'.62 



BOTANY 



PART II 



here placed along Avith it. The plants belonging to the Euphorbiaceae 

 are of very diverse habit. The order includes herbs, shrubs, Jealless 

 succulentj)lants, trees with normal foliage, and others Avith scale leaves 

 and assimilating phylloclades. The plants agree, however, in possess- 

 ing unisexual, actinomorphic flowers, with a simple perianth or with 

 no trace of the latter. Androe- 



cium diplostemonous or stamens 

 numerous. The female flowers 

 are especially characterised by 



Fig. 540. — Diagram of a dicliasial branch of Euphor- 

 bia, with three eyatliia, only the middle one of 

 whieli has a fertile female flower. (After Eichi.er.) 



'^A- 



Fic. 539. — Euphorlia cypaHssius (g nat. .size). 

 Poiso/fOfS. 



Fio. 5-11.— Enphorhia resiiiifii-a. (\at. size 

 After Berg and Sch.mim. ) 



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 and outwards. 



The niicroiiyle is covered by a placental outgrowth called the obturator {Fig. 

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

 after fertilisation. The existence of the obturator on the ovule ma}' be regarded, 

 as marking a transition from the chalazogamic to the poroganiic fertilisation. The 

 CARUNCULA, whicli is formed from the outer integument (Fig. 542 D), persists on 



