January, igiO.] 



THE ORCHID WORLD. 



«i 



THE STRUCTURE OF AN 

 ORCHID FLOWER. 



"'^ I ^HERE is no order of plants," wrote 

 I Dr. Lindley, " the structure of 

 whose flowers is so anomalous as 

 regards the relation borne by the parts of 

 reproduction, or so singular in respect to the 

 form of the floral envelope. Unlike other 

 endogenous plants, the calyx and corolla are 

 not similar to each other in form, texture and 

 colour ; neither have they any similitude to 

 the changes of outline that are met with in 

 such irregular flowers as are produced in other 

 families of the vegetable kingdom. On the 

 contrary, by an excessive development and 

 singular conformation of one of the petals 

 called the labellum or hp, by irregularities 

 either of form, size, or direction of the other 



Dendrohium Farmeri. 



sepals and petals, by the peculiar adhesion of 

 those parts to each other, and by the 

 occasional suppression of a portion of them, 

 flowers are produced so unusual and so 

 grotesque in form that it is no longer with 

 the vegetable kingdom that they can be 

 compared, but we are forced to seek 

 resemblances in the animal world." 



But notwithstanding this apparently endless 

 variety in form, a general plan of floral 

 structure pervades the whole family of 

 Orchids that clearly distinguishes it from 

 every other natural order of plants. The 

 floral organs are constructed upon a 

 trimerous type, that is to say, all the parts 

 are in threes or a simple multiple of three ; 

 but owing to the suppression of some, the 

 confluence of others, and various other 



Odonloglossum cilrosmum. 



modifications, especially of the sexual organs, 

 the trimerous condition, except in the two 

 series of perianth segments, is greatly 

 disguised, but it is, nevertheless, almost 

 always present. 



Irregular as the flowers appear on super- 

 ficial view, there may always be detected in 

 them a bilateral symmetry, that is to say, all 

 normally developed Orchid flowers may, in 

 one direction only, be divided in a monosym- 

 metrical mjinner or into two equal parts that 

 resemble each other in every particular. 



Renanthera coccinea. 

 With dissimilar dorsal sepal. 



VOL. VI. 



12 



