310 



PHYLUM XIV. AXTHOPHYTA 



Fig. ISS.— Opunti 



eventually splitting open to permit the escape of the 

 seeds. 



570. The flower of the Prickly Pear (Opuntia, a cactus) 

 is in plan much like the preceding, but there are more 

 carpels (four to eight) : these are united at their margins, 



so that there is- but one, many-ovuled 

 cavity, with four to eight parietal 

 l^lacentae. The cup is ver}- fleshy, and 

 bears on its margin and inner face the 

 very many stamens, many petals and 

 many sepals. Cactuses are evidently 

 related to the Evening Primroses, but 



are peculiar in being very fleshy, and mostly leafless. 



The stems of the Prickly Pear when young bear small 



leaves, but these soon dry up and fall off after which the 



stems are leafless. 



571. The Walnut flowers (Juglans) are small and 

 diclinous, those with stamens being in drooping, cylindri- 

 cal, crowded clusters, those with 



pistils soUtary or in pairs. Staminate 



flowers with a reduced perianth 



(calyx), and many short stamens; 



pistillate flowers with a bicarpellary Fu-.. is9.— Jugians. 



pistil which is wholly covered with 



the thick cup, on the margin of which are four reduced 



sepals, and as many very small petals. The fruit is fleshy 



externally while the single seed is surrounded by a mass 



of stone tissue, as in the plum. 



572. The flowers of the Oak (Quercus) are much like 

 those of the Walnut, but the staminate flower clusters 

 are less dense, and the pistillate flowers are solitary in scaly 

 involucres (i.e. a collection of several to many crowded 

 bracts). The staminate flowers have a reduced perianth 

 (calyx) and six to twelve long stamens, while the single 



