402 SYSTEMATIC BOTANY 



a white stalk, but this if cut across is seen to be 

 really a long inferior ovary with three cells. It 

 is deeply ribbed on the outside and the ribs show 

 a twist as if the ovary were twisted on its axis half 

 way round. Looking at the flower in front we see 

 five petals or sepals and a white central part from 

 which sticks out forward a bluish brown petal, the 

 bottom or back of which is a tube (the 'spur'); this 

 with the five others making up the six perianth seg- 

 ments which we find to be the rule among monocoty- 

 ledonous plants : so that of the five petal-like segments, 

 the one at the top and the two lower lateral ones, are 

 sepals and the other two petals. The blue or brown 

 front petal which stretches out forward and is spurred 

 behind is termed the labellum. On each side of and 

 attached to it are two pointed lobes and above, on 

 the centre of the flower, is a thick solid column. At 

 the top of the column is a thin white cap shining 

 through which one can see two yellow golden masses 

 of pollen (polliniums), and if this cap be taken off 

 it will be found to have on its under side two little 

 pockets which enclosed the two polliniums. 



In the ASCLEPIADACE^ (p. 352) there are two 

 pockets containing polliniums, which though widely 

 separated made up, as we saw, one anther. In VANDA 

 (and Orchids generally) the cap with its two pockets is 

 part of one much modified anther. From the front, 

 basal end, of each pollinium extends a thin white thread 

 which is connected to a comparatively broad strap 

 .attached to the front edge of the column. If a needle 

 or pencil be pushed up gently against the flap at the 

 top of the face of the column, the latter, being sticky, 



