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.”

Crataegus Pyracantha (Fire Thorn).—­This hardy, ornamental shrub will grow in any soil.  It should be planted early in spring on a south or south-west wall, and may be increased by seeds, by budding, or by grafting.  The profuse brilliant orange-coloured berries of the C. Lelandii (Mespilus) ensures it a place on walls and trellises.  A sunny position gives best results.  Prune in March.

Creeping Jenny.—­See “Lysimachia Nummularia.”

Crepis (Hawkweed).—­An interesting hardy annual.  It merely requires sowing in spring, and will grow in any soil.  The flowers are produced in June.  Height, 1 ft.

Cress.—­Sow at intervals of a week from March to September in the open ground, and during the winter months in frames.  A shady position is most suitable.  By these frequent sowings, and by often cutting over such as readily renew a bottom growth, a constant succession of tender shoots is obtained.

Crocus.—­Among our earliest spring flowers.  These will grow in any garden soil, but prefer rich, sandy earth.  Plant in October or November, 3 in. deep and 2 in. apart.  Take the roots up every second year, and plant the small off-sets in a nursery bed for two years, when they will be fit for the beds or borders.  Protect the bulbs from mice, as they are very partial to them, especially in winter.

Indoor Culture.—­Select strong bulbs of the seedling varieties, and plant them in succession, commencing early in autumn, in good, rich, sandy soil.  A liberal supply of water is necessary during the blooming season, but perfect drainage must be secured.  They grow well in bowls filled with wet moss or sand.  Height, 6 in. (See also “Colchicum.”)

Crotons.—­Fine-foliaged hothouse plants.  A mixture of peat and sandy loam suits their growth, and they require a good amount of light to properly colour their leaves, with a night temperature of 70 degrees.

Crowea Saligna.—­Charming greenhouse evergreen shrubs, which send forth their purple flowers in September.  They grow best in loam and peat.  Cuttings may be struck in sand under bell-glasses.  Height, 3 ft.