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- 

 ium), which must be pulled 



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



plete flower, showing three broad se- OUt bodily. An illustration 



pals, three narrower petals (one of Q f a CO mmon method of 

 which forms the long lip and the much . 



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



which extends the concave stigmatic f ji 



surface (at the bottom of which the fr m the Common rein Or- 



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



enlarged view of pollen sacs, stigmatic 



surface, and buttons ; C, a pollinium tWO pollen maSSCS temil- 



removed; D, a button enlarged. Af- nateg j n a gticky 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 



