180 SUMMER FLOWERS. 



(311) Agrostis — panicle loose ; glumes two, nearly equal, the 



upper smaller, acute, without awns ; pales shorter, often 

 bearing an awn below the middle, the inner sometimes 

 wanting ; stamens three ; styles two. 



(312) Apera — panicle loose ; glumes two, acute, the lower small- 



er, nearly equal, without awns ; outer pales with a hair- 

 like awn, 3-4 times as long as the spikelet ; stamens three ; 

 styles two. 



(313) Ammophila — panicle contracted, cylindrical ; glumes two, 



keeled, unequal, awnless, the lower smaller ; pales two, 

 the lower awned under the apex, with hairs at the base ; 

 stamens three ; styles two. 



(314) Calamagrostis — panicle somewhat spreading ; glumes two, 



convex, nearly equal, keeled, pointed ; pales two, unequal, 

 membranous, ribbed, surrounded with hairs at the base, 

 the lower awned ; stamens three : styles two. 



tt ^pikelets two- or few-flowered, pedicellate, the flowering 

 (flumes (pales) usually shorter than the outer ones, their 

 awns often hent or tivisted (Avenese). 



(315) Aira — panicle loose ; spikelets small ; florets equally per- 



fect ; glumes two, nearly equal ; pales two, the lower 

 bifid, with a dorsal straight or slightly-twisted awn ; sta- 

 mens three ; styles two. 

 (31G) Avena — panicle loose; spikelets large; upper florets 

 sterile and imperfect ; glumes two, nearly equal ; pales 

 two, knee-bent, the lower bifid, with a twisted dorsal 

 awn ; stamens three ; styles two. 



(317) Trisetum — panicle oblong, somewhat spreading ; spikelets 



small, crowded ; florets equally perfect ; glumes two ; pales 

 two, the lower deeply cleft, with a twisted, dorsal, knee- 

 bent awn ; stamens three ; styles two. 



(318) Arrlienatlieniin — panicle loose ; upper floret hermaphro- 



dite with a rudimentary prolongation of the axis, lower 

 male ; glumes two, nearly equal ; pales two, the lower 



