HYDRANGEA ARBORESCENS.—North America, 1736. This is a plant of large growth, but the flowers are greenish-white, and by no means conspicuous.
H. HORTENSIS (syn Hortensia opuloides).—China, 1790. This is an old-fashioned garden shrub that is only hardy in the south and west of these islands and in the vicinity of the sea. In some of the forms nearly all the flowers are sterile, the calyx-lobes being greatly expanded, and in others the outer flowers only are sterile. According to the nature of the soil the flowers vary much in colour, some being pure white, others pink, and others of varying shades of blue. There are some very beautiful and distinct varieties, such as H. hortensis japonica; H. hortensis Otaksa, with large panicles of sterile blue flowers; H. hortensis rosea-alba, with large rosy flowers; H. hortensis Thomas Hogg, a very free-flowering and welcome form; H. hortensis mandschurica, and H. hortensis stellata flore-pleno, with partially double flowers, are worthy of attention.
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.
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.
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.