38 NATURE SKETCHES IN TEMPERATE AMERICA 



being as interesting in their adaptation to insect visitors as 

 are the remarkable orchids. 



A more minute examination shows that the purple flower 

 has the corolla deeply divided into five parts. Next to the 

 corolla is a crown of five spreading hoods, each bearing within 

 a slender incurved horn. The five stamens are attached to 

 the corolla; the filaments are joined into a tube enclosing the 

 pistil. The anthers are joined to the stigma and flexed inward 

 and winged, broadening below the middle', and between these 

 anther wings is a sUt — the stigmatic chamber. This fissure 

 is bridged above by the pollen-bearing organ known as the 

 corpusculum. The latter may be compared to a wish-bone in 

 shape; each flattened side is called a polEnia and forms part 

 of two neighboring anthers. The upper part is formed into 

 a wedge-shaped sUt. One of the corpuscula hes within each 

 of the five slits of the crown. Opposite the anthers there are 

 five fleshy, leaf-like organs which secrete a large quantity of 

 honey. 



Mtiller says : " When insects creep about the umbels in search 

 of honey, attracted by the sweet scent of the flowers, they slip 

 upon the smooth parts of the flower until a foot enters the 

 wide inferior part of the slit, in which it gets a firm hold. When 

 the insect tries to draw its foot out in order to proceed farther, 

 the diverging claws are caught by the opposed edges of the 

 anther wings and guided upward in the slit, so that one or 

 the other of the two claws is brought without fail into the notch 

 in the lower border of the corpusculum and there held fast. 

 If the insect now draws its foot forcibly out, it brings with it 

 the corpusculum and two pollinia attached to it by their reti- 

 nacula. The pollinia stand wide apart when they are extracted, 

 but the retinacula twist upward as they dry, bringing the 

 pollinia so close together that they may easily be introduced 

 into another slit. As the insect moves over the umbel, its 

 foot, bearing the pollinia, slips into the lower part of a slit of 

 another flower; and this time, as the leg is drawn up, the pollinia 

 are left in the stigmatic chamber opposite to the stigma, since 

 the slit is too narrow to admit of their further passage upward, 

 and the insect, freeing its foot by a violent pull, snaps the 

 retinacula and so extricates itself. The pollinia are left behind 



