Varieties are multiplied by suckers and by root-cuttings. The suckers spring up freely about the old plants, especially if the roots are broken by the cultivator; but they have few fibrous roots and are inferior. The best plants are obtained from root-cuttings. Roots from one-fourth to three-eighths inch in diameter are selected for this purpose. The roots are dug in the fall, cut into pieces an inch or two long, and stored until early spring. They may be buried in boxes of sand after the manner of stratified seeds, or stored in a cool cellar; callusing proceeds most rapidly in a cellar. The pieces are planted horizontally an inch or two deep, in loose, rich soil. It is best to put them in a frame and give them slight bottom heat, although they will grow if planted in the open in April or May, but the plants will make much less growth the first season. Some varieties do not strike quickly without bottom heat. When the variety is scarce, shorter and slenderer pieces of root may be used, but these demand bottom heat. The heat in the frames is usually supplied by manure, or the heat of the sun under the glass may be sufficient. In these frames the cuttings can be started in the north late in March, or some six or eight weeks before the plants can be set out-doors without protection. When the weather has become somewhat settled, the plants may be planted out, and by fall they will be two to three feet high. =Black Boy.= See Xanthorrhœa. =Bladder-nut Tree.= See Staphylea. =Bladder-pod or -seed.= See Vesicaria. =Bladder Senna.= See Colutea. =Blakea.= _Melastomaceæ._ Increased by cuttings taken from shoots that are about ripe; plant in a pot of sand, and plunge in a moist heat, under a hand-glass. =Blandfordia.= _Liliaceæ._ Propagated by seeds and offsets, or by division of the old plants, which must be done when repotting. =Blazing Star.= See Liatris. =Bleeding Heart.= See Dicentra. =Blephilia.= _Labiatæ._ Increased by division of the roots in early spring. =Bletia.= _Orchideæ._ Propagated by divisions, which should be made after the plants have finished flowering, or previous to their starting into growth. These are terrestrial, and their flat, roundish pseudo-bulbs are usually under ground. They bear division well, especially _B. hyacinthina_, which may be cut up into pieces consisting of a single pseudo-bulb. (See under Orchids.) =Blood Flower.= See Hæmanthus. =Blood-root.= See Sanguinaria and Hæmodorum. =Blueberry.= See Vaccinium. =Blue-eyed Grass.= See Sisyrinchium. =Blumenbachia.= _Loaseæ._ Propagated by seeds sown in pots in spring, and placed in a gentle heat. =Blumia.= See Saurauja. =Bobartia.= _Irideæ._ Propagated by separating the offsets during autumn. =Bocconia.= _Papaveraceæ._