248 



A TEXT-BOOK OF BOTANY 



the style sends out as a roof to the pocket (Fig. 242). 

 With such an arrangement it would seem impossible for the 

 pollen to reach the stigma unaided. The nectar is in a 



little pit at the bottom of 

 the pocket. As the insect 

 crowds its way into the nar- 

 rowing pocket, its body is 

 dusted by the pollen; and 

 when it visits the next 

 flower, and pushes aside the 

 stigmatic shelf, it is likely 

 to deposit upon it some of 

 the pollen previously re- 

 ceived. 



In the orchids, remark- 

 able for their strange and 

 beautiful flowers, the story 

 of pollination is still more 

 complicated. There are 

 usually two pollen sacs, and 

 the pollen grains are not 

 dry and powdery, but cling 

 together in a mass (pollin- 

 iwri), which must be pulled 

 out bodily. An illustration 

 of a common method of 



PIG. 243. Flower of rein orchis: A, com- 

 plete flower, showing three broad se- 

 pals, three narrower petals (one of 

 which forms the long lip and the much 



longer spur), two pollen sacs, between pollination may be obtained 



which extends the concave stigmatic 



surface (at the bottom of which the 



opening to the tube is seen); B, more chis (Fig. 243). 



enlarged view of pollen sacs, stigmatic 



surface, and buttons ; C, a pollinium 



11 

 tWO pollen 



rpn nr- 

 Each of the 

 maSSCS termi- 



removed; D, a button enlarged. Af- na tes in a Sticky disk Or 

 ter GRAY. 



button; and between them 



extends the concave stigmatic surface, at the bottom of 

 which is the opening into the long tube-like spur in the 

 bottom of which the nectar is found. Such a flower is 



