PETALOIDE.E 293 



3-valved loculicidal capsule. Seeds extremely minute, 

 exalbuminous, with a minute undifferentiated embryo. 



This is a large family of wide distribution. Cool 

 and moist regions, especially shady forests, are their 

 favourite grounds. They are abundant in the cool, 

 moist, hilly forests of Assam and Darjiling. In the 

 epiphytic species the cortex of the root is covered 

 with a special epidermis called the velamen, which 

 is several layers of cells in thickness, and thus facili- 

 tates the absorption and conduction of water-vapour 

 as well as rain and dew (an instance of adaptation to 

 environment). The Orchids are distinguished by a 

 greater variety of flower-forms than any other family 

 of plants, and these forms are adapted in a remarkable 

 way for cross-pollination, so much so that the structure 

 of a flower corresponds in its smallest details to the 

 peculiarities of the form of its insect-visitor. Auto- 

 matic self-pollination is usually excluded by the 

 relative position of the stigma and the anther. The 

 flowers are pre-eminently bee-flowers. 



A bee, attracted by the bright-coloured perianth, 

 comes and sits on the labellum as on a platform, 

 and directed by the nectar-guides moves towards the 

 opening of the perianth-tube leading to the honey 

 concealed in the spur of the labellum. In so doing 

 its forehead comes in contact with the rostellum, which 

 is so fragile that it breaks, and the pollinia together 

 with the retinaculum fall off from the anthers and 

 stick to the forehead of the bee (see figs. 102, no). 

 By the time the bee, leaving the flower after sipping 

 its honey and taking the load of pollinia on its fore- 

 head, comes to sit on the labellum of another flower, 

 the pollinia on its forehead, by the bending of the 

 caudicles, point exactly towards the receptive stigma 

 of the second flower, and touch the latter as the bee 



