1750 A TEXTBOOK OF THEORETICAL BOTANY 



In the genus Brosimiim the akenes are embedded in a fleshy receptacle 

 which in B. alicastrum is used for food in the West Indies under the name 

 of Bread-nut. B. galactodendron is the Cow-tree of Venezuela. The milky 

 latex flows in considerable quantity and tastes very like ordinary milk and 

 is used for that purpose by the natives. Several other species have useful 

 wood, known as Snake Wood. 



Broussonetia papyrifera, the Paper Mulberry of Japan, is used by the 

 Polynesian natives to make Tapa or Kapa cloth. It is obtained from the 

 inner bark. Sheets of this, prepared with the flbres crossed, are beaten 

 together make a tough fabric. 



Antiaris toxicaria is the famous Upas Tree of Java. The latex contains a 

 very virulent poison and a century ago extraordinary stories of its effect 

 were told. It was said that for a distance of several miles around the tree 

 nothing could live. The noxious volcanic valleys with a high carbon dioxide 

 content in the air were probably responsible for these stories. 



Castilloa elastica, Ulc, is a native of Cuba. It yields caoutchouc and is 

 the source of the Central American or Panama rubber. 



Finally mention must be made of the genus Cecropia of which some 

 forty-five species occur in tropical America. They are of particular interest 

 because of the symbiotic association established between these trees and 

 certain species of ants which inhabit the hollow stems. C. peltata (Fig. 

 1628) is the Trumpet Tree, so called because of the use made of its hollow 

 stems by the Indians of Brazil. 



The fourth family of the Urticales is the Cannabinaceae. It is a small 

 family containing only two genera, Humulus and Cannabis, which are 

 included by some writers in the Moraceae. They differ however from that 

 family in having no latex. The plants are dioecious, and the flowers occur 

 in cymose inflorescences, which contain many male or few female flowers. 

 The male flower has a five-parted perianth and five opposite stamens, while 

 the female flower has a small cuplike perianth and a unilocular ovary con- 

 taining a single pendulous ovule. The embryo in Humulus is coiled while in 

 Cannabis it is curved. 



The genus Humulus contains two species, both of which are climbers. 

 H. lupuhis (Fig. 1629) is the Hop, which is widely cultivated. In this 

 country Hop gardens are found particularly in Kent and Herefordshire. It 

 is a perennial and in rich soil the shoots, generally called bines, grow to a 

 height of 20 to 30 ft. in a year. Those used in commercial cultivation are 

 varieties and are known by such names as Goldings, Grapes or White 

 Blues. The bracts bear numerous yellow glandular hairs which secrete 

 lupulin, an aromatic substance of a resinous nature to which they owe their 

 value for flavouring beer. The Hop is wild in Europe and North America. 



The second species, H. japonicus, is a native of China and Japan. It 

 bears no lupulin glands and hence is of no economic value. It is cultivated 

 as a decorative plant in gardens. 



The genus Cannabis contains the single species C. sativa, Hemp 

 (Fig. 1630). It is an annual plant, a native of central Asia. It is now widely 



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