H. HISPIDA (_syn Pterostyrax hispidum_).--j.a.pan, 1875. This is a shrub of perfect hardihood, free growth, and very floriferous. The flowers, which are pure white, and in long racemes, resemble much those of the Snowdrop Tree. Leaves broad and slightly dentated. It is a handsome shrub, of free growth, in light, sandy loam, and quite hardy even when fully exposed.
H. PARVIFLORA has smaller flowers than those of our commonly-cultivated plant.
H. TETRAPTERA.--Snowdrop Tree. North America, 1756. This is a very ornamental tall-growing shrub, of somewhat loose growth, and bearing flowers which resemble, both in size and appearance, those of our common Snowdrop. It is one of the most ornamental of all the small-growing American trees, and richly deserves a place in every collection, on account of the profusion with which the flowers are produced in April and May. They are snow-white, drooping, and produced in lateral fascicles of eight or ten together. It is a native of river banks in North Carolina, and is well suited for cultivation in this country.
Light, peaty soil will grow it to perfection.
HALIMODENDRON.
HALIMODENDRON ARGENTEUM (_syn Robinia Halimodendron_).--Salt tree. A native of Asiatic Russia (1779), having silvery foliage, and pink or purplish-pink flowers, axillary or fascicled. It is a neat and pretty shrub, that is rendered valuable as succeeding well in maritime districts. Quite hardy and of free growth in sandy soil.
HAMAMELIS.
HAMAMELIS j.a.pONICA.--The j.a.panese Witch Hazel. j.a.pan, 1862. This is a small species with lemon-yellow flowers. H. j.a.ponica arborea is a taller growing variety, with primrose-yellow petals, and a deep claret calyx.
The flowers are borne in cl.u.s.ters in early spring. Rarely in this country do we find this species of greater height than about 8 feet, but it is of bushy growth, though somewhat straggling in appearance. As early as the beginning of January this Witch Hazel may be found in bloom, the bare branches being studded here and there with the curious-shaped flowers, these having bright yellow, twisted petals and reddish calyces. H.j. Zuccarinianais a very desirable free-flowering variety, with pale yellow petals and a greenish-brown calyx.
H. VIRGINICA.--Virginian Witch Hazel. North America, 1736. This has smaller flowers than H.j. arborea, and they are plentifully produced in autumn or early winter. In this country it a.s.sumes the shape of an open bush of about 6 feet in height, but is usually of untidy appearance from the branches being irregularly disposed.
They all delight in cool, rather moist soil, and are of value for their early-flowering nature.
HEDYSARUM.
HEDYSARUM MULTIJUGUM.--South Mongolia. Hardly ten years have elapsed since this pretty shrub was introduced into England, so that at present it is rather rare in our gardens. It is a decided acquisition, if only for the production of flowers at a time when these are scarce. Usually the flowering time is in August, but frequently in the first weeks of October the pretty flowers are still full of beauty. It is of bushy habit, from 4 feet to 5 feet high, with oblong leaflets, in number from twenty to thirty-five, which are Pea-green above and downy on the under sides. Flowers bright red, and produced in axillary racemes. It is perfectly hardy, and grows freely in porous decomposed leaf-soil.
HELIANTHEMUM.
HELIANTHEMUM HALIMIFOLIUM.--Spain, 1656. This species is of erect habit, 3 feet or 4 feet high, and with leaves reminding one of those of the Sea Purslane. It is an evergreen, and has large bright yellow flowers, slightly spotted at the base of the petals.
H. LAEVIPES (_syn Cistus laevipes_).--South-western Europe. A dwarf shrub, with Heath-like leaves, and yellow flowers that are produced in great abundance.
H. LASIANTHUM (_syns H. formosum_ and _Cistus formosus_).--Spain and Portugal, 1780. This is a beautiful species, but not hardy unless in the South and West. It has large, bright yellow flowers, with a deep reddish-purple blotch at the base of each petal.
H. LAVENDULAEFOLIUM has lavender-like leaves, with the under surface h.o.a.ry, and yellow flowers. A native of the Mediterranean regions.
H. LIBONATES.--This species bears dark green Rosemary-like leaves, and yellow flowers that are produced very abundantly. South Europe.
H. PILOSUM.--South of France, 1831. This bears white flowers that are of good substance, and about an inch across.
H. POLIFOLIUM (_syn H. pulverulentum_).--Europe (Britain), and North Africa. This is a neat-growing shrub, of very dwarf growth, with hairy leaves and yellow flowers; and H. polifolium roseum, has pretty rosy-red flowers.
H. UMBELLATUM.--South Europe, 1731. A neat, small-growing species, with white flowers and glossy-green leaves covered with a rusty-white tomentum beneath.
H. VULGARE.--Common Rock Rose. Europe (Britain), North Africa, and West Asia. A widely distributed native plant, of dwarf growth, with linear-oblong, hairy leaves, and usually yellow flowers. H. vulgare nummularium differs in having the leaves green and sub-orbicular, with yellow flowers. H. vulgare barbaturn is of erect habit, with silky, hairy, oval leaves. H. vulgare mutabile bears pale rose flowers, marked with yellow at the base. H. vulgare grandiflorum is remarkable for the large, bright yellow flowers, and is one of the most beautiful and worthy varieties. H. vulgare ovalifolium (_syn H. serpyllifolium_) bears yellow flowers and ovate leaves, with the margins revolute. H. vulgare hyssopifolium bears reddish flowers, but the colouring varies considerably, and saffron is not uncommon.
The Rockroses are very valuable plants, in that they will succeed on poor, gravelly banks where few other plants could eke out an existence.
They cannot withstand stiff soil, nor that at all inclined to be damp, their favourite resorts being exposed, rocky ground, and dry, gravelly banks. Being readily increased from cuttings, which take root well under a hand gla.s.s or in a cool house, it is advisable, at least with the more tender forms, to have at hand a stock, so that blanks in the shrubbery may be filled up.
HIBISCUS.
HIBISCUS SYRIACUS (_syn Althaea frutex_).--Syrian Mallow. Syria, 1596.
An old occupant of our gardens, and one that cannot be too freely cultivated. When favourably situated, it often reaches 6 feet in height, with three-lobed, neatly-toothed leaves, and with large, showy blossoms that are borne towards the end of summer. The typical species has purplish flowers, with a crimson spot at the base of each petal, but others, varying in colour from snow-white to purple and blue, are common in cultivation. H. syriacus coelestis bears bright blue flowers, while H. syriacus variegatus has beautifully variegated foliage. Of the double-flowered forms, there are several beautiful and worthy plants, the following list containing some of the best varieties of this popular shrub:--
H. syriacus albo-pleno.
" amaranthus.
" amplissima.
" ardens.
" caerulea plena.
" carnea plena.
" De la Veuve.
" elegantissimum.
" fastuosa.
" Lady Stanley.
" Leopoldii.
" lilacina plena.
" paeoniaeflora.
" puniceus plenus.
" rosea plena.
" rubra plena.
" spectabilis plena.
" violacea.
HIPPOPHAE.
HIPPOPHAE RHAMNOIDES.--Sea Buckthorn, or Sallow Thorn. Though generally considered as a sea-side shrub, the Sea Buckthorn is by no means exclusively so, thriving well, and attaining to large dimensions, in many inland situations. The flowers are not at all conspicuous, but this is amply compensated for by the beautiful silvery-like leaves and wealth of fruit borne by the shrub. In not a few instances, for fully a foot in length, the branches are smothered with crowded cl.u.s.ters of bright orange berries, and which render the shrub during November and December both distinct and effective. It does best in sandy soil, and is readily increased from suckers, which are usually plentifully produced by old plants. For sea-side planting it is one of our most valuable shrubs, succeeding, as it does, well down even to high water mark, and where the foliage is lashed with the salt spray.
HOLBOELLIA.
HOLBOELLIA LATIFOLIA (_syn Stauntonia latifolia_).--Himalayas, 1840. An evergreen climbing shrub that is more often found under gla.s.s than out of doors. In the South of England, however, it is quite hardy against a sunny wall. It grows 12 feet high, with shining green leathery leaves, and fragrant purplish-green flowers. H. latifolia angustifolia has decidedly narrower leaves than the species, but is in no other way different.
HYDRANGEA.
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 j.a.ponica; 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.--j.a.pan, 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.