FLOWERS. 



157 



149. The Floral Envelopes consist of two or more whorls of 

 transformed leaves; of which part is calyx, its leaves being 

 called sepals, and part corolla, its 'eaves being called petals. 



150. The sexes are also transformed leaves. (187.) 



151. The calyx is always the outermost, the corolla is al- 

 ways the innermost whorls; and if there is but one floral 

 envelope, that one is calyx. 



152. Usually the calyx is green, and the corolla coloured 

 and more highly developed; but the reverse is frequently the 

 case, as in Fuchsia, Ribes sanguineum, &e. 



153. A Flower being, then, an axis surrounded by leaves, 

 it is in reality a stunted branch ; that is, one the growth of 

 which is checked and its power of elongation destroyed. 



154. That Flowers are stunted branches is proved, firstly, 

 by all their parts, especially the most external, occasionally 

 reverting to the state of ordinary leaves ; secondly, by their 

 parts being often transformed into each other; and, thirdly, 

 by the whorls of flower-buds being dislocated and actually 

 converted into branches whenever any thing occurs to stimu- 

 late them excessively. 



155. Their most essential distinctive character consists in 

 the buds at the axilla* of their leaves being usually dormant, 

 while those in the axilla pf ordinary leaves are usually active. 



156. For this reason while Leaf-buds can be used for the 

 purpose of propagation, flower-buds cannot usually be so 

 employed. 



157. Being stunted branches, their position on the stem is 

 the same as that of developed branches 



158. And as there is in all plants a very great difference in 

 the developement of leaf-buds, some growing readily Into 

 branches, others only unfolding their leaves without elonga- 

 ting, and many remaining altogether dormant, it follows that 

 flower buds may form upon plants of whatever age and in 

 whatever state 



159. But to produce a general formation of flower-buds it is 

 necessary that there should be some general predisposing 

 constitutional cause, independent of accidental circumstances. 



160. This predisposing cause is the accumulation of sap and 

 of secreted matter. 



161. Therefore whatever tends to retard the free flow of 

 sap, and causes it to accumulate, will cause the production of 

 flower-buds or fertility. 



162. And on the other hand, whatever tends to produce 

 excessive vigour causes the dispersion of sap, or prevents its 

 elaboration and causes sterility. 



163. Transplantation with a partial destruction of roots, 

 age, or high temperature accompanied by a dry atmosphere, 

 training obliquely or in an inverted direction, a constant 

 destruction of the extremities of young growing branches, 

 will all cause an accumulation of sap, and secretions ; and 



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