THE SWALLOW- WORT FAMILY. 



293 



a central more or less elevated 5-sided corona, bearing 5 

 stamens, each consisting of two separate masses of pollen 

 attached to a gland. Stigmas 2, generally covered with the 

 corona, which has 5 vertical slits or pores in its sides, 

 through which the pollen reaches the stigmas (fig. 4, c and 

 d). Fruit generally in two distinct follicles, compactly 

 packed v/ith seeds, furnished with fine silky hairs. 



Nearly 1000 species constitute this family. They are of 

 remarkable diversity of form, and generally abound within 

 or near the Tropics; a great number being natives of dry 

 arid places in South Africa, chiefly consisting of the succulent 

 and leafless genus Stajielia, the tuberous stemmed Brachystelma 

 and such like plants. In India and the Malayan Islands they 

 are represented by climbing Hoyas, Ceropegias, Stepha?iotis, 

 &c. ; in Tropical America by Gonolohus ; and in north tempe- 

 rate regions by Asclepias Cynanclium and the climbing 

 Feriploca of the South of Europe. 



The principle of the family is on the whole acrid and 

 poisonous, but in some cases the milk is said to be harmless ; 

 many, however, have great reputation in their respective 

 countries for their medical virtues, such as Tylophora asth- 

 ■niatica, the roots of which are substituted in India for 

 Ipecacuanha. 



Gymnema sylvestre. A tree, native of the northern part 

 of India, having thick fleshy leaves, which, when chewed, 

 have the singular effect of destroying the taste of sugar, 

 making it feel like sand in the mouth. The most important 

 products of the family are fibre and caoutchouc. Many are 

 cultivated, and much admired in the hothouses of this coun- 

 try, such as Stephanotis Jloribunda, Hoya car?iosa, H. im- 

 perialism several species of Ceropegia, and numerous species of 

 Stapelia, the flowers of the latter being fleshy and having 

 the odour of putrid meat (see page 52). 



Muddar (^Calatropis gigantea). A shrub or small tree 

 about 15 feet high, native of India, yielding a fibre equal to 

 hemp, and a kind of gutta-percha is obtained from its milky 

 juice. C. procera is abundant in the valley of the Dead Sea, 



