59 



16. Callus and prolongation of the rachilla naked; empty glumes 



unequal; flowering glume awned from the apex. 63. Apera 



17. Empty glumes smooth or minutely scabrous along the keel. 



58. Agrostis 



17. Empty glumes more or less hairy and of about the same length 



as the flowering glumes 18 



18. Empty glumes connate at the base; palea none; inflorescence 



a dense, cylindrical or oblong, spike-like panicle. 



48. Alopecurus 



18. Empty glumes distinct ; palea present; inflorescence capitate, 



very woolly 64. Lagurus 



19. Flowering glumes flattened on the back, strongly indurated 



and shining 42. Milium 



19. Flowering glumes not flattened on the back nor strongly in- 



durated 20 



20. Eachilla prolonged behind the palea (the 1 -flowered species 



of Melica may be looked for here) 21 



20. Eachilla not prolonged 22 



21. Empty glumes longer than the flowering glume; callus and 



prolongation of the rachilla hairy; panicle densely flowered, 

 elongated, and spike-like 61. Ammophila 



21. Empty glumes, or at least one of them, shorter than the flow- 



ering glume; callus and rachilla naked . . 56. Arctagrostis 



22. Nerves of the flowering glume densely silky-villous nearly to 



the apex 52. Blepharoneuron 



22. Nerves not densely silky-villous 23 



23. Pericarp free or separable from the grain, sometimes opening 



at maturity ; first empty glume usually shorter than the sec- 

 ond and exceded by the flowering glume . 51. Sporobolus 



23. Pericarp closely adherent to the grain 24 



24. Flowering glumes hyaline, shorter and much more delicate in 



texture than the empty ones 25 



24. Flowering glumes membranaceous, herbaceous, or chartaceous, 



not more delicate in texture than the empty ones 26 



25. Empty glumes abruptly awn-pointed, the keels strongly ciliate. 



47. Phleum 



25. Empty glumes not abruptly awn-pointed, keels smooth or 



simply scabrous 58. Agrostis 



26. Empty glumes minute, sometimes only one; stamen one. An 



arctic grass 50. Phippsia 



26. Empty glumes conspicuous; stamens three 27 



