82 



GRASSES OF SCOTLAND. 



Description.— It grows from four inches to a foot in lieight. The root 

 is perennial, fibrous, tufted. Stem round, smooth, erect, bearing two or 

 three leaves with smooth striated sheaths ; the upper sheath much 

 longer than its leaf, crowned with a long pointed membranous li- 

 gule. (Fig 5.) Second sheath seldom extending as high as the first 

 jomt. Joi)its two, smooth. Leaves short, mostly flat, rough on the 

 edges and inner surface, smooth and polished behind ; upper leaf 

 folded, compressed, rounded behind the summit. Inflorescence pani- 

 cled. Panicle rather close, erect ; branches rough, the lower ones 

 generally in pairs. Spikelets broadly ovate, erect, very frequently vi- 

 viparous, (Fig. 4), (that is, the inner palea transformed into small 

 leaves,) usually of four awnless florets ; the summit of the lower flo- 

 ret projecting beyond the calyx. Calyx of two broad, acute, equal 

 glumes, (Fig. 1), thvee-ribbed, and minutely toothed on the keels. 

 Florets not ivebbed ; of two paleae, (Fig 2); the outer palea of lower- 

 most three ribbed, (Fig. 3); the lower-half of the dorsal and lateral 

 ribs furnished with silky hairs. Inner palea rather shorter than the 

 outer palea, membranous, with two green marginal ribs minutely 

 fringed. 



Obs. — Poa alpina somewhat resembles Poa laxa, but the panicle 

 is more compact, erect ; the lower branches much shorter ; the root 

 much tufted; upper leaf folded, compressed, and rounded behind 

 the point; spikelets broadly ovate, approaching to cordate, and the 

 radical leaves shorter and more obtuse : — whereas in P. laxa the pa- 

 nicle is slender and slightly drooping ; the loioer branches long ; the 

 root not tufted ; upper Zf of flat, lanceolate, and taper- pointed ; spike- 

 lets oblong ovate, and the radical leaves linear, lanceolate. (See 

 Plate XXXVIII.) 



From Poa ccssia, in the upper sheath being much longer than its 

 leaf ; liyule long and pointed ; and the outer palea three-ribbed ; — 

 whereas in P. ccesia the upper sheath is about equal in length to its 

 leaf ; ligule obtuse ; and the outer palea five-ribbed. (See Plate XL.) 



From Poa pratensis, in the florets not being webbed, and the li- 

 gule long and pointed ; — whereas in P. pratensis the two lowermost 

 florets are furnished at the base with a copious web suspending the 

 calyx; and the ligule is rather short and obtuse. (See Plate XXXI.) 



Although Poa alpina is naturally confined to the alpine regions 



