﻿GRASSES OF SCOTLAND. 8l 



ribbed ; first joint about half-way up the stem ; — whereas in Poa 

 polynoda the florets are perfectly free ; outer palea five-ribbed ; se- 

 cond joint about half-way up the stem, and the first joint near the pa- 

 nicle. (Plate XXXIX.) 



From Poa pratensis, in the upper leaf being about equal in length 

 to its sheath ; stem very much compressed, and contracted under the 

 panicle ; outer palea only three-ribbed ; — whereas in P. pratensis the 

 upper leaf is much shorter than its sheath ; stem very seldom com- 

 pressed ; outer palea five-ribbed. (Plate XXXI.) 



From Poa nemoralis, in the ligule of upper sheath being prominent ; 

 panicle somewhat rigid ; outer palea only three-ribbed ; — whereas 

 in P. nemoralis the ligule is very short, scarcely perceptible ; panicle 

 long and slender ; outer palea five-ribbed. (Plate XXXVI.) 



From Poa ccesia, in the uppermost joint being about the centre of the 

 stem ; florets webbed ; outer palea only three-ribbed ; — whereas in 

 P. cassia the upper joint is situated near the base of the stem ; floi*ets 

 perfectly free ; outer palea five-ribbed. (Plate XL.) 



Were it not for the small quantity of foliage that this grass pro* 

 duces, it would rank as one of the most valuable grasses, as it shoots its 

 leaves early in spring, and possesses a large share of nutritive pro- 

 perties. It grows naturally on dry poor soils, and is found in stony 

 places and wall-tops. 



It is a frequent grass in Scotland, England, and Ireland, also a 

 native of Norway, Sweden, Prussia, Germany, France, Switzerland, 

 Italy, Russia, Greenland, Iceland, and the northern parts of North 

 America. Attains an elevation of 3000 feet above the sea. 



Flowers in the second week of July, and the seed is ripe about the 

 middle of August 



55. Poa alpena.* 



Alpine Meadow^ Grass. 



Specific Characters* — Florets not webbed. Outer palea three- 

 ribbed. Glumes three-ribbed. Upper leaf folded, and shorter 

 than its sheath, Rachis and branches rough, (Plate XXXVII.) 



* Poa (dpirwij Hooker, Smith, Koch, Lind. 

 F 



