Propagated by seeds. By half-ripened cuttings of side shoots; these will root easily in spring or summer, if planted in sand and placed in bottom heat, under glass. =Cockscomb.= See Celosia. =Cocoanut= (_Cocos nucifera_). _Palmæ._ The nuts are buried in nursery rows, and the young trees are transplanted. A more common practice is to remove the buried nuts, when they begin to sprout, to the place in which the tree is to stand. A nut is then placed in a hole some two feet deep, which is gradually filled in as the plant grows. In from six to eight years the tree begins to bear. =Codiæum=, Croton. _Euphorbiaceæ._ New varieties are produced by seed. Increased by taking off the tops of any strong leading shoots, and making them into cuttings. They may be struck by placing singly in small pots and covering with bell-glasses, in strong, moist heat, where they will soon emit roots, without losing any of the leaves attached at the time they were inserted. Or they may placed in a bed of sand. =Coffea= (Coffee-tree). _Rubiaceæ._ Propagated by seeds. Also by ripe cuttings, which strike freely in sand under glass, in moist heat; and the young plants so raised produce flowers and fruit more readily than those grown from seed. =Coffee-tree=, Kentucky. See Gymnocladus. =Colchicum= (Autumn Crocus). _Liliaceæ._ Seeds, sown as soon as ripe in a protected place. Separation. =Coleus.= _Labiatæ._ Increased by seeds for new varieties. By cuttings with the greatest freedom at almost any time of the year, and, with a good moist heat, they will quickly form fine specimens. (Fig. 53.) =Colletia.= _Rhamneæ._ Increased by cuttings of half-ripened wood, six to eight inches in length, in a cool greenhouse. =Collinsonia.= _Labiatæ._ Increased readily by dividing roots in spring; also seeds. =Colocasia.= See Caladium. =Columbine.= See Aquilegia. =Colutea= (Bladder Senna). _Leguminosæ._ Propagated by seeds, or by cuttings, placed in sandy soil in the autumn. =Combretum.= _Combretaceæ._ Increased by cuttings of side shoots, taken off with a heel, planted in sand under glass, and placed in heat. =Comesperma.= _Polygaleæ._ Seeds. Propagated by young cuttings, which root freely if planted in sand under glass. =Comfrey.= See Symphytum. =Commelina.= _Commelinaceæ._ Increased by seeds. By cuttings, which will root in sand, in a gentle hot-bed. =Comocladia= (Maiden Plum). _Anacardiaceæ._ Seeds. Propagated by ripened cuttings, which will root in sand if placed under glass, in heat. =Comparettia.= _Orchideæ._ Increased by division of the plants. (See under Orchids.) =Comptonia= (Sweet Fern). _Myricaceæ._ Seeds; by dividing the clumps, and by layers, which should be put down in autumn. =Conocarpus= (Button-tree). _Combretaceæ._