Studies of Selected Spermatophytes. 227 



found that- other wild bees of smaller size are on the whole 

 more efficient than the bumble-bee in pollinating the Iris. 

 Butterflies sometimes visit these flowers ; but since they sip 

 the nectar without bodily entering the flower, they perform 

 no service. Certain beetles have been found to pierce the 

 nectary from the outside so that the nectar flows out and 

 is wasted. Such insects may be looked upon as robbers. 

 Many other flowers besides the Iris suffer depredations of 

 this kind. 



Compare the flower of the Iris with that of Sisyrinchium 

 or Nemastylis, and write an account of the modifications 

 from these simpler types which the Iris has undergone, 

 specially adapting it to cross pollination by bees. The 

 account should be illustrated by simple diagrams clearly 

 showing the main facts. 



Cypripedium pubescens (or other species). 



Make drawings of the flower and dissected parts from 

 the best points of view to clear up the following points : 

 The number and form of the sepals and petals ; the form 

 of the stamens and pistil and their position relative to the 

 other parts ; where insects (small bees in particular) enter 

 the flower and where they leave it. How, on leaving the 

 flower, bees collect the sticky pollen on the upper part of 

 their bodies ; and how after this, on leaving another flower, 

 they leave this pollen on its stigmas and then gather 

 another load of pollen. 



Why do not insects leave the flower by the same open- 

 ing through which they enter it ? Find the nectar-secreting 

 hairs at the base of the large hollow petal termed the lip. 

 Would the other two petals and the sepals probably serve 

 in attracting insects ? Is the nectar protected from the 

 rain ? By what devices is the pollen protected against 



