﻿GRASSES OF SCOTLAND. 5 



* * * Calyx containing two Florets. * 

 27. MELICA. — Florets without awns, not longer than the calyx. 

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



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

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



31. MOLINIA. — Florets without awns, much longer than the calyx. 

 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 XXII.) 



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

 about equal lengths. Five species. (Plates XXIII. XXIV. XXV.) 



40. ARRHENATHERUM.— 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. XXVI.) 



41. A VENA. — Florets awned from a little beneath the centre. 

 Glumes not less than seven ribbed. Two species. (Plates XXVI. 

 XXVII.) 



43. SESLERIA. — 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 XVII.) 



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. Rottbollia of the preceding division has occasion- 

 ally two florets in each calyx. 



