84 PART I. — ORGANOGRAPHY. 



has become double the number of carpels. Similarly, though the 

 number of lobes of the stigma usually indicate the number of 

 carpels, this is not always the case. 



Placentation. According to the character of the placenta- 

 tion, syncarpous pistils may be divided into four kinds : 



i. Those with marginal placentce. In this case the ovary 

 has but one cell or loculus, and the ovules are borne on the in- 

 folded edges of the component carpels, as shown in Fig. 264. 

 Here, the number of double rows of ovules corresponds with the 

 number of carpels which compose the pistil. Many simple 

 pistils, as those of the Pea and Caltha, also have this kind of 

 placentation. 



Fig. 264. Fig. 265. Fig. 266. 



Fig. 264. — Diagram of ovary, with marg.nal placenta;. 



Fig. 265. — Diagram of ovary, with axile placentae. 



Fig. 266. — Diagram of ovary, with marginal placentae, but with the latter extended 

 toward the centre of the ovary, constituting a form intermediate between those represented 

 in Figs. 264 and 265. 



2. Those with axile placentce. In th ; s case, the ovule bear- 

 ing margins of the carpel grow inward until they meet in the 

 centre, forming an ovary which usually has as many loculi as 

 there are carpels composing it, as in Fig. 265. Thus the ovary 

 with axile placentae is a modification of one with marginal pla- 

 centas, and, as might be expected, we find every gradation be- 

 tween the two. Fig. 266 represents an intermediate form, in 

 which the marginal placentae are prolonged inward, but do not 

 meet. 



3. Those with superficial placenta. In this case, the ovules 

 are not borne on the edges or infolded margins of the carpels, 

 or at any rate, not upon these alone, but are distributed over 

 their inner surface. This form of placentation is comparatively 

 rare. It is illustrated in the compound multi-locular pistil of 

 the Water-lily, and in the simple, or slightly united, pistils of the 

 Flowering-rush (Butomus). 



