GRASSES OF SCOTLAND. 5 



* * * Cah/x containing two Florets. * 

 27. ^lELICA. — Florets without awns, not longer than the calvx. 

 Outer palea seven-ribbed. Two species. (Plate XVm.) 



29. AIROCHLOA. — Florets without awns, not longer than the 

 calyx. Outer palea three-ribbed. One species. (Plate XTX.) 



31. MOLIXIA. — Florets without awns, much longer than thecah"x. 

 Leaves hairy on the inner surface. Two species. (Plates XIX. 

 XX.) 



32. CATABROSA. — Florets without awns, much longer than the 

 calyx. Leaves not hairy. One species. (Plate XX. ) 



33. HOLCUS. — Upper floret awned from a little beneath the sum- 

 mit ; the lower floret mostly not awned. Calyx longer than the flo- 

 rets. Two species. (Plates XXL XXH.) 



35. ALRA. — Florets awned from beneath the centre. Glumes of 

 about equal lengths. Five species. (Plates XXTII. XXIX'. XXV.) 



40. ARRHENATHEROL— Lower floret awned from a little 

 above the base ; the upper floret from a little beneath the summit. 

 Glumes very unequal One species. (Plates XXV. XXAT.) 



41. AVEXA. — Florets awned from a little beneath the centre. 

 Glumes not less than seven ribbed. Two species. (Plates XX VL 



xxvn.) 



43. SESLERLA.. — Florets with a short awn from the summit; 

 longer than the calyx. Glumes of about equal lengths. Inflorescence 

 close, compact, of an oval form. One species, (Plate XVIL i 



Exceptions. Some species of the genus Poa (of the next division) have but two flo- 

 rets in each calyx, which are readily distinguished by the outer palea having no awn, 

 with the lower half of the keel hairy. RottbolUa of the preceding division has occasion- 

 ally two florets in each calvx. 



