DICOTYLEDONES—DISCIFLOR^ 



313 



tropical America. Illustrative Cenera : — Oxalis, Linn. ; Aver- 

 rhoa, Linn. There are about 330 species. 



Proijerties and Uses. — Chiefly remarkable for their acid juice, 

 which is due to the presence of binoxalate of potassium. The 

 fruits of some are eaten by the natives in the East Indies, but 

 they are too acid to be generally acceptable to Europeans. 



Order 95. RutacEjE, the Hue Order. — Character. — Trees, 

 shruhs, or rarely hcrhs. Leaves exstipulate, simple or compound, 

 dotted. Flowers perfect or polygamous, regular. Calyx having 

 3 — 5 segments, imbricate. Petals equal in number to the 

 divisions of the calyx or wanting, rarely combined so as to form 

 a gamopetalous corolla ; cesfivatinn usually twisted, rarely val- 



FiG. 1084. 



Fir. 1085 



Fifi. 1086. Fm. 1087. 



Mg. 1084. Diagram of the flower of the Orange (^f'i/rus Aurantiitm). Fi:/. 



1085. Vertical section of the pistil, showing a portion of the disc ;it its 



base, and a solitary hypogynous stamen. Fig. 1086. Pistil of the Orange, 



v.'ith disc at its base, and the calyx ; the petals and st.imens have been 



removed. Fig. 1087. "Vertical section of the seed of tlie Common Bue 



(li'ila graveoJens). 



vate. Stamens distinct, or more or less united into one or 

 several bundles, equal in number to or twice as many as the 

 petals, or some multiple of them, or rarely fewer by abortion. 

 Disc annular or cup-shaped, glandular, hypogynous. Ovary 

 sessUe, or raised on a gynophore ; it is composed of from 2 to 5 

 carpels, which are either distinct or united so as to form a com- 

 pound ovary having as many cells as there are component 

 carpels ; style simple or divided towards the base ; ovules 2, 4, 

 or rarely more in each cell. Fruit capsular, its carpels either 

 united or more or less distinct, or succulent and indehiscent, 

 and in Ani-antiece forming a hesperidium. Seeds solitary or in 

 pairs ; albumen present or absent ; radicle superior. 



Diagnosis. — Leaves exstipulate, dotted. Flowers perfect 



