Reproducing by seed and by somewhat creeping stems.
Stems prostrate to nearly erect, 10-50cm high, rooting at nodes touching the soil, square, sharply ridged on the angles, rough-hairy.
Leaves opposite (2 per node), ovate to elliptic or round, the lower ones usually broader and with longer stalks, green or with a purplish cast; margins smooth or shallowly and irregularly toothed.
Flowers in dense spikes or head-like clusters at ends of stems, usually in 3's in axils of very broad ovate or kidney-shaped bracts; calyx a 10-veined tube ending in 1 broad, scoop-shaped upper tooth and 4 thin, bristle-like lower teeth, often purplish; corolla blue-violet to purplish or rarely pinkish or whitish, 10-20mm long, of 5 united petals, irregular, tubular, 2-lipped at the end, the upper lip rounded and arched, the lower lip with 2 small side lobes and 1 larger central lobe; each flower producing 4 nutlets ("seeds"), these brownish to blackish, oval lengthwise but triangular in cross-section with 2 flat sides and the third rounded. Flowers from June to August.
Heal-all occurs both as a native plant and an introduced ornamental which has escaped from cultivation in most areas of Ontario. It is found in open woodland, meadows, pastures, waste areas, roadsides, lawns, and around buildings. Where subject to mowing or trampling such as in lawns or pastures, Heal-all will grow as a prostrate plant with stems rooting at nearly every node and producing only a few erect flowering branches; but where it grows without disturbance or in crowded situations, the stem may be erect and up to 50cm high.
It is distinguished by its square stems, leaves opposite, stalked and with smooth or irregularly toothed margins, its compact head-like inflorescence with broad ovate or kidney-shaped bracts, green or purplish calyx having the 1 upper lobe very broad, and its usually blue-violet flower with 2-lipped end.
A. Portion of a prostrate stem, rooting at the nodes and producing leafy shoots from tip as well as nodes. B. Top of flowering stem.
Heal-all flower head.
Purple flower of heal-all.
Leaf of Heal-all.
Stem of Heal-all.
Heal-all plant growing in southern Ontario in August.