_Calochortus._--Beautiful bulbous plants, called mariposa lilies, requiring warm sheltered spots in rich gritty and well-drained soil. There are several species known, the best being _albus_, _elegans_, _luteus_, _Plummerae_, _splendens_, _Purdyi_, _venustus_ and _Weedi_.
_Caltha._--Showy marsh plants, adapted for the margins of lakes, streamlets or artificial bogs. _C. palustris flore-pleno_, 1 ft., has double brilliant yellow flowers in May.
_Calystegia._--Twining plants with running perennial roots. _C. pubescens flore-pleno_, 8 to 10 ft., has showy double-pink convolvuloid flowers in July; _C. dahurica_ is a handsome single-flowered summer-blooming kind, with rosy-coloured flowers.
_Camassia esculenta._--A beautiful bulbous plant 2 to 3 ft. high with large pale blue flowers. Also a white variety.
_Campanula._--Beautiful, as well as varied in habit and character. They are called bell-flowers. _C. pulla_, 6 in., purplish, nodding, on slender erect stalks; _C. turbinata_, 9 in., purple, broad-belled; _C. carpatica_, 1 ft., blue, broad-belled; _C. nobilis_, 1½ ft., long-belled, whitish or tinted with chocolate; _C. persicifolia_, 2 ft., a fine border plant, single or double, white or purple, blooming in July; and _C. pyramidalis_, 6 ft., blue or white, in tall branching spikes, are good and diverse. There are many other fine sorts.
_Centaurea._--Bold-habited composites of showy character; common soil. _C. babylonica_, 5 to 7 ft., has winged stems, silvery leaves, and yellow flower-heads from June to September; _C. montana_, 3 ft., deep bright blue or white.
_Centranthus._--Showy free-flowering plants, for rockwork, banks, or stony soil. _C. ruber_, 2 ft., branches and blooms freely all summer, and varies with rosy, or crimson, or white flowers. It clothes the chalk cuttings on some English railways with a sheet of colour in the blooming season.
_Cheiranthus._--Pretty rock plants, for light stony soils. _C. alpinus_, 6 in., grows in dense tufts, and bears sulphur-yellow flowers in May. _C. ochroleucus_ is similar in character.
_Chionodoxa._--Charming dwarf hardy bulbous plants of the liliaceous order, blooming in the early spring in company with _Scilla sibirica_, and of equally easy cultivation. _C. Luciliae_, 6 in., has star-shaped flowers of a brilliant blue with a white centre. _C. gigantea_ is the finest of the few known species. It blooms from February to April.