CuAP. VI. STKUCTURE OF COLUMN. 149 



CHAPTER yi. 



VANDE.E. 



Structure of the eolumu and polliiiia — Importance of tlie elasticity of 

 the pedicel ; its power of movement — ^Elasticity and strength of the 

 caudicles — C'alauthe with lateral stigmas, manner of fertilisation — 

 AngrsBcum sesquipedale, wonderful length of nectary — Species with 

 tlie entrance into the stigmatic chamber much contracted, so that 

 the pollen-masses can hardly be inserted— Coryanthes, extraordinary 

 manner of fertilisation. 



We now come to the immense tribe of the Vandeae, 

 which includes many of the most magnificent produc- 

 tions of our hothouses, but like the EpidendresB has 

 no British representative. I hare examined twenty- 

 nine genera. The pollen consists of waxy masses, as 

 in the two last tribes, and each ball of pollen is 

 furnished with a caudicle, which becomes, at an early 

 period of growth, united to the rostellum. The cau- 

 dicle is seldom attached directly to the viscid disc, as 

 in most of the Ophreae, but to the upper and posterior 

 surface of the rostellum ; and this part is removed by 

 insects, together with the disc and pollen-masses. The 

 sectional diagram (fig. 23), with the parts separated, 

 will best explain the type-structure of the Vandeae. 

 As in the rest of the Orchidea there are three con- 

 fluent pistils; of these the dorsal one (2) forms the 

 rostellum arching over the two others (3) which unite 

 to form a single stigma. On the left hand we have 

 the filament (1) bearing the anther. The anther opens 

 at an early period, and the tips of the two caudicles 

 (but only one caudicle and one pollen-mass are re- 



