CLASSIFICATION OF ANGIOSPERMS. 585 



in China and Japan and very hardy even in Northern Florida. 

 The fruit is round or oblong, from 3 to 5 cm. long and 2 to 3 cm. 

 in diameter, and of an orange-yellow color; the rind is sweet, 

 while the pulp is acid, and usually free from seeds, although from 

 i to 4 slightly beaked seeds may be present. 



The inner white portion of the rind of the Citrus fruits con- 

 tains a crystalline, tasteless glucoside known as hesperidin (see 

 pp. 151-154). Those which are bitter contain in addition several 

 bitter glucosides, namely, aurantiamarin and naringin. (See 

 Aurantii Amari Cortex, and Aurantii Dulcis Cortex, in Vol. II.) 



Volatile oils are also found in other members of the Rutaceae. 

 The garden rue (Ruta graveolens), the leaves of which are used 

 in medicine, contains a volatile oil consisting of several ketones. 

 It also contains a glucoside known as rutin which resembles the 

 barosmin of buchu ; and quercetin, which is said to be derived from 

 rutin. The Hop tree (Ptelea trifoliata) of Eastern North Amer- 

 ica contains besides a volatile oil, a resin and an alkaloid. The 

 volatile oil of pepper-moor (Zanthoxylum piperitum) of China 

 and Japan is known as Japanese oil of pepper. 



ANGUSTURA BARK obtained from Cusparia trifoliata or C. 

 officinalis, plants growing in the region of the Orinoco River, con- 

 tains a volatile oil, resin, a bitter principle and four alkaloids. 

 The wood of Amyris balsamifera of Guiana and Jamaica, yields 

 on distillation a volatile oil resembling Oleum Rhodii. 



h. SIMARUBACE;E OR AILANTHUS FAMILY. The 



plants are chiefly shrubs or trees with alternate and pinnately- 

 compound leaves. The flowers are regular, dioecious or polyg- 

 amous and in axillary racemes. The plants are natives of tropical 

 countries and are distinguished from the Rutaceae, which they 

 somewhat resemble by the absence of oil secretory cavities. They 

 are widely employed particularly in the tropics, on account of their 

 bitter principles, and are considered valuable tonics, febrifuges 

 and remedies for dysentery. 



Picrasma excelsa is a small tree with 9- to I7~foliate leaves, 

 the leaflets being ovate and more or less tomentose, particularly 

 in the bud ; the flowers are yellow, polygamous and in axillary 

 panicles ; the fruit is a large, spherical drupe. The wood of the 

 plant constitutes Jamaica quassia. 



