HOW PLANTS ARE PROPAGATED. 



189 



s of two anil Uiree ctlla. 



Fig. 189, pistil of Common St. John's-wort, plainly composed of three simple ones, 

 with their ovaries completely united, while their slender styles are separate. 



Fig. 190, same of Shrubby St. 

 John's-wort, like the last, but with 

 the three styles also grown together 

 into one, the little stigmas only sepa- 

 rate ; 'but as it gets older this style 

 generally splits down into three, and 

 when the pod is ripe it also splits 

 into three, plainly showing that this 

 compound pistil consists of three 

 united into one. On turning now 

 to Fig. 8 and Fig. 10 to 12 on the 

 same page, it will be seen that the 

 pistil in Morning-Glory and in Lily 

 comiiouiKi pi.tiiH of two anj three cBib. IS a compouud onc, madc of three 



united even to their stigmas. This is shown externally, by the stigma being some- 

 what fhree-lobed in both. And it becomes perfectly evident on cutting the ovary 

 in two, bringing to view the three cells (Fig. 12, as in Fig. 189, 190), each an- 

 swering to one simple ovary. 



216. So compound ovaries generally have as many cells as there 

 are simple pistils or pistil-leaves in their composition ; and have the 

 placentas (199) bearing the seeds all joined in the centre : that is, the 

 placentas or compound placenta in the axis. But sometimes the 

 partitions or divisions between the cells vanish, as in Pinks : then 

 the compound pistil is only one-celled. And sometimes there never 

 were any partitions ; but the pistil was formed of two, 

 three, or more open pistil-leaves grown together from 

 the first by their edges, just as petals join to make a 

 monopetalous corolla. Then the ovules or seeds, or 

 the placentas that bear them, are parietal, that is, are 

 borne on the parietes or wall of the ovary. Fig. 191 

 is the lower part of a compound ovary, with three joa- 

 n'eta/ju/aceratas or seed-bearing lines ; and Fig. 192 is 

 a diagram, to explain how such a pistil is supposed to be made of three leaves united 

 by their edges, and these edges bearing the ovules or seeds. 



One-celled compound ovary, with placental 

 parietal. 



