CLASSIFICATION OF ANGIOSPERMS. 583 



capsule. The leaves of three species are ofhcial as Pilocarpus 

 or Jaborandi. 



Barosma. — The buchu leaves of medicine are obtained from 

 several species of Barosma (see Vol. II). The plants are branch- 

 ing shrubs with opposite, coriaceous, serrate or dentate leaves 

 with glandular margins ; the flowers are white or reddish and occur, 

 I to 3, in the axils of the leaves; the fruit is a 5-valved capsule. 

 The leaves contain a volatile oil, one of the constituents of which 

 is diosphenol. 



Citrus. — The fruits of a number of species of this genus are 

 edible, and the plants are also valued for their volatile oils. They 

 are aromatic, glandular, mostly thorny shrubs or small trees 

 indigenous to tropical and sub-tropical Asia, and now extensively 

 cultivated in tropical, sub-tropical and warm-temperate regions. 

 The leaves are more or less winged-petiolate, glaucous, coria- 

 ceous, mainly unifoliate (or trifoliate) ; the flowers are complete, 

 with a 3- to 6-toothed gamosepalous calyx, and 4 to- 8 glandular 

 petals ; the stamens are 20 to 60, in groups of i to 9 ; the ovary 

 is subtended by a cushion-shaped disk, and the fruit is a spher- 

 ical, oblong or pear-shaped berry, having a coriaceous pericarp 

 with numerous lysigenous oil-glands, a juicy pulp made up of 

 peculiar hair-structures which arise from the endocarp, and in 

 which are embedded white polyembryonic seeds (Fig. 280, C). 



Botanists have divided this genus into two sub-groups: (a) 

 the Pseudo-^gle group is represented by the trifoliate orange 

 (Citrus trifoliata), cultivated widely in the United States as a 

 hedge. The leaves are trifoliate and deciduous, the petals spatu- 

 late and the ovary and disk hairy, {b) In the Eucitrus group the 

 leaves are unifoliate and evergreen, the petals oblong, and the 

 ovary and disk glabrous. This latter group includes the two 

 species which yield most of the edible Citrus fruits. 



Citrus Aurantiiun includes a number of sub-species and varie- 

 ties. The plants are small trees with leaves having winged 

 petioles ; fragrant, white flowers ; and a more or less globular 

 fruit. The Sweet Orange (Malta, Portugal) is derived from the 

 sub-species sinensis. The Bitter Orange (Seville, Curasao) 

 is derived from the sub-species auiara. The flowers of both the 

 Sweet and Bitter Orange tree contain a volatile oil known as Oil 



