24 



506 THE GRASS FAMILY. 



( Awns to all the glumes 12. POLYPOGOH. 



21 ( Awns (often very small) to the flowering glume only, or none. Outer glumes 



( pointed but not awned 22 



Awns jointed, with a tuft of hairs at the joints . . . .17. AlRA. 



Awns not jointed 28 



Outer glumes swollen and very shining at the base . . 14. GASTRIDIUM. 



Outer glumes not enlarged at the base 13. AGROSTIS. 



Spikelets all sessile, in a simple spike (branched only in accidental 



luxuriant specimens) 26 



Spikelets single or clustered, in a loose and spreading or close and spike-like 



panicle 25 



Awns to some or all the glumes 31 



Spikelets entirely without awns 40 



Spikelets 3- or more flowered, sessile in a single spike. 



( Two spikelets to each tooth of the spike 25. ELTMU3. 



26 x Spikelets all solitary 27 



( Spikelets clustered along the axis of the spike 41 



,,/ Spikelets with their sides to the main axis of the spike 28 



' \ Spikelets with one edge (the backs of the glumes) to the main axis . . .29 



( Outer glumes nearly equal. Spikelets very closely sessile, or indented. 

 28 { 27. AOROPYRTTM. 



( Outer glumes unequal. Spikelets almost sessile . . .29. BRACHYPODIUM. 



( One empty glume at the base of each spikelet (except the terminal one). 

 29-^ Spikelets indented in the axis 28. LOLIUM. 



( Two empty glumes at the base of each spikelet. Spikelets almost sessile . 30 

 so / Perennial. Spikelets 6 lines long or more .... FESTUCA elatior. 



\ Annual. Spikelets not above 3 lines long POA loliacea. 



Spikelets 2- or more flowered, panided, awned. 



,/ Flowering glumes all awned 82 



\ Spikelets with 1 awnless perfect flower, and 1 awned male flower . . .88 

 Awns inserted on the back of the flowering glumes, near or below the centre. 

 Hairs on the axis between the flowers short 32 



32 



Awns terminal. Flowering glumes surrounded by hairs longer than them- 



selves 42. ARUNDO. 



Awns terminal or nearly so. Axis of the spikelet without hairs . . .35 



Spikelets 2-flowered 84 



Spikelets 3- or more flowered 18. AVENA. 



Spikelets 2 lines or less. Awn fine, scarcely protruding beyond the glumes. 

 , 17. AlRA, 



Spikelets 3 or 4 lines long. Awn exserted. One of the flowers male only. 



19. ARRHENATHERUM. 

 ( Awns quite or very nearly terminal, sometimes reduced to a very short point 36 

 35 < Membranous edges of the glumes projecting in 2 points beyond the base of the 

 awns .... 30. BROMUS. 



Spikelets crowded in a close spike or dense clusters 37 



Panicle loose or contracted into a long one-sided spike . . 81. FESTUCA. 

 Outer spikelet of each cluster consisting of empty glumes only 33. CYNOSURUS. 



All the spikelets containing flowers 32. DACTYLIS. 



One terminal awnless flower and a lower male flower awned . 3. PANIOUM. 

 Awnless flower the lowest, with a terminal awned male one . . . .39 

 Outer glumes 2 to 3 lines, completely enclosing the flowers and their awns. 



20. HOLCUS. 

 Outer glumes 3 to 5 lines, the flowers or at least their awns protruding. 



19. ARRHENATHERUM. 



Spikelets 2- or more flowered, awnless, panicled or in a compound spike, 



{Spikelets 2 or 3 together to each notch of an apparently simple spike. 

 25. ELYMUS. 

 Spikelets sessile, in close clusters in an apparently simple spike or spike-like 

 panicle 41 

 Spikelets more or less stalked, in a loose or contracted panicle . . . .43 

 ( A small bract at the base of the spikelets or clusters . . 41. SESLERIA. 

 41 \ Outer spikelet of each cluster consisting of empty glumes . . 33. CYNOSURUS. 

 ( Spikelets all containing flowers without bracts at the base of the clusters . 42 



