506 THE GRASS FAMILY. 



( Awns to all the glumes 12. Polypogon. 



21 1 Awns (often very small) to the flowering glume only, or none. Outer glumes 



( pointed but not awned 22 



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



X Awns not jointed 23 



23 / Outer glumes swollen and very shining at the base . . 14. Gastridium. 



\ Outer glumes not enlarged at the base 13. Agrostis. 



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

 24 J luxuriant specimens) 26 



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



X. panicle 25 



„k /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. Elymus. 



26 < Spikelets all solitary . .27 



( Spikelets clustered along the axis of the spike 41 



2Y / Spikelets with their sides to the main axis of the spike 23 



X 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 -j 27. AGROPYRUM. 

 ( 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 



„ / Perennial. Spikelets 6 lines long or more .... Festuca elatior. 

 X Annual. Spikelets not above 3 lines long TOAloliacea. 



Spikelets 2- or more flowered, panicted, awned. 



o-, f Flowering glumes all awned 32 



X Spikelets with 1 awnless perfect flower, and 1 awned male flower . . .38 



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

 Hairs on the axis between the flowers short 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 



qo /Spikelets 2-flowered 34 



^(Spikelets 3- or more flowered 18. Avena. 



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

 oj 17. AlRA. 



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

 t 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. 



qfi ( Spikelets crowded in a close spike or dense clusters 37 



\ Panicle loose or contracted into a long one-sided spike . . 31. Festuca. 

 oy ( Outer spikelet of each cluster consisting of empty glumes only 33. Cynosurus. 



' t All the spikelets containing flowers 32. DACTYLIS. 



„ 8 /One terminal awnless flower and a lower male flower awned . 3. PANICUM. 

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



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

 oq! 20. HOLCUS. 



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

 V. 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. 

 Outer spikelet of each cluster consisting of empty glumes . . 33. Cynosurus. 

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



