304 THE FLOWER. 



Family (Ord. Cistacese), Drosera (Fig. 390), &c. Also, in an 

 ovary of two carpels, by the Caper Family (Ord. Capparidaceas), 

 the Fumitory Family (Fig. 298), the Gooseberry 

 (Ord. Grossulacea?), &c. 



553. An ovary with parietal placentae is neces- 

 sarily one-celled ; except it be divided by an anoma- 

 lous partition, such as that of Cruciferous plants, &c. 



554. A compound pistil of this kind may have the 

 sutures ovuliferous, or develope placenta?, only at 

 some particular part, as at the summit or the base 

 of the cell ; and there few or only solitary ovules 

 may be developed, as in the Thrift (Ord. Plumba- 

 ginacea?), in Composite, &c., which reduces the 



case to the greatest simplicity. The confluence of two or more 

 basilar parietal placentae will account for the free central placen- 

 tation in cases where no dissepiments are discernible at an early 

 period, as in the Primrose Family. 



555. It will be seen that parietal placenta are necessarily dou- 

 ble, like -the placenta of a simple ovary, or of each carpel of a 

 compound plurilocular ovary ; but with this difference, that in 

 these cases the two portions belong to the two margins of the same 

 carpel ; while in parietal placentae they are formed from the coales- 

 cent margins of two adjacent carpels. This will readily appear 

 on comparing the diagrams, Fig. 379, 381, with Fig. 385, 386. 



556. The number of carpels of which a compound ovary con- 

 sists is indicated by the number of true dissepiments when these 

 exist (547) ; or by the number of placenta?, when these are parie- 

 tal (552) ; or by the number of styles or stigmas, when these are 

 not wholly united into one body. Thus a simple pistil has a single 

 cell, a single placenta, and a single style. A pistil of two carpels 

 may be two-celled, with two placenta?, two styles, &c. 



557. There are, however, some exceptions which qualify these 

 statements : 1. Each placenta being a double organ (555), it oc- 

 casionally happens that the two portions are separated more or 

 less, as in Orobanchaceous plants, where a dicarpellary ovary ap- 

 pears on this account to have four parietal placentse ; either ap- 

 proximate in pairs (as in our Cancer-root, Conopholis), or equidis- 

 tant (as in Aphyllon). 2. Analogous to this is the case where 



FIG. 390. Pistil of Drosera filiformibus, with three 2-parted styles ; the ovary cut across, 

 showing three parietal placentae. 



