THE YAM FAMILY. 



165 



This is also a native of Chili, and has a variety (L. rosea v. 

 alba) with pure white waxy flowers. 



Another singular climbing plant of this alliance is JRocc- 

 lurghia gloriosoides, a native of India, and which is by some 

 botanists placed in a distinct family — Roxhurghiacece. 



Another small family of about 30 species, Trilliacece^ is 

 also allied, and is chiefly represented by the genera Trillium 

 and Paris, which consists of perennial herbaceous plants, 

 with whorled leaves, bearing terminal flowers, and are chiefly 

 natives of temperate countries, many of North America. 

 In this country they are represented by Paris quadrifolia, 

 found on the outskirts of woods, but rare. Its roots are of 

 a poisonous nature, and the plant is popularly known as 



Herb Paris." 



The Yam Family. 



(DlOSCOEEACE^.) 



Plants with solid, fleshy, underground tubers, or woody 

 above-ground corms, and producing climbing stems, which 

 are slender, and either perennial or herbaceous. Leaves 

 alternate, rarely opposite, more or less heart-shaped, with 

 well-marked longitudinal veins, which anastomose laterally. 

 Flowers small, produced in loose, pendulous spikes, and 

 generally unisexual. About 150 species are enumerated as 

 belonging to this family, all being widely distributed through- 

 out the tropics, and represented in this country by Black 

 Bryony {Tamus communis). An acrid principle is contained 

 in most of the species, some even being poisonous, but culti- 

 vation renders them harmless. 



Yam (Dioscorea sativa, D. aculeata, and several other 

 species), are natives of India and other warm countries of the 

 East, where they are extensively cultivated and take the 

 place of the potato of more temperate climes. There are 

 many varieties varying in size and quality, but all contain 

 more or less of a nutritive farina. The yam was early intro- 

 duced to the West Indies, where it forms a great part of the 



