THE ORCHID FAMILY. 255 



Although the structure is the same in all orchids 

 but one genus (not in South Africa), there is an infinity 

 of shapes and corresponding adaptations to insects. In 

 many the ovary or its pedicel is so greatly twisted 

 that the flower is completely reversed in position, so 

 that the labellum, which we have seen is really the 

 posterior petal (since it is on the side of the flower 

 opposite to the position of the bract), actually becomes 

 the front petal, and then grows out into a large one to 

 receive the insect as its resting-place. In Pterijgo\lium, 

 of which there are some ten species in South Africa, 

 the lip is in front, and forms a slipper-like structure. 



The structure of the ovary should now be observed. 

 By cutting it down, it will be found to be one-celled, 

 but with three large parietal placentas projecting 

 inwards, and carrying an immense number of ovules 

 (V.). When some of these are fertilized, the fruit forms 

 a capsule, which, when ripe, bursts by three valves, 

 leaving a framework behind (VI.). The seeds are very 

 minute and imperfect, consisting of a loose skin with an 

 undeveloped embryo within it (VII.). 



It not infrequently happens that, when plants are 

 habitually propagated by underground tubers, bulbs, 

 etc., they seem to lose the power of setting seed by 

 their flowers. Such is the case with the garden Horse- 

 radish, the species of Cro'cus cultivated for saffron, 

 which consists of the dried style and stigmas, and with 

 a very common species of Ramm'culns in England, 



