84 GEASSES OF SCOTLAND. 



lateral ribs situated near the margins. Inner palea membranous, ra- 

 ther shorter than the outer palea, furnished with two green marginal 

 ribs delicately fringed. 



Jlexuosay a variety most frequently viviparous. The 



branches of the panicle wavy, and the leaves mostly short. (Plate 

 XXXVIII.) 



Ohs. — Poa laxa is distinguished from Poa alpina, in the panicle 

 being more slender and somewhat drooping ; the root not tufted ; 

 upper leaf flat and taper-pointed ; and the spikelets oblong ovate ; — 

 whereas in P. alpina the panicle is compact, erect ; root much tuft- 

 ed ; upper leaf folded, compressed, and rounded behind the point ; 

 and the spikelets broadly ovate. (See Plate XXXVII.) 



From Poa montana, in the upper sheath being much longer than 

 its leaf, and the Ugule long and pointed ; — whereas in P. montana the 

 uj)per sheath is shorter than its leaf, and the Ugule is rather short and 

 obtuse. (See Plate XXXIX.) 



From Poa annua, in the branches of the panicle being rough, and 

 the outer palea three-ribbed ; — whereas in P. annua the branches are 

 smooth and the outer palea five-ribbed. (See Plate XL.) 



From Poa nemoralis, in the upper sheath being much longer than 

 its leaf ; Ugule long and pointed, and the florets not webbed ; — where- 

 as in P. nemoralis the upper sheath is not longer than its leaf; H- 

 gule very short and obtuse, and the lower florets are distinctly webbed, 

 suspending the calyx. (See Plate XXXVI.) 



Poa laxa is a very rare British grass, found on Ben-Nevis, Inver- 

 ness-shire, about 4300 feet above the sea. It is also a native of Lap- 

 land, Germany, Switzerland, Spitzbergen ? and Greenland ? Flowers 

 in the last week of May, and ripens its seed about the end of June. 



57. Poa polynoda.* 

 Silicious Meadow-Grass. 



Specific Characters. — Florets not webbed. Upper sheath not 

 longer than its leaf. Upper joint above the centre of the stem. 



* Poa polynoda, Parnell. This grass is new to the British Flora, and does not appear 

 to have been noticed by continental authors. 



