56 PRACTICAL BOTANY. 



subject to great variations in form, but usually it is globu- 

 lar (capitate) and terminal, often linear and lateral. 



106. A COMPOUND PISTIL consists of a pair or a wliorl of 

 cai-pellary leaves united more or less into one piece, and 

 the degree of their union differs in proportion as the petals 

 coalesce more or less perfectly. While the pair of carpels 

 of Saxifrage make a compound pistil, their union proceed- 

 ing from below upvrard, and extending only to about 

 one half of their length, or less, the union of the two 

 carpels of Pink leaves only the two styles separate. In 

 some of our wild species of Hypericum, the 3-carpelled 

 ovary has also the three styles united into one, its three 

 stigmas remaining distinct ; and in the three-gelled pistil 

 of Tradescantia, even the three stigmas are consolidated 

 into one body. Neither the styles, therefore, nor the 

 stigmas always indicate the number of carpels of which 

 the pistil consists, although in most cases they do. 



As was stated above, the ventral suture, which is the 

 placenta, always faces the axis of the flower. Hence it is 

 evident, that, when a pair or a whorl of closed carjpellary 

 leaves become consolidated, the placentae will meet in the 

 centre of the compound ovary, and that the latter has 

 as many axile placentae, more or less united into one, as 

 there are pistil-leaves in its composition, and as many 

 cells. (PI. v., 7, 8 ; YI., Ic.) The partitions or dissepi- 

 vients of a compound ovary are, of course, double, one of 

 the two layers belonging to each carpel, and in ripe pods 

 they often split into two layers. None of the carpels, form- 

 ing the combination, can have a true dissepiment ; if any 

 ever occurs, it is a spurious one, an expansion of the dor- 

 sal suture, as in the 5-carpellary ovary of Flax. 



On the other hand, the carpellary leaves may remain 

 open and unite by their edges, as the petals in a gamope- 



