This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Characters as above. About 160 species, found in all temperate regions, and at great elevations within the tropics. The name is of Greek origin, supposed to have been applied to a species of this genus. Popularly known as St. John's Wort. There are 9 or 10 British species.
1. H. calyclnum. Rose of Sharon, Aaron's Beard. - This species has larger flowers than any other, and is the one most commonly seen in gardens. It is a prostrate creeping shrubby plant with oblong obtuse coriaceous glossy leaves with very small pellucid dots, and large terminal bright yellow flowers 3 to 4 inches in diameter. July to September. A native of South-eastern Europe, occasionally met with in this country as a waif or outcast from gardens.
2. H. hircinum. - A much-branched shrub 3 to 4 feet high. Leaves oblong-lanceolate, obtuse, quite entire, about 2 inches long; glands scattered, linear. Flowers yellow, l 1/2 inch in diameter, borne in small terminal cymes. A pretty shrub, often remaining in bloom till the end of October. Native of the South of Europe. This species emits a peculiar goat-like odour when rubbed.
3. H. Androsaemum. Tutsan, Sweet Amber. - A native erect shrubby species about 2 feet high, with ovate subcordate leaves having numerous very minute glandular dots. Flowers yellow, 6 to 8 lines in diameter, in terminal clustered cymes.
4. H. elatum. - Very near the last, but in this the flowers are rather larger, and the styles longer than the stamens. An introduced species, occasionally found in a semi-wild state.
5. H. elodes. - A very distinct native species, found in wet boggy places. It is a creeping herbaceous plant with orbicular or oblong amplexicaul villous leaves about 6 lines long, and small pale yellow flowers whose sepals are margined with reddish glands.
H. prolificum and II. Kalmianum are North American shrubby species, remarkable in having very numerous stamens only slightly united at the base into five bundles. These two species are very near in character, the leaves of the former being larger, and the flowers smaller, with more than three carpels.