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 glass 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.