POLLINA TION. 



447 



times like a long narrow letter S. It is on the end of this style, and along 

 the crest of this curve, that the stigmatic surface lies, so that the pollen 



Fig. 468. 



Section of flower of cypripedium. st, 

 stigma ; a, at the left stamen. The insect 

 enters the labellum at the center, passes 

 under and against the stigma, and out 

 through the opening b, where it rubs 

 against the pollen. In passing through 

 another flower this pollen is rubbed off 

 on the stigma. 



must be deposited on the stigmatic end or margin 

 in order that fertilization may take place. 

 Fig. 467. 862. If we open carefully canna-flower buds 



Cypripedium. which are nearly ready to open naturally, by 



unwrapping the folded petals and staminodia, we shall see the anther-bearing 



Fig. 469. 



Epipactis with portion of perianth removed to show details. /, labellum ; st, stigma ; r, 

 rostellum ; /, polfinium. When the insect approaches the flower its head strikes the disk 

 of the pollinium and pulls the pollinium out. At this time the pollinium stands up out of the 

 way of the stigma. By the time the insect moves to another flower the pollinia have moved 

 downward so that they are in position to strike the stigma and leave the pollen. At the 

 right is the head of a bee, with two pollinia (a. i attached. 



