424 



THE ORCHIDALES 



into a waxy mass, pollinium (pi. pollinia) which is attached to 

 a sticky part of the rostellum (Fig. 293, B, C}. The remarkable 

 feature about these gaudy flowers is the relation that the label- 

 lum, anther, rostellum and stigma sustain to each other. The 

 position of these organs is such that an insect visiting the flower 

 touches with some part of his body the sticky part of the rostel- 

 lum and the pollinia are thus made fast to him and carried to the 

 stigma of another flower. These devices are so elaborate in 

 many orchids that the microspores can only reach the stigma 

 through the agency of an insect. In the lower types of orchids, 

 as the moccasin flower (Fig. 292, B), a somewhat different 



FIG. 292. A simple type of the Orchidales: A, the moccasin flower, Cy- 

 pripedium /, labellum; p, the two unmodified petals; s, sepals, two being 

 united below the labellum; b, bract, partially concealing the inferior ovary. 

 B, section of the flower /, labellum; s, stigma; an, anther; st, shield-like 

 sterile stamen covering the two anthers and stigma; o, ovary; b, bract. 



arrangement is found. The bee enters the opening in the upper 

 part of the labellum and feeds upon the glands distributed along 

 the bottom. In leaving the flower he forces his way through 

 the small opening on either side of the style and so he first comes 

 into contact with the stigma and later with the anthers, which are 

 two in number and located back of the stigma. In this flower 

 the anthers are surrounded by a sticky mass and the microspores 

 are thus fastened to the insect's body to be carried to another 

 flower. In the higher types of orchids, the insect probing for the 

 nectar touches the sticky discs of the rostellum, to which the 



