates.

[21] It is also a main ingredient in several herbal teas in southern China, including commercial beverages such as Wong Lo Kat.