56 



Ligule conspicuous. Bristle very hard and very stiff. 

 Nardus stricta, L. (Moor mat grass), Ligule thick and 



obtuse. See commencement of group. 

 Bristle solid (fig. 9). A transverse section immedi- 

 ately determines whether the bristle is solid or 

 not. 



Aira flexuosa, L. (Wavy hair grass). Section of 



bristle heart-shaped. 



Fig. 8. Blade, sheath, and ligule. After Lund. 

 Fig. 9 and 10. Transverse section of the bristle 



(magnified). After Lund. 



NOTE. In other Aira species the bristle is formed by 

 folding or inrolling of the blade. 



Bristle covered with short, stiff, grey hair. 



Aira canescens, L. (Grey hair grass). 

 'Bristle very glaucous ; sheath very flat and broad. 



Aira uliginosa, Weihe. (Bog hair grass). 

 Bristle very blunt pointed. 



Aira prsecox, L. (Early hair grass). An annual. 

 Blade soft and succulent ', concave and bristle like. 



Poa maritima, Huds. L (Creeping sea meadow grass). 

 The succulent blades have all the characters of Poa 

 (except the keel], i.e. they are ribless with median 

 lines. Ligule obtuse. 



Fig. II. A shoot with the bristle-like blades. 

 Fig. 12. Side view of base of blade and ligule (mag- 

 nified). After Lund. 

 Fig 13. Front view of the same (magnified). After 



Lund. 



Fig. 14. Apex of blade (magnified). 

 Fig. 15. Transverse section of blade (magnified). 

 Observe the thickness, absence of ribs 

 and keel, and the median lines. 

 Fig. 16. Portion of blade (magnified) viewed from the 



upper surface, shewing the median lines. 

 Fig. 17. Transverse section of folded blade (magnified). 



After Lund. 

 Fig. 18. Portion of mature blade (highly magnified). 



After Lund. 

 Blade comparatively thin, dry, and keeled. 



Avena pratensis, L. (Glabrous oat grass). The dry 

 blades have all the characters of Poa, i.e., they are 

 ribless, have median lines, and a prominent keel 

 Ligule with an abrupt ^ acute point. 



