Division of the crowns when possible; or by seeds and suckers. The plants are oftenest imported directly from the tropics. =Zanthorhiza.= See Xanthorhiza. =Zanthoxylum= (Prickly Ash). _Rutaceæ._ Seeds, suckers, but more often by root-cuttings. =Zea.= See Maize. =Zephyranthes=, including Habranthus (Flower of the West Wind, Zephyr Flower). _Amaryllideæ._ May be multiplied by seeds; or by separating the bulbels. =Zingiber=, including Zerumbet (Ginger). _Scitamineæ._ Propagated by division. =Zinnia= (Youth-and-old-Age). _Compositæ._ Seeds, sown either in-doors or out. =Zizania= (Wild or Indian Rice). _Graminæ._ Seeds, sown along water courses or in bogs in fall or spring. =Zizyphus.= See Jujube. =Zygadenus=, including Amianthemum, Anticloa. _Liliaceæ._ Readily multiplied by seeds or by divisions. =Zygopetalum.= _Orchideæ._ Division. (See also under Orchids.) =Zygophyllum= (Bean Caper). _Zygophylleæ,._ Seeds, when they can be had; otherwise by cuttings in a frame. CHAPTER VII. POLLINATION =Pollination.=--The act of conveying the pollen from the anther to the stigma. =Close-pollination=--=Self-pollination=.--The transfer of pollen to a stigma of the same flower. =Cross-pollination.=--The conveyance of pollen to the stigma of another flower. =Crossing.=--The operation or practice of cross-pollinating. =Fertilization=--=Fecundation=--=Impregnation=.--The action of the pollen upon the ovules. =Close-fertilization=--=Self-fertilization=.--The action of pollen upon the ovules of the same flower. =Cross-fertilization.=--The action of pollen upon the ovules of another flower of the same species. =Individual-fertilization.=--Fertilization between flowers upon the same plant. =Hybridizing.=--The operation or practice of crossing between species. =Hybridism=--=Hybridity=.--The state, quality or condition of being a hybrid. =Hybridization.=--The state or condition of being hybridized, or the process or act of hybridizing. =Cross.=--An offspring of any two flowers which have been cross-fertilized. =Individual-Cross.=--An offspring of two flowers on the same plant. =Cross-breed=--=Half-breed=--=Mongrel=--=Variety-hybrid=.--A cross between varieties of the same species. =Hybrid.=--An offspring of plants of different species. =Half-hybrid.=--A product of a cross between a species and a variety of another species. =Derivative or Derivation-hybrid=--=Secondary-hybrid=.--A hybrid between hybrids, or between a hybrid and one of its parents. =Bigener=--=Bigeneric hybrid=.--A hybrid between species of different genera. =Bigeneric half-breed.=--A product of a cross between varieties of species of different genera. =Mule.=--A sterile (seedless) hybrid.