26 JOURNAL OF THE 
Spikelets 1°’—1%”’ long, basal secondary panicles devel- 
PIPERS (AGNES eerste abies > ae eT Meets ares 30. P. linearifolium. 
Spikelets barely 1” long, no basal panicles developed 3l. P. 
Werneri. 
Leaves narrowed to the base, lanceolate or narrower, spikelets 14”’ 
—1%” long, plant nearly glabrous, lower nodes barbed 32. P. nemo- 
panthum, 
Stems simple at length fasciculately branched erect, or sometimes 
prostrate, stem leaves numerous, scattered, spreading or ascending, 
lanceolate, 1%”—8” wide, clasping by a rounded or narrowed base, 
the upper generally not conspicuously reduced in size, and never 
elongated, the basal usually shorter than those of the stem; spikelets 
less than 14%” long. 
Nearly or quite glabrous species without a long hairy ligule. 
Nodes not barbed, spikelets 34”—1” long. 
Plant strict, erect. 
Leaves spreading, narrowed to the smooth base 33. 
P. dichotomum. 
Leaves ascending. 
Base of leaves narrowed, rounded, ciliate, sheaths 
TOE IO LECED 7255405, a ons vere 34. P. boreale. 
Leaves narrowed to the glabrous base, sheaths 
et = | ee eer ERR ges os i Te 35. P, maculatum. 
Plant rising from a geniculate base. 
Leaves, oo fone, 54 ee 36. P. Roanokense. 
Leaves less than 1%’ long ......... 37. P. demissum. 
Nodes barbed. 
Spikelets 1) lone <5 or. es ote 38. P. Mattamusketense. 
MiP eelers eae CORE eS Peteet Pols a y's 39. P. barbulatum, 
Nodes not barbed, spikelets less than 34” long. 
Strict, not prostrate or reclining ; 8’—16’ high. 
Leaves 1”°—3” wide, with a firm, white margin 40. P. 
ensifolium., 
Leaves 1” wide or less, densely tufted. 
Branched only from the base ... 41. P. Baldwinii. 
Much branched towards top of culm...... 42. P. 
Wrightianum. 
Stems at first erect, at length elongated and reclining, 
spikelets obovate, 4” long ........ 43. P. sphagnicolum, 
Stems prostrate, spikelets broadly elliptical 34” long 44. 
P. lucidum. 
Stems ascending or reclining, spikelets narrowly ellipti- 
cal, 33h" Senge 0.1 anne. vere mee 45. P. Cuthbertii. 
Nearly or quite glabrous species with a long pilose ligule. 
Spikelets 2”’ long or less. 
Spikelets about '%” long ‘i. 6.61 7.26. 46. P. parvispiculatum, 
