THE ORCHID FAMILY 



161 



Fig. 148. — Pollen-masses at the 



end of a pencil: 1. immediately on 



the withdrawal of it, 2. one or two 



minutes afterwards. 



tlie lip, is divided into three narrow lobes and drawn out into a 

 long, slender spur. Close to the entrance to the spur we find 

 the stigma vjf the pistil with a sticky surface, and above it, the 

 sessile stamen which contains two pollen-masses in a pouch each; 

 these look like two small clubs, and end in a gummy disk below, 

 covered under a small, knob-like 

 projection. 



This very peculiar structure of 

 the Orchid-llower is fully under- 

 stood only when we study the 

 mode of its pollination by bees. 



The flowers are small, indeed, 

 but their white colour makes them 

 visible as they are raised by their 

 stems above their surroundings. 

 A bee seeing them alights on the 

 expanded under-lip which affords 

 a convenient landing place. It 



then stretches its proboscis into the spur in search of nectar. 

 Just at the entrance to the spur are the projections which 

 contain the sticky disks of the pollen-clubs under small lids. 

 As the insect touches these with its head, they break up, and 

 at once the sticky disks settle on the forehead of the insect. 

 On leaving the flower, the pollen-masses are drawn out of their 

 pouches, and the bee flies away with them. If this process is 

 imitated by gently inserting a pointed pencil into the spur and 

 withdrawing it, one can see that the clubs which are erect in 

 the beginning bend forwards after a minute or two (fig. 148). 

 The same happens, of course, when the pollen-clubs are on the 

 head of the bee. When it thus visits another flower, the pollen- 

 masses must touch the stigma of it, and this will detach some 

 or all of the pollen from the bee's head. The flower is thus 

 fertilized. 



4. The Fruits are capsules containing numerous powdery 

 seeds which are shaken out and dispersed by the wind when the 

 capsules split into six valves. 



11 



