III.] ORCHID A CEM, 3 1 7 



An epiphytal herb, cultivated in gardens, with pendulous 

 branches, emarginate leaves, and beautiful pale-sulphur or 

 white and rose-coloured irregular flowers, with a purple eye. 



Fig. 20I. Flower of Dendrobitim nohile, natural size. 



The three outer leaves of the perianth are often called 

 sepals, and the three inner leaves petals, in this Family. 

 Of the three inner leaves, two are lateral and equal, and one 

 (usually the lower one from the twisting of the ovary) different 

 in form, often much larger than the sepals and lateral petals, 

 sometimes lobed and jointed, sometimes very small. This 

 odd petal is called the labellum. It is sometimes provided 

 with a spur at its base containing nectar, much sought after 

 by insects ; the visits of which are in many cases absolutely 

 necessary, in order that the flowers may be fertilised and 

 good seed produced. 



Compare the structure of the anther and pollen of Den- 

 drobium with that of the Sub-types — 



