This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
This pretty Arctic species has been preserved in the early deposits, in Neolithic beds at Edinburgh, and Roman deposits at Silchester. It is found at present in the Arctic and Temperate Zones in Arctic Europe, N. Africa, Temperate Asia, America, and Australia, being thus widespread. It is very common in every part of Great Britain, and in Yorkshire is found up to an altitude of 2400 ft.
It is common in damp woods also; but it is also frequent on lawns and turfy ground, where it covers wide areas, often to the exclusion of the grass itself.
The habit of Self-heal is either erect or prostrate. The whole plant is more or less hairy. The rootstock is creeping. The stems are erect or ascending, the branches often short. The leaves are egg-shaped to oblong, blunt, stalked, nearly entire or with a few teeth or divided. The upper leaves are stalkless.
The flowers are violet, purple, rarely white, in cylindrical whorls forming a dense spike, with two leaves at the base. The calyx is reddish-purple, with the very small teeth fringed with a few hairs. There are two kidney-shaped, or egg-shaped to heart-shaped, broad, long pointed bracts below each whorl which are fringed with hairs and green with purple edges.
The upper lip of the calyx has short, blunt teeth, the lower lip egg-shaped to lance-shaped, with blunt, pointed, teeth. The corolla is less than twice as long as the calyx. The nutlets are smooth and oblong.
Self-heal is about 1 ft. high. Flowers may be found between July and September. The plant is perennial, and propagated by division.
The flowers of Prunella are dimorphic. There are large, complete flowers, and others smaller and rare, which are female. In the latter only functionless stamens occur. The tube is 4-5 mm. long, and the style projects above and beyond the upper lip, the two stigmas being wide-spreading.
In the complete flowers the tube is longer, 7-8 mm. The longer stamens divide into two spreading branches at the tip, the branches being unequal, and the shorter one with the anther lobes faces the centre, the other longer one outwards, its pointed ends resting on the concave surface of the upper lip, and this causes them to lie in such a position that the insect touches them on either side of the head. They open downwards and lie on each side of the stigma. The shorter stamens are similar in structure. The bee touches the lower stigma first with its back, and afterward is covered with fresh pollen. So that when insects visit the flower it is cross-pollinated, whilst in their absence self-pollination occurs and seed is set.
Photo. Flatters & Garnett - Self-heal (Prunella vulgaris, L.)
Self-heal is visited by the Honey Bee, Bombus, Megachile, Antho-pkora, Cilissa, Lycaena, Hesperia, Melitaea.
The smooth elongated nutlets when ripe drop out around the plant, assisted by the wind.
Growing on clay soil in a variety of situations it is a clay plant.
The fungus Aeicidium prunellae attacks the leaves.
Prunella or Brunella, Brunfels, is from the German Braune, a kind of quinsy which the plant was supposed to cure, and the second Latin name refers to its widespread occurrence.
Self-heal is also called All-heal, Brown-wort, Brunei, Bumble-bees, Herb Carpenter, Proud Carpenter, Carpenter-grass, Carpenter's herb, Fly Flowers, Heart of the Earth, Hook-heal, London Bottles, Pick Pocket, Pimpernel, Prince's Feather.
Brunei is a modification of Brunella, from the German die Braune, which Gerarde describes as "an infirmitie among soldiers that lie in campe".
Self-heal is called "Heart of the Earth" because it chiefly grows on thin, poor soils, where the farmers give it the credit of eating away all the substance of the soil. Because the corolla is shaped something like a billhook it was supposed to be (by Doctrine of Signatures) a vulnerary.
It was formerly applied in cases of quinsy. Formerly it was used in gargles, being aromatic and astringent.
Essential Specific Characters: 255. Prunella vulgaris, L. - Stem erect, leaves ovate, entire, stalked, with 2 acute bracts at the base of the flowers, flowers purple, in whorls of 6, in a terminal spike, calyx flattened, dentate.