THE ANGIOSPERMAE 



1339 



Fig. 1248.- — Asaiiim eiiropaeum. A, Shoot with flower and two foHage leaves. B, Gynoe- 

 cium with divergent styles and terminal stigmas. C, Vertical section of flower in 

 early stage with fly about to crawl down between the stylar arms. D, Later stage 

 with anthers discharging. (Partly after Le Maoiit and Decaisne.) 



found in other members of the Aristolochiaceae. Many pitfall and trap 

 structures have been produced by various species of Aristolochia, with the 

 result that the large, tubular flowers have become greatly modified and have 

 earned the popular name of " Dutchman's Pipes ". These pollination 

 mechanisms will be discussed under the description of the Family (see 

 p. 1706). 



Under the present heading 

 can be included some of the most 

 remarkable of the mechanisms 

 in the Orchidaceae although 

 they are not strictly dipterous 

 flowers. Two well-known ex- 

 amples are those of Cypripediiini 

 and Coryanthes. 



In Cypripediiim the labellum 

 forms a large pouch with an 

 inturned edge, its proximal part 

 being rolled into a tube sur- 

 roundi'ng the reproductive 

 organs (Fig. 1249). The pos- 

 terior stamen is here a large, 



sterile staminode, shaped like a 



oKif^lrl wViilp tVip twr. lateral FiG. 1249.— Cv/)r2>e<y/»7«, cultivated hybrid, show- 



Shield, While the two lateral .ngLntal aspect of flower with large pouched 



anthers of the inner whorl are labellum. 



