332. 



THE STRUCTURE OF ECONOMIC PLANTS 



able, depending upon the variety of alfalfa and, to some degree, 

 upon cultural practices and climatic conditions. Garver (ix) has 



— xy 2 



-^^xy 1 



Fig. 167. Transection of sector of old stem: ca, cambium; col, coUenchyma; en, endo- 

 dermis ; ep, epidermis ; par, cortical parenchyma ; pel, pericycle ; ph, phloem ; pi, pith ; 

 xy I, primary xylem ; xy i, secondary xylem. 



pointed out that most of the southern-grown forms have relatively 

 few rooting rhizomes; while in the northern-grown, variegated 

 alfalfas, especially Grimm, the rhizomes are often well devel- 



