47 



Poa nemoralis the median lines are most noticeable 

 near the apex of the blade. The median lines are a 

 pair of furrows which mark off a flat mid-rib. Cocks- 

 foot, though a ribless bladed grass, does not belong to 

 this group, because the median lines are wanting. 



Triodia, at first sight, seems to belong to this group, 

 but close inspection shews that the blade has low, 

 flat, and very broad ribs. It is, therefore, assigned to 

 the next group. 



Group XI I L Low (Flat) Ribbed Hairless 

 Grasses, Page 72. 



As a rule, the members of this group are immedi- xm. 10. 

 ately identified by a naked-eye examination of the 

 upper surface of the blade. At times Phleum has 

 rounded, rather than flat, ribs. The sheath should be 

 noted to see that hair is absent. Short hair is most 

 readily detected by looking along, not at the surface. 



Group XIV, High (Acute or Round) Ribbed 

 Grasses. Page 73. 



This group includes the species with prominent 

 ribs ; in Agrostis, the ribs are least prominent. 

 Although well-marked ribs are usually acute, they 

 may at times be even rounded or decidedly flat at the 

 summit. To determine this point, the blade ought 

 to be cut across, midway between apex and base, and 

 the section examined by a lens. 



