INTRODUCTION xxiii 



and 8, which is a type of the structure of several genera, the 

 lip has a slender curved tube hanging from the point where it 

 joins the ovary. This is called the spur. It is generally filled 

 with nectar, and as the insect alights on the lip, which serves 

 as the threshold of the flower, the opening to the spur lies 

 directly in front of him and under the stamens and 

 stigma. 



As a near relative of the lilies and irises we expect to see 

 the stamens and pistils separate from one another, arranged 

 in threes; but in order to concentrate their efforts at the 

 opening of the flower through which the insect approaches 

 its heart, the stamens and style have grown together into one 

 organ called the column. Thus one stalk bears the stigma 

 and the pollen. We can trace the metamorphosis in Plate I., 

 Figs. 5 and 6. 



This growing together of the reproductive organs is the 

 feature that distinguishes the orchids from all other monoco- 

 tyledons. The pressed together, knobby, almost grotesque 

 structure with curiously packed pollen grains in the centre 

 of the flower is the characteristic sign by which the novice 

 may know that he has found an orchid (Plate I., Figs. 9, 

 10, II, 12, 13). 



The structure of the column is various. In some cases, 

 as in the Lady's-Slipper, there are three anthers, two 

 fertile, packed with pollen masses, on either side of the 

 stigma, and one sterile, like a pointed leaf hanging over the 

 stigma. In other cases there is but one anther containing 

 two pollen sacs, one on either side of the stigma. Sometimes 



