Cortusa Matthioli.—This ornamental hardy herbaceous plant thrives best in a mixture of peat and loam. It is advisable to give protection to the roots in winter. It may be increased by seeds or by division of the roots. It makes a good pot-plant, and produces flowers in May and June. Height, 1 ft.
Corydalis (Fumitory).—These low-growing perennials are suitable for dry positions on rock-work. They are not particular as to soil, and may be increased by division of roots, while some scatter seed in abundance. Their flowering period extends over many months. Height, 6 in. to 1 ft.
Cosmea Bipinnata.—A very pretty half-hardy annual which flowers in July. Sow the seed early in spring on a slight hotbed covered with glass, and transplant to the flower border at the end of May. Height, 2 ft.
Cosmos.—Pretty plants, the flowers resembling a single Dahlia. They are mostly hardy, but some need protection. The annuals should be raised on a hotbed in February and be planted out in May. The perennials, too, are brought forward in heat. Some flower in June, others in September. Height, 1 ft. to 3 ft.
Cotoneaster.—Evergreen shrubs which will grow in any soil and are easily increased by layers. C. Hookeriana attains the dimensions of small trees, and produces a profusion of white flowers and bright crimson berries. C. Simonsii is largely used as a hedge. Height, 6 ft. to 8 ft. C. Rupestris is a small-leaved, prostrate perennial species, bearing white flowers from May to August, followed by red berries. Height, 3 in.
Cotyledon Chrysantha (Umbilicus).—A choice Alpine succulent which thrives in a sandy loam, or in well-drained pots of the same soil. It flowers from May to August, and is multiplied by cuttings, which must be left to dry for a few days in a sunny place. Flowers are produced from May to August. Height, 3 in.
Cowslips.—Well-known hardy perennials. These require the same treatment as Primulas. Plant in a mixture of loam and peat, and divide as soon as the bloom has died off. Height, 6 in.
Cowslips, Cape.—See "Lachenalia."
Crambe Cordifolia (Tournefort, or Sea Cabbage).—This hardy herbaceous plant is suitable for a wild garden. It likes a good, rich soil, and is easily increased by seed or division. August is its flowering period. Height, 3 ft.
Crane's Bill.—See "Geranium Argentium."