28 



GRASSES OP IOWA. 



bundles of the mid-nerve. Two bundles of the third type 

 occur near the margin of the leaf. The cells separating the 

 leptome from the stereome are in this case somewhat thicker - 

 walled than those in the mid-nerve. 



The mestome bundles of second type are of two sizes, the 

 largest ones having leptome and hadrome poorly developed, 

 and the smallest having no thick-walled cells. 



:bc. 



Fig. 22. Section of leaf of Leer»ia oruzoiden Schwartz. JiC, buUlform cells; portion 

 of mid-rib In section; MS, mestome sheath; P, parenchyma; S, sclerotic cells. (Holm.) 



The thin- walled parenchyma, with its inner closed sheath 

 does not differ from that of Festvca 2Jratensis and Lolium j^erenne. 

 Stereome seems to be more strongly developed in this species 

 than in Festuca elatior, var. 'pratensis and Lolium perenne. It 



