130 MYSTERIES OF THE FLOWERS 



beyond which no progress is further possible. The 

 union of stamens and pistils into the column is, 

 then, the distinguishing mark of the orchid ; but, in 

 addition to this, we know that all orchids have leaves 

 with parallel veins, and their flowers are so organ- 

 ised as to depend, with rare exceptions, exclusively 

 upon insects for their fertilisation, and, in some 

 cases, upon one insect affinity in particular. 



The pollen of the orchid also is different from 

 that of most other plants. It is seldom the dry 

 and powdery substance we are familiar with, but 

 is usually waxy and is often made up into club- 

 shaped masses, or into globules bound together with 

 minute threads. 



Now, many people suppose that the orchids are 

 necessarily "air plants" and that they are very 

 tender and costly flowers from the tropics. It is 

 easy to see that these ideas, true to a certain extent, 

 were propagated in close and humid hothouses 

 along with the gaudy exotic orchids flourishing 

 there. 



It is true that the tropical conditions favour and 

 breed a very large number of orchids, many of 

 which are, indeed, air-plants; but, on the other 

 hand, there are orchids adapted to every clime and 

 condition, latitude and altitude, making them the 

 most widely distributed family in the floral king- 



