H. PANICULATA.—Japan, 1874. This is one of the most distinct species, in which the flower-heads are elongated, not flat, as in most other species, and from which the finest form in cultivation has been obtained. This is H. paniculata grandiflora, in which the flowers are sterile and pure white, forming large panicles often a foot in length. It is a magnificent variety, and, being perfectly hardy, should be extensively planted for ornament. The flowers are produced in late summer, but remain in good form for fully two months, dying off a rich reddish hue.
H. QUERCIFOLIA.—Oak-leaved Hydrangea. Florida, 1803. This species has neatly lobed leaves, and terminal panicles of pinky-white, but partially barren, flowers.
H. SCANDENS.—Climbing Hydrangea. Japan, 1879. This is not very hardy, but with the protection of a sunny wall it grows freely.
The Hydrangeas require a rich, loamy soil, and, unless in maritime districts, a warm and sheltered situation. They are readily propagated by means of cuttings.
HYMENANTHERA CRASSIFOLIA.—A curious New Zealand shrub with rigid ashy-coloured branches, and small leathery leaves. The flowers are violet-like in colour, but by no means conspicuous. The small white berries which succeed the flowers are, in autumn, particularly attractive, and very ornamental. It is perfectly hardy and of free growth in light peaty earth.
HYPERICUM ANDROSAEMUM.—Tutsan, or Sweet Amber. Europe (Britain). A pretty native species, growing about 2 feet high, with ovate leaves having glandular dots and terminal clustered cymes of yellow flowers.
H. AUREUM.—South Carolina and Georgia, 1882. This soon forms a neat and handsome plant. The flowers are unusually large, and remarkable for the tufts of golden-yellow stamens with which they are furnished.
H. CALYCINUM.—Aaron’s Beard, or Rose of Sharon. South-east Europe. This is a well-known native species of shrubby growth, bearing large yellow flowers from 3 inches to 4 inches in diameter. It is a prostrate plant, with coriaceous glossy leaves with small pellucid dots, and of great value for planting in the shade.
H. ELATUM is a spreading species from North America (1762), growing to fully 4 feet in height, and bearing terminal corymbs of large, bright yellow flowers in July and August. Leaves rather large, oblong-ovate, and revolute. On account of its spreading rapidly from the root, this species requires to be planted where it will have plenty of room.
H. HIRCINUM.—Goat-scented St. John’s Wort. Mediterranean region, 1640. A small-growing and slender species, with oblong-lanceolate leaves 2 inches long, and producing small yellow flowers in terminal heads. There is a smaller growing form known as H. hircinum minus. The plant emits a peculiar goat-like odour.