POLLINA riON, 



447 



times like a lon^ nnrrow letter S. It is on tlie eml of this style, ari-l along 

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



Fig. 46S. 



Section of flower of cypripedium. 

 stigma ; <(, at the left stamen. Tlie 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 tiower 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 



unv/rapping the folded petals and staminodia, we shall see the anlher-bearing 



Fig. 469. 

 Epipactis \\-ith portion of perianth removed to show details. /, labellum; st . stigma: ^, 

 rostellum ; /, pollinium. 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 mo\'es to another flower the pollinia have moved 

 downward so tliat 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) attached. 



