Ch. VI, 10] MORPHOLOGY OF FLOWERS 



333 



they may grow together in any of the ways shown in 

 Figure 222, producing parietal, central, or free central pla- 

 centae, with one or several compartments. 



Typically each of the four whorls stands chrectly on the 

 receptacle independently of the other three ; but remarkable 

 interrelations of the whorls also 

 occur in various flowers, as repre- 

 sented diagrammatically in Fig- 

 ure 228. In ,some cases the 

 calyx and corolla together form 

 one structure, called perianth, 

 upon which stand the stamens, 

 as in the Hyacinth, while vari- 

 ous other combinations occur. 

 Formerly such cases were inter- 

 preted on the supposition that 

 the different whorls were united, 

 or adnate, to one another from 

 the receptacle upward ; but 

 here also the development of 

 the flower favors another inter- 

 pretation, viz. that the tube 

 which the parts occupy in com- 

 mon has developed in precisely 

 the same way as the tube of the 

 corolla or calyx, — not by a 

 union of originally free parts, 

 but as a new growth inter- 

 calated between the free struc- 

 tures and the receptacle. Especially striking is the con- 

 dition of inferior ovary (page 275), where sepals, petals, 

 and stamens stand upon its top (third flower, Fig. 228). 

 This arrangement was formerly interpreted on the sup- 

 position that the calj^x (and therefore also the corolla 

 and stamens) was united or adnate to the ovary all the 

 way up from the receptacle below ; but here also the 



Fig. 230. — The Daffodil, Nar- 

 cissus Pseudo-Narcissus, .showing 

 the large corona, an outgrowth 

 from the sepals and petals. (From 

 Bailey.) 



