EEPEODUCTIVE ORGANS OF PLANTS. 315 



etc., reproduce themselves in part by spores, each of 

 which is a single minute cell that is capable of develop- 

 ing into a plant like that from which it was thrown off. 



In very many cases a portion or "cutting" of root, 

 stem or leaf, from herb or tree, placed in moist, warm 

 earth, will grow and develop into a new plant in all 

 respects similar to the original The potato, grape, 

 banana, and sugar-cane plants are almost exclusively 

 propagated in this manner. In budding and grafting a 

 portion of stem, carrying a single bud or a number of 

 buds {scion), is planted, not in the soil, but in the cam- 

 bial layer of a living root or stem with which it unites 

 and thenQeforward grows. 



The higher orders of plants (Phanerogams) have spe- 

 cial reproductive organs, constituting or contained in 

 their flowers, whose office it is to produce seed, the essen- 

 tial part of which is the embryo, a ready-formed minia- 

 ture plant which may grow into the full likeness of its 

 parent. 



§3- 



THE FLOWEK.. 



In the higher plants the onward growth of the stem or 

 of its branches is not necessarily limited, until from the 

 terminal buds, instead of leaves, only flowers unfold. 

 When this happens, as is the case with most annual and 

 biennial plants, raised on the farm or in the garden, the 

 vegetative energy has usually attained its fullest develop- 

 ment, and the reproductive function begins to prepare 

 for the death of the individual by providijig seeds which 

 shall perpetuate the species. 



There is often at first no apparent difference between 

 the leaf-buds and flower-buds, but commonly, in the later 

 stages of their growth^ the latter are to be readily dis- 

 tinguished from the former by their greater size, and by 

 peculiar shape or color. 



