Seeds. Increased by cuttings of firm shoots, taken in April, in bottom heat. =Convallaria= (Lily of the Valley). _Liliaceæ._ Increased by "crowns" or "pips" (see Fig. 17), which are the separated growing points of the roots, possessing a strong bud. These crowns can be obtained from any well established bed in the fall, but they are usually imported. =Convolvulus= (Bindweed). _Convolvulaceæ._ Seeds of the hardy annuals should be sown in spring in the open border. The hardy perennials may be increased by seeds sown in spring, by division of the roots, and by young cuttings. =Coprosma.= _Rubiaceæ._ Increased by layers and cuttings. =Coptis.= _Ranunculaceæ._ Propagated by seeds and division of the roots. =Cordia=, Varronia. _Boragineæ._ Seeds. Increased by cuttings, green or ripe, which strike root readily in sand, in heat. =Corema= (Portugal Crakeberry, Crowberry). _Empetraceæ._ Seeds. Propagated by cuttings planted during summer. =Coreopsis=, Calliopsis. _Compositæ._ The hardy annuals, which are largely grown under the name of calliopsis for summer ornamentation, by seed, which should be sown in March in a gentle heat, or outside later. The perennials are propagated also by divisions of the root in autumn or spring, or during the summer by young cuttings, which will strike freely in a cold-frame. =Coriander= (_Coriandrum sativum_). _Umbelliferæ._ Seeds sown in fall or spring. =Corn.= See Maize. =Corn Salad= (Valerianella, several species). _Valerianeæ._ Seeds sown in spring, summer or autumn. =Cornus= (Dogwood Osier). _Cornaceæ._ Increased by seed, suckers of soft wood, layers or cuttings. The herbaceous species, _C. Canadensis_ and _C. Suecica_, may be increased by division, as also by seeds. The willow-like cornuses grow from cuttings of ripe wood. Named varieties and some species are budded in many cases, especially all the weak-growing sorts. _Cornus Mas_, raised from seed, is the favorite stock. Shield-budding in late summer and veneer-grafting are most successful. (See Fig. 44.) =Coronilla.= _Leguminosæ._ By seeds sown as soon as ripe. The hardy species by division. Cuttings strike freely if placed in cold-frames or a cool house under a hand-glass in spring, and when calloused, introduced to gentle bottom heat. =Correa.= _Rutaceæ._ Seeds. May be propagated by cuttings very readily. Varieties are usually grafted on _C. alba_. =Cortusa= (Bear's-ear Sanicle). _Primulaceæ._ Increased by seed sown as soon as ripe in a cold-frame; also by carefully dividing the roots. =Coryanthes.= See Stanhopea. =Corydalis.= _Fumarieæ._ Increased by seeds, or by dividing the plants directly after flowering. The bulbous-rooted species by offsets. =Corylus= (Hazel; Cob-nut). _Cupuliferæ._