564 



BOTANY 



PART II 



are usually groujied in dichasia, and these in turn form an umbellate inflorescence, 

 with three to many branches. It often happens that the female flower is only 

 developed in some of the cyathia, remaining rudimentary in the others. ]\Iany 

 species of Euphoi-bia, especially the African species, are succulent-stemmed plants 

 _resembling i'luii in i^fueral appearance (cf. Fig. 541). 



EupJiorhiu, like many but not all the other plants of the family, contains a 



Fio. bii.—Ricirms com,innni$, greatly reduced. (After Baillon.) l'u/so.\ors and Ofj-vc/a/,. 



milky juice, which is secreted in uon-septate latex-tubes. This juice, which in 

 many cases is poisonous, exudes wherever the plant is wounded. 



An important constituent of the latex of species of Ilevea {H. Sieheri, discolor, 

 rigidifolia, ijaucifolia, lutea, yuyanensis, Sprucetma) is caol'TCHOUC. As Para 

 Rubber obtained in the tropics of South America, especially in the Amazon Region, 

 this affords about one half of the total rubber sup])ly. In addition Manilwt 

 Glaziovii, another South American plant of this order, which yields Ceara Rubber, 

 must be mentioned. A nearly related plant, Manihot utilisshtm, provides in its 

 tuberous roots a very important food in the tropics. The starch obtained from 



