522 



PART III.— THE CLASSIFICATION OF PLANTS. 



suture, which rans therefore along the ventral surface. The cavity 

 thus enclosed (loculus) is not usually divided by dissepiments, but 

 it is a simple cavity, as in the Vetch ; such an ovary is said to be 

 unilocular. False or spurious dissepiments, formed by growths 

 on the inner surface, occur in some few instances, as in Astragalus. 

 When, on the other hand, several carpels cohere to form a syn- 

 carpous ovary, it is polymerous {di- tri- or tetra-merous, etc). The 

 syncarpous ovary is unilocular (Fig. 836 B) when the individual 

 carpels cohere simply by their edges without any portion of them 

 projecting inwards ; but if the margins project into the cavity so 

 as to form incomplete longitudinal dissepiments, the ovary is cham- 

 bered (Fig. 336 C), e.g. Poppy; but since the chambers are open to- 

 w^ards the centre, the ovary is still unilocular. When the margins 

 form dissepiments which meet in the middle, the ovary is multilo- 

 cular ; sometimes the margins turn outwards again towards the cir- 

 cumference. 

 In the last 

 case the in- 

 d i vi d ua 1 

 loculi are 

 c o m p letely 

 separated ; 

 but there 

 are others 

 in which 

 the margins 

 of the car- 

 pels do not extend so far towards the centre at the upper part as 

 at the lower, but the two margins of each carpel simply cohere 

 together above ; consequently the lower part of the ovary is poly- 

 merous and multilocular, while the upper part is composed of a 

 number of monomerous ovaries, e.g. Saxifraga (Fig. 335 D). In 

 all these cases the floral axis may grow up into the interior of the 

 cavity of the ovary, and when the ovary is multilocular the axis 

 may coalesce with the dissepiments. 



False dissepiments may be formed in polymerous ovaries by in- 

 growths from the internal surface of the carpels ; thus the ovary 

 of the Boraginaceae and Labiatae is originally bilocular, but each 

 loculus becomes divided into two by a false dissepiment, and when 

 the fruit is ripe the four loculi separate completely ; similarly, the 

 unilocular ovary of the Cruciferae becomes spuriously bilocular. 



Fig. 336.— Transverse section of ovaries; p placenta. A Monomerous 

 and unilocular; r dors^al suture ; b ventral suture ; p placentation mar- 

 ginal. B Polymerous and unilocular ; placentation parietal. C Poly- 

 merous and many-chambered, but unilocular ; placentation parietal. 

 D Polymerous and multilocular ; placentation axile. 



