100 BOTANY. 



most of that India-rubber Avhich comes in bottles. Gum-lac is derived from 

 Aleurites laccifera, a Ceylon plant. 



Euphorbia officinarum, Spurge, Central and South Africa {pi. 11, ßg-. 9). 



Euphorbia cyparissias, Central Europe {pi. 71, ßg. 8) : a and b, flowers 

 of natural size and magnified ; c, pistil ; d and e, fruit of natural size and 

 magnified. 



Siphonia elastica, caoutchouc tree. South America {pi. 71, ßg. 10) : A, 

 branch with flowers ; a, a flower ; b, vertical section of ditto ; c, ovary in 

 cross-section ; d, ovary ; e, the ripe fruit. 



Order 56. Empetrace.e, the Crowberry Family. Flowers unisexual. 

 Perianth bud-like, consisting of persistent imbricated scales, in two or four 

 alternating rows, the inner row often petaloid. Male flowers ; stamens 

 two or three, equal in number to the scales in each roAV, and alternating 

 "with the innermost, hypogynous ; anthers roundish, dithecal, with longitudinal 

 dehiscence. Female flowers : ovary free, seated on a fleshy disk, three- 

 to six- or nine-celled ; ovules solitary, anatropal, ascending ; style one ; 

 stigma with as many radii as there are ovarian cells. Fruit, a nuculani- 

 um, seated Avithin the persistent perianth. Seeds solitary in each nucule, 

 ascending; embryo, in the axis of fleshy albumen ; radicle inferior. Heath- 

 like shrubs, with alternate or somewhat verticillate, evergreen, exstipulate 

 leaves. They inhabit chiefly Europe and North America. The fruit of some 

 is slightly acid. Empetrum nigrum, the black CroAvberry, is common on the 

 mountains and northern parts of Europe, and the United States. The fruit is 

 watery, and very slightly acid and astringent. Lindley notices four genera 

 and four species. Examples : Empetrum, Corema. Both these genera have 

 North American representatives. 



Order 57. Datiscace^, the Datisca Family. Flowers unisexual. Male 

 flowers : perianth three- or foui'-divided. Stamens three to seven ; anthers 

 linear, membranous, dithecal, Avith longitudinal dehiscence. Female flowers : 

 perianth adherent, three- or four-toothed. Ovary inferior, unilocular ; ovules 

 00, anatropal, attached to three or four parietal placentas ; styles, as many 

 as the placentas. Fruit, a one-celled capsule, opening at the apex. Seeds 

 00, strophiolate, Avith a reticulated spermoderm ; albumen ; embryo straight ; 

 cotyledons very short ; radicle pointing to the hilum. Herbaceous branched 

 plants or trees, Avith alternate, exstipulate leaves. They are scattered over 

 North America, various parts of Asia, and the south-eastern part of Europe. 

 Some of the plants are said to be bitter, and others of them have purgative 

 qualities. Lindley mentions three genera and four species. Examples : Da- 

 tisca, Tetrameles. 



Order 58. Rhizanthe.e, the Rhizogen Family. Flowers usually monoe- 

 cious or dioecious, sometimes ? . Perianth more or less perfect, superior, 

 trimerous, tetramerous, or pentamerous ; sometimes obsolete or 0. Stamens 

 united, often in a fleshy column, to Avhich the anthers cohere, dithecal, 

 extrorse, opening longitudinally or by pores. Ovary inferior, one- or two- 

 celled ; ovules definite or 00. Fruit indehiscent, pulpy, usually unilocular. 

 Seeds, sometimes solitary and pendulous, at other times 00, and attached to 

 100 



