Range: Nearly all parts of the world. Native to Europe and Asia. Habitat: Fields, lawns and yards, open woods, and waste places.
A frequent pest in lawns, stooling out when beheaded by the lawn-mower and sometimes taking complete possession of the sward. It adapts itself to circumstances, fruiting when not more than two inches high or sometimes attaining to more than a foot, the square, grooved stem sometimes erect or ascending, or often prostrate. Leaves long ovate, approaching to lance-shaped, obtuse, entire or with shallow scalloped edges, usually smooth or sometimes sparsely hairy, narrowing to short petioles. Flowers in densely packed terminal and axillary spikes, clustered in threes in the axils of membranaceous, veined, and hairy bracts; the blossoms are in various shades of purple, some very deep in color, others so pale as to be nearly white; corolla tubular, with a lengthened upper lip which is arched into a hood, into which the longer of the two pairs of stamens ascend; the lower lip three-lobed and spreading; calyx also two-lipped, closed in fruit, the upper lip truncate or with three short teeth, the lower one two-cleft and pointed. Seeds four small, ovoid nutlets, which are ripening and dropping all summer. (Fig. 244.)
In fields the weed may be killed by frequent hoe-cutting. While treating a border with Iron sulfate in order to kill Chickweed, the writer discovered that the Heal-all succumbed quite as readily to its blight, the leaves blackening and falling off, while the buds ceased to grow and in a few days rotted; without leaf-growth the roots cannot survive, and therefore Prunella can be driven from the lawns by repeated sprayings without injury to the grass. The solution used was somewhat strong - about eight per cent - but grasses readily recover from much stronger "doses" of this chemical; and the beauty of the sward can afford to endure temporary injury for the sake of relief from such company.
Fig. 244. - Heal-all (Prunella vulgaris). X 1/4