1 70 ORCHIDACE&. [CHAP. 



ORCHIDACE.E. 



This order is the subject of Mr. Darwin's admirable 

 work, " On the Various Contrivances by which British 

 and Foreign Orchids are fertilised by Insects," from 

 which the following facts are taken. The order con- 

 tains sixteen British genera, several of them extremely 

 curious and pretty. The species with long nectaries 

 are fertilised by Lepidoptera, those with shorter ones, 

 as a general rule, by bees and flies ; Epipactis latifolia, 

 it is said, exclusively by wasps, so that, according to 

 Darwin, " if wasps were to become extinct in any 

 district, so would the Epipactis latifolia" Other 

 species on the contrary such as Epipactis viridifolia, 

 and Ophrys apifera (the Bee Orchis) habitually 

 fertilise themselves. It is remarkable that in some 

 Orchids the ovules are not developed until several 

 weeks, or even months, after the pollen tubes have 

 penetrated the stigma. (Hildebrand, Bot. Zeit., 1863 

 and 1865. Fritz Miiller, Bot. Zeit. t 1868.) 



The flower in this order is very abnormal. There 

 is, except in Cypripedium, only one anther, which 

 is confluent with the style, forming the so-called 

 "column." The anther is divided into two cells, 

 which are often so distinct as to appear like two 

 separate anthers. The pollen in most Orchids co- 

 heres in masses, which are supported by a stalk 

 or " caudicle ; " the pollen masses with their stalks 

 are called "pollinia." The styles are theoretically 

 three in number ; but the stigma of the upper one 

 is modified into a remarkable organ called the 



