CUAK. II. 



GYMNADENIA CONOPSEA. 



65 



rapidly set hard. Their nectaries are stored with free 

 nectar. With respect to the uncovered condition of 

 the discs, the last species, or Peristijlus viridis, is in 

 an almost intermediate condition. The four following 

 species compose a much broken series. In Gymna- 

 denia conopsea the vicid discs are narrow and much 

 elongated, and lie close together ; in G. albida they 

 are less elongated, but still approximate ; in Hdbenaria 

 hifolia they are oval and far apart ; and, lastly, in II. 

 ehlorantha they are circular and much farther apart. 



Gymnadenia conopsea. — In general appearance this 

 plant resembles pretty closely a true Orchis. The 

 poUinia differ in having naked, narrow, strap-shaped 



Fig. 10. 



GymXADENIA CONOPSEA. 



A. Pollinium, before the act of 

 depression. 



B. Pollinium, after the act of de- 

 pression, but before it has 

 closely clasped the disc. 



discs, which are as long as the caudicles (fig. 10). 

 When the pollinia are exposed to the air the caudicle 

 is depressed in from thirty to sixty seconds ; and as 

 the posterior surface of the caudicle is slightly hol- 

 lowed out, it closely clasps the upper membranous 

 surface of the disc. The mechanism of this movement 

 will be described in the last chapter. The elastic 

 threads by which the packets of pollen are bound to- 

 gether are unusually weak, as is likewise the case with 



