DEVELOPMENT OF PLANTS 



383 



meaning that the pistil matures first. It must also be borne in 

 mind, although the devices for effecting a crossing are almost 

 universal among the various groups of angiosperms, that there 

 are equally elaborate provisions for the transference of the 

 microspores of perfect flowers to the stigmas of their own flower. 

 This is called autogamy and would appear to be a provision for 

 setting seed in case crossing fails. 



From the above discussion we might characterize the primitive 



\ 



FIG. 263. Development of the perianth: A, inflorescence of Quercus or 

 oak mi, inflorescence with flowers bearing only microsporophylls; mg, 

 inflorescence with flowers bearing megasporophylls. B, flower of oak, en- 

 larged, consisting of several microsporophylls and a perianth of minute scale- 

 like organs. C, flower of Erythronium or fawn lily. The perianth of six con- 

 spicuous leaf-like organs. D, flower of Melandryum or day pink ca, calyx of 

 green sepals; c, corolla of five delicate petals. 



flowers as consisting usually of a large and indefinite number of 

 sporophylls, spirally arranged upon the receptacle which is suf- 

 ficiently elongated as to permit the separate attachment of each 

 organ. Following the development of this type of flower, there 

 appeared as the next advance, minute outgrowths about the 

 sporophylls, known as the perianth. In its simplest form this 



