280 HORTICULTURIST'S RULE-BOOK. 



wedge-shape at the lower extremity, and is then inserted 



in a cleft in the end of a trunk or branch which has been 



severed. 

 Close-fertilization. The action of pollen upon the pistil of 



the same flower ; self-fertilization. 

 Coldframe. A frame covered with glass, cloth, or paper, 



without bottom heat, used for starting plants early in 



spring, for receiving plants transplanted from a hotbed 



or forcing-house, or for protecting plants during the 



winter. 

 Conservatory. A glass house for preserving or growing 



tender plants. Popularly, the term is applied to houses 



in which plants are grown for display of flowers. 

 Corm. A solid bulb-like tuber, as in the gladiolus and crocus ; 



bulbo-tuber. 

 Corolla. The inner envelope of the flower. The parts, when 



distinct, are called petals. 

 Corymb. A flower-cluster which is flat or convex on top, and 



in which the outer flower blooms first. 

 Cotyledon. A small leaf borne in the seed ; seed-leaf. In 



many plants the cotyledons rise to the surface when the 



seed germinates, and increase in size. 

 Cross. The offspring of any two flowers which have been 



cross-fertilized. 

 Cross-breed. A cross between varieties of the same species ; 



half-breed, mongrel, variety-hybrid. 

 Cross-fertilization. The action of pollen upon the pistil of 



another flower of the same species. Cross-fertilization is 



commonly used to denote the mere conveyance of pollen 



pollination but better usage confines the term to the 



action of pollen upon the pistil. 

 Cross-pollination. The conveyance of the pollen to the 



stigma of another flower. 



Crossing. The operation or practice of cross-pollination. 

 Crown-grafting. Grafting at or near the surface of the 



ground. 

 Cryptogam. One of the class of flowerless plants. These 



