A<jroslis. CJllAMINEiK. 271 



witli the rudiment of a second. (Jliiincs somewhat unequal, tlie lower rather longer, 

 obtuse or acute, but pointless or awnless (except in n. 11), membranaceous. Floret 

 mostly shorter than the glumes, with a very short naked or liairy callus. Palets 

 one or two, very thin, the lower 3-5-nerved, pointless, naked, often bearing a slen- 

 der straight awn on the back usually much below the apex ; upper palet obsolete, or 

 present and shorter than or equalling the ovary, rarely nearly as long as the lower 

 palet. Scales 2, entire. Stamens mostly 3. Styles 2 ; stignias feathery. Grain 

 free, terete, smooth. 



A rather lar;,'e genus, widely distrihuted in cold and temj)erate climates ; the number of species 

 is estimated at about 60, though over 200 are recorded. In iiigh latitudes the species vary 

 greatly, especially as to the awn, tlie jHcsence or absence of which has little value as a character. 

 They are mostly perennials, with slender low culms which form dense tufts. A few are useful as 

 pasture grasses, but on account of the general sparseness of their foliage are not much valued for 

 mowing. 



* Spikelcts with the rudiment of a second floret. — rouAono.STis, Griscb. 



1. A. eequivalvis, Trin. Culm 1 to 2 feet high, erect, slender, smooth : leaves 

 Hat, 4 to G inches long, the uppermost very short, and about a line wide, smooth or 

 nearly so, very pale green ; upper ligules about a line long ; sheaths smooth, shorter 

 than the internodes : panicle 2 to 6 inches long, loose, ver}' narrow, smooth and 

 shining, the distant rays in whorls of 5 below, in pairs or solitary above, very un- 

 equal, the longer U to 2 inches long, nearly smooth and mostly ilower-bearing above 

 the middle: spikelets from 1 to 1^ lines long, mostly in pairs, one with a pedi- 

 cel shorter and the other with one longer than itself, sometimes pur})lish : glumes 

 nearly equal, acute, the u|)per 3-nerved : lloret equalling the glumes, with a minutely 

 hairy callus, and a small hairy rudiment \ or \ its length : lower palet acute, 

 5-nerved ; upper palet about as long as the lower. — Agrost. ii. 116. A. canina, 

 var. (vquivalvis, Trin. in liong. Veg. Sitch. 171. A. Hillebrandii, Thurber; Boland. 

 in Trans. Calif. Agric. Soc. 1864, 136. 



Calaveras County {Dr. HUlchrand); Mariposa Crove (Bolandcr) ; Oregon, ILiU. Also Sitka 

 and Unalaschka. A perennial accoiiling to Trinius, but all our specimens l;u-k the root and the 

 weak culm has much the apjiearance of an annual. Trinius describes the rudiment in the far 

 northern specimens as two-thirds the length of the floret, but it does not reach that in those col- 

 lected in California and Oregon. In the Oregon i)lant the panicle is shorter and the flowers pur- 

 plish, while the Calaveras County specimens are noticeable for the unusually pale green of both 

 jianide and fcdiiige. 



* * Spikelets st.rictlij 1-flowered, without the rudiment of a second floret. 



•»- Uj)2)er imlet present, one third (or more) the lenflh of the lower. — Agrostis 



proper. 



++ Panicle elongated. 



2. A. alba, Linn. Culms varying from a few inches to 2 feet high, sometimes 

 decumbent at base : leaves flat, short, smooth or roughened ; sheaths smooth ; ligule 

 short and truncate or long and acute : panicle slender, usually spreading when in 

 flower and more or less contracted afterwards, green, purplish or brownish, rays 

 roughish : spikelets one line long or less : glumes nearly eipial, the lower slightly 

 longer : floret slightly shorter than the glumes, the brief callus with some very minute 

 hairs ; lower palet very thin, 5- or 3-nerved, rarely with a short awn ; iq>per palet 

 ^ to I the length of lower. — A. slolnnifern, Linn. ; Keichoid). Icon. V\. Germ. i. 9, 

 t. 133-137, 139. A. vid<jaris, With.'; lleichenb. 1. c, t. 130-132. 



A native of Euroj)e, introduced in most of the cultivated portions of the State and of the 

 country, and exceedingly variable, its didercnt forms having given ground for over 30 nomi- 

 nal species. In most woiks A. nlba and A. viihjnris are kept distinct, perhaps from the fact that 

 they are recognized as dillcrent in agriculture, the oidy botanical ciiaracter that can separate them 

 being the didereiice in theleiigth of the ligule. They may be distinguished as follows : — vnr. alba 



