SECT. II 



PHANEROGAMIA 



449 



tinguished as true, in contrast to the false dissepiments which, in 

 rare cases (e.g. Labiatae), are produced by ingrowths from the internal 

 surface of the carpels. 



The ovary is prolonged upwards as a neck-like STYLE, expanded at 

 the apex into a STIGMA, which may be of various shapes. The whole 

 organ, consisting of ovary, style, and stigma, is termed the pistil. 



A completely syncarpous gyncecium possesses but one ovary and 

 one stigma (Fig. 378, C). The cohesion of the carpels may, however, 

 be restricted to the basal portions in such a way that the ovary bears 

 as many separate styles, or a style as many stigmas, as the number of 

 carpels united in the ovary (B, D). The reverse case, in which only 

 the upper portions of the carpels cohere, and not the lower, occurs only 

 in the Apocynaceae and Asclepiadaceae. 



The style exhibits great variation in length and thickness. It is, 

 for example, long and filiform in Crocus, short and thick in Tulipa. It 



A B 



Fig. 379. — A, parietal ; B, axile ; C, free-central placentation. A and B in transverse section, 

 C in longitudinal section. (Diagrammatic.) 



is either traversed by an axial canal or filled with a loose parenchyma. 

 The stigma may be disc-shaped, ellipsoidal, capitate, bifurcate, or more 

 rarely, as in Iris, corollaceous. Its surface is generally velvet-like, 

 covered with papillae, and is moist and sticky. 



The ovules are always enclosed in the cavity of the ovary. They 

 are developed, as a rule, from the margin of the carpels, and are there- 

 fore in unilocular ovaries parietal (Fig. 379, A); in plurilocular, axile 

 or axillary (B). 



Sometimes a departure from this mode of development of the 

 ovules is exhibited, and the placentation instead of being marginal is 

 superficial ; the ovules are distributed, as in Butomus, over the whole 

 inner surface of the carpels. In other cases, again, the placentation is 

 free-central and the ovules appear to be produced from the floral axis 

 itself, as in the orders Centrospermae, so called on account of this 

 peculiarity, and in Primulinae (Fig. 379, 0). In the last case, the 

 anomalous position of the ovules is attributed to the disappearance of 

 the dissepiments, or to their coalescence and displacement. 



