1901 ] Scribner & Merrill, — New England Panicum 97 
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Panicle diffuse; spikelets 4 to 4.5 mm. long ; - 7. P. VIRGATUM 
Culm leaves erect, linear, often involute  . ‘ j Sees ci 
Culm leaves lanceolate or linear-lanceolate, rolio inati, or clasp- 
ing at the base, generally spreading . : : : , PTT 
Spikelets about 3.5 mm. long, acute or acuminate I3. P. DEPAUPERATUM 
Spikelets 2 to 2.5 mm. long, obtuse : : © 14. P. LINEARIFOLIUM 
Spikelets 3 to 5 mm.long  . i : : : : . i al 
Spikelets 2.5, rarely 3 mm. long, or less . ^ - : : ae 
Panicles strict, narrow, the branches erect; leaves erect 
15. P. XANTHOPHYSUM 
Panicles ovate, open, the branches spreading; leaves spreading or 
ascending . l : : i . : : : : . %19 
Leaf-blades ample, 2 to 3 cm. broad, cordate and clasping at the base 20 
Leaf-blades smaller about 1 cm. broad, not clasping at the base 
IQ. P. SCRIBNERIANUM 
Sheaths papillose-hispid; spikelets 2.5 to 3 mm. long; panicles gener- 
ally much included within the leaf- -sheath, sometimes long-exserted 
16. P. CLANDESTINUM 
Sheaths glabrous or soft pubescent; spikelets 3 to 5 mm. long da 
Nodes strongly bearded; sheaths and leaves generally soft-pubescent, 
sometimes nearly glabrous; spikelets 4 to 5 mm. long 
18. P. LATIFOLIUM 
Nodes naked: sheaths and surface of the leaves glabrous; spikelets 
3to4 mm. long . : A : - 17. P. MACROCARPON 
Whole plant nearly EM TA sometimes bearded; spikelets gla- 
brous or pubescent . : : : : i : À i 20222 
Whole plant more or less pubescent . : i ; : i ic] 
Nodes bearded : . ME. ; : fey | 
Nodes naked or only with a few Louis, jadis i : ae 
Spikelets 1.5 mm. long, glabrous : : . 20. P. BARBULATUM 
Spikelets 2.2. mm. long, pubescent , . 21. P. MATTAMUSKETENSE 
Spikelets glabrous, 2 mm. long . : A . 22. P. DICHOTOMUM 
Spikelets pubescent : : E . : 20 
Leaf-blades cordate-clasping at the base splielbd bu spherical ; 
ligule obsolete . : : . 29. P. SPHAEROCARPON 
Leaf-blades not cordate- DT at the base, spikelets ovate or ellipti- 
cal; ligule present . : è : : : ; : j SUE 
Spikelets 2 mm. long or more . : i : i : : Ln 
Spikelets 1.5 mm. long : t i i 27. P. NITIDUM 
Lower internodes of the culm publerulede: spikelets 2.5-3 mm. long 
(P. bicknellii may be looked for here) . . 24. P. COMMUTATUM 
Lower internodes glabrous : A : " . >. 29 
Leaves spreading, rather rigid ; "T .3 mm. long 28. P. CLUTEI 
Leaves erect, rather soft; spikelets 2 mm. long ; : . ee 30 
Leaves 8-15 mm. wide ; à : i 7 + 25. P. BOREALE 
Leaves 3-6 mm. wide . à . : . . 26. P. WERNERI 
Spikelets 2 mm. long or more . . : . : : ‘ ; $32 
