Minnesota Plant Life. 



229 



but a single functional stamen out of the group, the others be- 

 ing reduced to mere vestiges. In the lady's slipper, however, 

 two stamens of the group remain functional. The curious 

 shapes of orchid flowers are connected with insect pollination 

 and the orchid flower may be regarded as a machine, or tread- 

 mill, in which some definite species of insect, different for the 

 different species of orchids, is temporarily captured and forced 

 to work for the 

 purposes of the 

 flower. 



In the com- 

 mon r o u n d - 

 leaved orchid 

 of Minnesota, 

 which has but a 

 single stamen, 

 if a pin be in- 

 serted into the 

 spur of the 

 flower, passing 

 along a groove 

 between the 

 two pollen- 

 pouches of the 

 stamen, a 

 couple of cir- 

 cular adhesive 

 discs spring out 



and attach themselves to each side of the pin. On each of 

 these discs is a stalk at the end of which a mass of pollen- 

 spores is collected. The two little masses stand up like dimin- 

 utive Indian clubs for an instant and then droop forward. 

 Here one sees the mechanism designed for the moth that 

 pollinates the flower. When the insect comes to the plant it 

 finds attractive perhaps only one flower of the two or three 

 which are finally produced. It stands in a definite posi- 

 tion, generally upon the portion of the flower turned toward 

 the ground, and introduces its bill into the spur where a little 



FIG. 103. Yellow lady-slipper. After photograph by Mr. R. S. 

 Macintosh. 



