Helianthus.—The Sunflower genus, of which there are several ornamental kinds. H. multiflorus, 4 ft., and its double-flowered varieties, bear showy golden yellow flower-heads in profusion, and are well adapted for shrubbery borders; H. orgyalis, 8 ft., has drooping willow-like leaves. Many other showy species.
Helichrysum.—Composite plants, with the flower-heads of the scarious character known as Everlastings. H. arenarium, 6 to 8 in., is a pretty species, of dwarf spreading habit, with woolly leaves and corymbs of golden yellow flowers, about July.
Helleborus.—Charming very early blooming dwarf ranunculaceous herbs. H. niger or Christmas Rose, the finest variety of which is called maximus, has white showy saucer-shaped flowers; H. orientalis, 1 ft., rose-coloured; H. atrorubens, 1 ft., purplish-red; and H. colchicus, 1 ft., deep purple. Deep rich loam.
Hemerocallis.—The name of the day lilies of which H. fulva, H. disticha, H. flava, H. Dumortieri and H. aurantiaca major are the most showy, all with yellow or orange flowers. They flourish in any garden soil.
Hepatica.—Charming little tufted plants requiring good loamy soil, and sometimes included with Anemone. H. triloba, 4 in., has three-lobed leaves, and a profusion of small white, blue, or pink single or double flowers, from February onwards; H. angulosa, from Transylvania, 6 to 8 in., is a larger plant, with sky-blue flowers.
Hesperis.—H. matronalis, 1 to 2 ft., is the old garden Rocket, of which some double forms with white and purplish blossoms are amongst the choicest of border flowers. They require a rich loamy soil, not too dry, and should be divided and transplanted into fresh soil annually or every second year, in the early autumn season.
Heuchera.—H. sanguinea and its varieties are charming and brilliant border plants with scarlet flowers in long racemes. Rich and well-drained soil.
Hibiscus.—Showy malvaceous plants. H. Moscheutos, rose-coloured, and H. palustris, purple, both North American herbs, 3 to 5 ft. high, are suitable for moist borders or for boggy places near the margin of lakes.
Iberis.—The Candytuft, of which several dwarf spreading subshrubby species are amongst the best of rock plants, clothing the surface with tufts of green shoots, and flowering in masses during May and June. The best are I. saxatilis, 6 to 10 in.; I. sempervirens, 12 to 15 in.; and I. Pruitii (variously called coriacea, carnosa, correaefolia), 12 in.
Incarvillea.—I. Delavayi is the best species for the open air. It grows 2 ft. high and has large tubular rosy carmine blossoms. It likes rich sandy loam and sunny spots.