Net sheathed aquatics Catabrosa^ Glyceria. (See VI.) 



Catabrosa aquatica, Beauv. (Water- whorl grass). Ligule 

 with a rounded apex. 



Fig. 5. Apex of blade. 



Fig. 6. Base of blade and ligule. 



Fig. 7. Transverse section of folded blade (magnified). 



Glyceria aquatica, Sm. (Reed sweet grass). Ligule with 



an abrupt, acute point. 

 Fig. 8. Apex of blade. 

 Fig. 9. Base of blade and ligule. 

 Fig. 10. Transverse section of blade. 

 Fig. 1 1 . Transverse section of two-edged sheath. 



Dry-bladed grasses Avena species. 



Avena pubescens, L. (Downy oat grass). Sheath clothed 

 with conspicuous downy hair; its edges acute. 



Fig. 12. Apex of blade. 



Fig. 13. Hairy sheath, base of blade, and ligule. 



Fig. 14. Transverse section of blade (magnified). After 

 Lund. 



Fig. 15. Transverse section of two-edged sheath (mag- 

 nified). After Lund. 



Avena pratensis (Glabrous oat grass). -Ligule with an 

 abrupt acute point. Margins of blade thorny. Sheath 

 stiff and elastic. 



Fig. 16. Apex of blade. After Lund. 



Fig. 17. Base of blade. Observe the rough margins 

 and apex of ligule. After Lund. 



Fig. 18. Transverse section of blade (magnified). Ob- 

 serve the thickness. After Lund. 



Fig. 19. Transverse section of sheath (magnified). 

 After Lund. 



