SECT. II 



PHANEROGAMIA 



615 



dorsiventral flowers. K5, C3, A(8), G(2). The two lateral sepals are petaloid. 

 Three petals, the lowest of which forms a keel. Stamens 8, coherent into a tube. 

 Anthers opening by pores. Ovary bilocular, formed of two carpels ; a single ovule 

 in each loculus (Figs. 654-656). Polyyala chamaebuxus is a small shrubby plant 

 occurring in the Alps. P. vulgaris and P. amara occur in Britain. 



OFFICIAL. Polygala tieneya (North America) yields SENEOAE RADIX. 



Order 14. Trieoceae ( 31 ) 



The large Family of the Euphorbiaeeae which belongs to this 

 order is of much greater importance than the small family which is 

 here placed along with it. The plants belonging to the Euphorbiaeeae 

 are of very diverse 

 habit. The order in- 

 cludes herbs, shrubs, 

 leafless succulent 

 plants, trees with nor- 

 mal foliage, and others 

 with scale leaves and 

 assimilating phyllo- 



Kic.. 057. Ovule of Euphorbia 

 divica showing the obturator. 

 (Att'r PAX in Knglrr-J'runtl.) 



FIG. 658. Mercurialiti annua (i nat. si/.'). Male plant in 

 flower and single male flowei-. Portion of a female plant, 

 single female flower ami fruit. I'OISOXOUS. 



clades. The plants agree, however, in possessing unisexual, actino- 

 morphic flowers, with a simple perianth or with no trace of the 

 latter. Androecium diplostemonous or stamens numerous. The 

 female flowers are especially characterised by the superior, trilocular 

 ovary formed of three carpels ; in each loculus are one or two 

 pendulous ovules with a ventral raphe, and the micropyle directed 

 upwards arid outwards. 







The micropyle is covered by a placenta! outgrowth called the obturator (Fig. 

 657) ; this assists in conducting and nourishing the pollen-tube, and disappears 

 after fertilisation. The CARUNCULA, which is formed from the outer integument 

 (Fig. 662 D), persists on the other hand in the seed ; the separation of the latter 

 from the placenta is assisted by it. 



2 R 2 



