GROUP IV. — PHANEROGAMIA : ANGIOSPERMj;. 



503 



due to the polycyclic development of the corolla, the additional 

 whorls being tnther new formations, or the result of the more or 

 less complete replace- 

 ment of the sporophyDs 

 by petals. 



An important case is 

 that to be found in 

 several Dicotyledonous 

 orders (Ericacea?, Rho- 

 doraceae, Pyrolacea?, 

 Crassulaceae, Fig. 318, 

 Saxifragaceae, some 

 Caryophyllace.TB, Fig. 

 317; Onagraceae, Fig. 

 323 ; Geraniacese, Ox- 

 alidaceee, Zygophyllacese, 

 Rutacese, Fig. 317 C) 

 where the flower is diplo- 

 stemonous, and the 

 androecium is apparently dicyclic : but the flower is not simply 

 diplostemonous (as in the Monocotyledons), because the whorls do 

 not alternate regularly; the stamens of the apparently outer whorl 

 are directly antipetalous, consequently the stamens of the inner 

 whorl are antisepalous, and the carpels (in encyclic flowers) are 

 antipetalous. Such flowers are said to be ohdiplostemonous (Fig. 

 317 C). 



A variation of the typical ohdiplostemonous flower is found in certain Caryo- 

 phyllaceaB {e.g. Viscaria, Fig. 317 A ; Lychnis, Cerastium, some species of 



O O 



Fig. 316.— Floral diagram of Rosaiomentosa, show- 

 ing the polycyclic androjciam and gynaeceum. (After 

 Eichler.) 



A B C 



Via. 317.— Floral dia^rrams of two Caryophyllaceous flowers illustrating two forms of 



obdiplostemony : A {Viscaria vulgaris) with antisepalous carpels: B (Spergula arvensi$) 



with antipetalous carpels (after Eichler : C diagram of ohdiplostemonous flower of 



Dictamnus. 



