100 TRIANDRIA— DIGYNIA. Aira. 



P. sylvestre herbariorum. Park. Thealr. 1154./. 



P. vulgare. Gar. Em. 85./. 



Gramen paniceum, spicu divisa. Bank. Pin. 8. Theatr. \36.f. 

 Scheuchz. Ai^r. 49. Rali Sun. 394. Moris, v. 3. 189. w. 15. sect.S. 

 t.4.f.\5; ^alson. lO.f. 16. 



In moist arable land, but rare. 



Near Guildford. Huds. About Battersea, Putney, and Greenwich. 

 Rcnjj Lightfoot, Curtis, &c. 



Annual. July. 



Root fibrous. Stems several, often 2 feet high, stout, leafy, smooth, 

 with some tufts of radical leaves, and a few short, more spread- 

 ing, stems, at their base. Leaves harsh, pointed^ neither warty 

 nor hairy. There are no stipulas of any kind, one represented in 

 Engl. Bot. being an error. Sheaths compressed, striated, smooth. 

 Panicle erect, rigid, unilateral, with angular rough-edged stalks 5 

 its lower branches rather distant, and zigzag j upper crowded 5 

 all with tufts of fine smooth bristles, originating in tubercles, at 

 their base ; which bristles seem not essentially different from 

 those of Richard's Pennisetum, and greatly invalidate the sup- 

 posed character of that genus, of which our two foregoing species 

 are examples. The larger valve of the calyx is ovate, concave, 

 ribbed, bristly, pointed, or slightly awned^ smaller cup-shaped, 

 embracing the whole base of the flower. Cor. of the perfect 

 floret 2 ovate awnless valves, very smooth, and even, finally 

 horny, coating the seed 3 the larger concave, obscurely ribbed ; 

 the inner smaller, flattish : that of the neuter floret of 2 very 

 dissimilar valves ; the outermost resembling the outer valve of 

 the calyx, to which it has heretofore been supposed to belong, 

 concave, ribbed, bristly, inflexed at the edges, and terminating 

 in a rough, straight awn, generally short, as in Engl. Bot., but 

 sometimes very long as in Leers, and Morison's/. 16 ; the in- 

 nermost rather smaller, thinner, flat, notched at the tip, see 

 Curtis,/. 5. Stam. and Pist. in the perfect fl. only, about as 

 long as the corolla, and formed like those of the 2 species above 

 described. 



The Linnoean P. Crus-corvi proves not a distinct species from this. 



39. AIRA. Hair-grass. 



Lin7i. Gen. 34. Juss.3\. FL Br. 83. Lam. t. 44. Gcrrfn. t.\. 



Cal. of 2 unequal keeled valves, containing a spikelet of 2 

 perfect ^or^/5, one of them generally elevated on a short 

 stalk, without any rudiments of a third. Cor. of 2 oblong, 

 unequal, clasping valves; the outer one largest, with a 

 dorsal tw^isting awn, above the base, in several species 

 wanting; inner notched at the point, awnless. Nect, a 

 cloven scale. Filcmi. capillary. Anth, prominent, pen- 

 dulous, notched at each end. * Germ, ovate. Stijles short, 



