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ATRA ALPINA. 
Linnevs. Hooker anp Arnott. Parnett. Basineton. LInpDLey. 
WILLpDENOoW. WaAHLENBERG. 
PLATE XXI.—A. 
Aira levigata, J. E. SMITH. 
The Smooth Alpine Hair-Grass. 
Aira—To destroy. Alpina—Mountain. 
AN uncommon and useless Grass, not seen at a less elevation 
than three thousand feet. 
Found on Ben Lomond, Ben Arthur, and moist rocks in 
Angusshire, and said to be found in Wales. 
Native of Lapland, Scotland, and North America. 
Distinguished from Aira fleruosa by the awn rising from 
above the centre of the palea, and not extending beyond the 
apex of the palea. 
Stem upright, circular, and polished, carrying three or four 
narrow, acute, mostly involute, strongly-ribbed leaves, rough on 
inner surface and margins, smooth on back, with smooth striated 
sheaths. Joints smooth. Inflorescence compound panicled. Pani- 
cle upright, silky, brown. Apex drooping. Branches arranged 
on the smooth rachis in pairs at certain distances. Spikelets 
numerous, with exceedingly delicate footstalks, usually two, 
though occasionally three, awned florets, the lower one not 
protruding beyond the calyx. Calyx of two nearly equal mem- 
branous smooth glumes. Upper glume three-ribbed, others 
destitute of lateral ribs. Florets of two pale, exterior one of 
lowest floret shorter than the glumes; oval in shape; base hirsute; 
N 
