POLLINATION AND FERTILISATION 



twisted stalk to all appearance connects it to the peduncle. Cut across 

 this supposed stalk it is full of ovules in fact, it is the ovary. 



Now examine the flower, it is zygomorphic (p. 179). Note 



(iv) The perianth is gamophyllous (p. 188), six-lobed, and superior 

 (p. 183). The largest leaf of the perianth is called the labellum, and is 

 roughly divided into three lobes ; it forms a spur below, which contains 

 a nectar}'. 



(v) The single stamen, the anther of which is united with the pistil, 

 and is consequently said to be gynandrous. The stamen terminates 

 below in a little knob called the rostellum or little beak, and this stands 

 over the opening into the spur, so that an insect must push it on one side 

 to obtain honey. The anther contains two pollen-masses. 



(vi) The ovary, at the top of which the shiny, sticky stigma is seen. 

 This is protected by the rostellum, which stands in front of it. 



(vii) The pollen-masses can be extracted in the following way : With 

 a fine pointed pencil press the rostellum, and keep it pressed for 

 about twenty seconds. Now draw the pencil away slowly. On the 

 tip of the pencil the pollen-masses which have been extracted from the 

 anther lobes will be seen. Observe the pollen-masses ; at first they 

 are erect, but at the end of two or three minutes they incline forwards, 

 and if the pencil with the pollen-masses is placed in a second flower 

 they strike the stigma, and some of the pollen will adhere to it. 



The flowers of the Spotted Orchis are splendidly adapted for 

 cross-pollination, as the last experiment shows. The smallest 

 quantity of pollen will obtain the maximum of results. If a bed 

 of this plant is watched on a bright day in June or July, the 

 bees will be seen to work the flowers for food, and if some of 

 the insects are caught and examined the pollen-masses will be 

 seen to adhere to their heads. 



The Working of the Parts. The bee or other insect which is 

 attracted to the Orchid flower lands upon the labellum on the 

 lower side of the flower. He passes his proboscis down into the 

 spur in search of honey. The head of the insect thus comes in 

 contact with the rostellum, which gives way before the pressure 

 and the bee's head now rests against the anther. The base of 

 the pollen-masses comes in contact with the head of the insect 

 and begins to set there. This process requires time several 

 seconds at least. The time necessary for this to take place is 

 gained by the honey being stored up in the thickness of the 

 walls of the spur. To get the honey the proboscis has to dig and 

 penetrate the walls of the spur. This takes time, during 

 which the pollen-masses set on the head of the insect. When 

 the honey has been extracted, the insects fly away with the 

 pollen-masses, which change their position, as they did on the 



