This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
The habitat of this plant is thickets. The habit is that of undershrubs in general, the stem being shrubby, erect, square, flattened at the margin. The leaves are large, stalkless, almost heart-shaped to egg-shaped, blunt, aromatic, glandular. The flowers are in terminal cymes, few, yellow, the petals oval, short, oblique, falling, the sepals broad, blunt, unequal, glandular, as long as the petals and stamens. The 3 styles are bent back, shorter than the capsule. The stamens are in 5 groups. The fruit is a black round berry, pulpy, blunt, imperfectly 3-celled. The plant is 1-3 ft. in height, flowering in July and August. It is a perennial undershrub.
Stinking St. John's Wort (Hypericum hircinum, L.). - This plant is established in some spots in the country in plantations, but it is not a native species. The habit is shrubby like that of the last, the stem being erect. The leaves are stalkless, lance-shaped. The flowers are yellow, with lance-shaped, acute, falling sepals. The petals are not as long as the stamens. The 3 styles are nearly erect. The plant otherwise closely resembles H. elatum (q.v.). The plant is 1-3 ft. in height, and flowers from June to August. It is a perennial shrub.
The Tall Tutsan is established in plantations, not being a native of this country, but found in Europe. The habit is that of Tutsan; it is, however, taller. The stems are 2-edged, much-branched. The leaves are heart-shaped to egg-shaped, or acute, longer. The flowers are large, yellow, on 2-winged stalks, in a few-flowered terminal cyme, the petals twice as long as the sepals, which are broad and unequal and do not fall, and nearly as large as in Tutsan. The petals are as long as the stamens, which are not as long as the nearly erect styles. The capsule is oval. The stem is 3-4 ft. in height, and flowers in June up till August or September, being a perennial shrub.
This plant is established in plantations, bushy places, hedges, and thickets. The habit is shrublike, creeping, the stem erect. The stem is nearly simple, square or flattened at the margin. It has creeping suckers, and grows and spreads freely, but rarely sets seed. The leaves are stalkless, oblong, blunt, leathery, with large scattered glands. The flowers are large, yellow, solitary (3-4 in. across). The outer sepals are rounded, half as long as the petals, which are unequal-sided, the former blunt, inversely egg-shaped. The stamens are in bundles of 5. The capsule is egg-shaped, 5-celled at the base. The plant is 6-18 in. in height, flowering from June to September. The Rose of Sharon is a perennial shrub.
Hairy St. John's Wort (Hypericum hirsutum, L.). -This plant is found in woods, copses, thickets, hedgerows. The habit is erect. The stem is rounded, downy, nearly simple, the leaves hair)' below, egg-shaped, oblong, blunt, shortly stalked, with pellucid or nearly transparent glands (none on the margin), dotted. The flowers are pale-yellow, in the axils, or terminal in forked panicles, the sepals linear-oblong, nearly acute, fringed with shortly-stalked glands. The petals are twice as long as the sepals, and lance-shaped, acute, tipped with stalked glands. The styles fall. The stamens are in bundles of three. The plant is 1-3 ft. in height. It flowers in July and August, and is a herbaceous perennial.
Mountain St. John's Wort (Hypericum mon-tanum, L.). - The habitat of this plant is thickets on calcareous soil, bushy limestone hills, copses, in gravelly and chalky soil. The habit is erect or ascending. The stems are smooth, round, rigid, slender, leafless above. The leaves are membranous, egg-shaped, oblong, blunt, stalkless, with pinholes and transparent glands, and black dots near the border, the upper heart-shaped, linear, downy below. The pale-yellow flowers are in dense terminal panicles, fragrant. The petals are without glands, twice as long as the sepals, elliptic, entire, the sepals lance-shaped, acute, with a fringe of shortly-stalked glands. The styles are half as long as the capsule, the stamens in 3 bundles. The plant is 1-3 ft. in height, and flowers from June to August. It is a herbaceous perennial.