iiyo 



A TEXTBOOK OF THEORETICAL BOTANY 



(Fig. 1 138), even the anther is involved, so that the separate identity of 

 stamen and perianth segment is completely lost. The vascular supply to 

 the stamen may remain separate even when the filament is entirely adnate 



Fig. 1138. — Visciiiu albuni. A, Flowering 

 shoot. B, Male flower showing three 

 anthers with multiple loculi. {After Le 

 Maout and Decaisne.) 



to a petal, but there is much variation in this respect and union of the 

 stamen bundle to the petal supply may take place quite low down, the 

 anther then being supplied by a branch from the combined bundles. We 



have already had occasion to refer to this 

 relationship and some of its features in the 

 present chapter (pp. 1094 and 1166). 



Union of the stamens to the gynoecium 

 is much less common, at least in hypogynous 

 flowers, though we have seen previously 

 that it may be involved in at least some 

 cases ot epigyny. In epigynous flowers, 

 however, even though there may be evi- 

 dence for the fusion of the lower parts of 

 the stamen to the wall of the ovary, the 

 upper parts, particularly the anthers, gener- 

 ally remain free. A further degree of fus- 



FiG. 1139. — Flower of Cypripedium ion, which occurs in some cases, between 

 with perianth removed to show ,1 ^, j ^i_ ^ 1 j 



the gynostemmm. A, Side ^^e anthers and the style, produces a com- 



view. B, Front view. {After pound Structure called a gynostemium. 



Van Tiei>hem.) rj^i /^ i • i • i i 



1 he Orchidaceae provide the most con- 

 spicuous example of this structure, which is general throughout the family. 

 One of the least reduced genera, Cypripedium (Fig. 1139), has two fertile 

 stamens and a prominent, petaloid staminode, or sterilized stamen, which are 



