D2. 
4, First glume about 1/2 as long as the spikelet, 
acute or acuminate; sheaths hirsute or 
villous; nodes bearded. (Also, panicle 
erect; spikelets not more than 4 mm. long). 
5. Panicle more than 1/2 the entire length 
of plant. (Also, panicle as broad as 
lons)rm\ spikelets 2=2 55! mm. Pome. seseheye! oe sereers P. capillare 
5. Panicle not more than 1/3 the entire 
length of plant. Expected (P. philadelphicum). 
2. Plants perennial. 
6. Plants without creeping, scaly rhizomes. 
Expected (P, agrostoides, P. stipitatum). 
6. Plants with creeping, scaly rhizomes. 
7. Pedicels of spikelets usually over 3 mm. long. 
8. Panicle long and narrow; spikelets 5-6.5 
mm. long; sandy seacoast habitat. Expected 
(P. amarum). 
8. Panicle moderately diffuse; spikelets 
4.5 mm. long; salt marsh and tidal stream 
habitat. (Also, culms rigid, terete; 
sheaths not compressed)...... #181 vous, e010 « ... P. virgatum 
7. Pedicels of spikelets 1-3 mm. long. (Also, 
panicle open; spikelets 3.3-3.7 mm. long; 
culms firm to soft; culms and sheaths 
compressed; terrestrial habitat)..........s.0. P. anceps 
. Basal leaves unlike the cauline ones, forming winter 
rosettes (except in P. depauperatum, the leaves then 
crowded near the base). 
9. Spikelets glabrous or nearly so. 
10. Spikelets about 3.5 mm. long. (Also, sheaths 
pilose; blades scabrous above, pilose beneath). 
Expected (P. depauperatum). 
10. Spikelets less than 3 mm. long. 
11. Spikelets 1.5 mm. long or less. (Also, ligule 
not over 1.5 mm. long; nodes bearded)...... P. microcarpon 
11. Spikelets 2-3 mm. long. Expected (5 species, 
especially P. dichotomum). (Also, blades 2 
cm. wide or more, strongly nerved, scabrous, 
round at base; spikelets 3 mm. long). 
