ii8 THE STRUCTURE OF ECONOMIC PLANTS 



their first differentiation cycle are not to be accepted as an explana- 

 tion of the real nature of such individuals." On the other hand, 

 McPhee (x}) notes that "sex determination in hemp can be ex- 

 plained on a genetic basis, and that the inheritance is of the XY 

 type." 



The Staminate Inflorescence and Flower. — The staminate 

 flowers develop in small, drooping, branched panicles, which 



Fig. 103. Habit of carpellate flowers of hemp. (Reproduced from Yearbook of U. S. Dept. 



of Agriculture , 1913.) 



arise in the axils of foliage leaves. (Figs. loi. and 104, y4.) The 

 flowers of the panicle may occur singly on slender pedicels or in 

 groups, and usually the terminal branches bear three flowers, a 

 median one and two laterals which are subtended by bracts or 

 stipules. (Fig. 104, 5.) The individual flowers are apetalous 

 with a deeply parted calyx having five greenish-yellow or red 

 lobes that are widespread at maturity. There are five stamens, and 

 the anthers are suspended from long thread-like filaments. (Fig. 

 104, C.) The plants are wind pollinated, and large numbers of 



