52 t.RAMINEAE. 



Awn of the bractlet arising from below the teeth of the apex, not from between them. 



Lower flower always perfect; the uppermost sometimes staminate or reduced to its 



bractlet. 



Spikelets less than 5 lines long (excluding the awn); achene free from the bractlet 



and palea, unfurrowed. 



Bractlet finely erose-dentate, or 2dobed, or truncate and entire; spikelets strictly 



2, rarely 1-flowered 18. Df.schampsia. 



Bractlet cleft or 2-toothed, with the teeth sometimes produced into awns; lowest 



flower awned; spikelets 2 to 6-flowered, often shining 19. Trisetum. 



Spikelets more than 5 lines long (excluding the awn) ; achene usually adnate to 



its bractlet and palea, furrowed 20. Avena. 



Lower flower staminate, strongly awned from near the base; the upper perfect, 



awnless or short-awned at the apex 21. Arrhenatherum. 



Awn of the bractlet arising from between its lobes or teeth; the teeth in many cases 

 prolonged into straight awns 22. Danthonia. 



16. HOLCUS L. Velvet-grass. 



Leaf-blades flat. Spikelets much compressed laterally, 2-flowered ; pedicels 

 jointed below the bracts, so that these are readily deciduous with the flower. 

 Bracts 2, boat-shaped, keeled; lower 1-nerved; upper larger, 3-nerved, notched, 

 acute or sometimes shortly awned. Eachilla shortly prolonged beyond the inser- 

 tion of the uppermost flower-enclosing bractlet, sometimes terminated by a 

 minute rudimentary bractlet. Lower flower perfect; upper staminate. Bracelets 

 shorter than the bracts, 3-nerved; that of the lower flower awnless, of the 

 upper with a short dorsal somewhat twisted awn. Palea 2-nerved, truncate, 

 3-toothed. Scales oblique, acuminate. Stamens 3. Ovary glabrous; stigmas 

 sessile. (Holkos, a Greek name for some grass, perhaps derived from holkos, 

 attractive.) 



1. H. lanatusL. Mesquit-grass. Perennial; rootstock creeping, fibrous; 

 stems tufted, ascending, 1 to 2 ft. high, slender, leafy; sheaths densely soft- 

 pubescent, the uppermost inflated; ligule short; blades soft; panicle pyramidal 

 2 to 5 in. long, pale green or pinkish; branches 2 to 3-nate; spikelets about 2 

 lines long, elliptic-oblong, the awn erect and often exserted before authesis, 

 then incurved and scarcely or not at all protruded; bracts acute, ciliate on the 

 keels, nerves prominent; anthers rich purplish-brown. 



A conspicuous softly-woolly pale-colored grass of moist bottom lands. 

 Naturalized from Europe. San Francisco; Cobb Mt. ; Olema; Pt. Reyes; Guer- 

 neville. 



17. AIRA L. Hair-grass. 



Slender, dwarf annuals. Leaf-blades setaceous. Panicle-branches capillary, 

 sub-erect. Spikelets less than 2 lines long, in ours strictly 2-flowered; bracts 

 thinly scarious; rachilla not prolonged beyond the insertion of the upper 

 bractlet. Bractlets thin, scarious, not projecting beyond the bracts; awn dorsal, 

 short, hair-like. Near to Avena in technical characters, but spikelets much 

 smaller. — (Greek aim, the name of a weed in wheat-fields, probably Lolium 

 temulentum ; from airein, to hurt, on account of its poisonous qualities.) 



Panicle branches much divided and bearing tufts <d spikelets al the ends; bractlet of 



h Sower awned 1. . /. caryophyllea. 



Panicle more open; spikelets less numerous and nol tufted, smaller; bractlet of the lower 

 flower awnless, of the upper awned 2. A. capillaris. 



1. A. caryophyllea L. Silver! Hair-grass. Slender, graceful, tufted 

 . 8 i" 13 in. high; sheaths scabrid, often pinkish a1 the base; blades short. 

 fine, ephemeral; panicle Loose; branches long, much divided, and bearing 

 usually dense tufts of spikelets ;it the ends; pedicels 1 to 2% lines long, 

 scabrid; Bpikelets l'i lines long; bracts widely gaping al the apex, shining 

 above, thinly scarious, the flowers plainly discernible through them; bractlet 



