ANOMALIES IN FLOWER OE OECHID. 



373 



the column, and, in some rare cases, according to Brown, forms a sepa- 

 rate projection or filament. The upper two anthers of this inner 

 whorl are fertile in Cypripedium, and in other eases are generally 

 represented either by membranous expansions or by minute auricles 

 without spiral vessels. These auricles, however, are sometimes quite 

 absent, as in some cases of Ophrys." On this view of the homologies 

 of Orchid flowers, Darwin further remarks — " We can understand the 

 existence of the conspicuous central column, — the large size, generally 

 tripartite form, and peculiar manner of attachment of the labeUum, — 

 the origin of the clinandrium, — the relative position of the single fer- 

 tile anther in most Orchids, and of the two fertile stamens in Cypri- 

 pedium, — the position of the rosteUum, as well as of aU the other 

 organs, — and, lastly, the frequent occurrence of a bilobed stigma, and 

 the occasional occurrence of two distinct stigmas." 



Upper or posterior sepal. i 



Upper 

 petal. 



Upper 

 petal. 



LabeUum. 



Kg. 656. 



Section of the Plowbe of an Oechid {Darvdn). 



Fig. 656. The little circles show the position of the spiral vessels, which 



alternate in five -whorls, the three central groups running to the three petals are 



■connected ty a triangle. 



S S. Stigmas ; S„ stigma modified into the rostellum. 



A^. Fertile anther of the outer whorl ; Aj, Ag, anthers of the same whorl com- 

 hined with the lower petal, forming the lahellum. 



«i a^. Rudimentary anthers of the inner whorl (fertile in Cypripedium), gene- 

 rally forming the clinandrium ; a^ third anthgr of the same whorl, when 

 present, forming the front of the column. 



