HITCHCOCK AND CHASE—NORTH AMERICAN PANICUM. 291 
DESCRIPTION. 
Vernal form yellowish green, in loose tufts of few to many culms, 20 to 55 cm. high, 
erect or ascending, more or less scabrous; sheaths loose, about as long as the internodes 
or longer, sparsely papillose-pilose and ciliate at least toward the summit, rarely nearly 
glabrous; ligules 1 mm. long; blades erect or nearly so, rather thin, prominently nerved, 
10 to 15 cm. long, rarely longer, 1 to 2 cm. wide, acuminate, slightly narrowed to the 
rounded papillose-ciliate base, otherwise glabrous, the uppermost blade not reduced, 
sometimes the largest; panicles finally long-exserted, 5 to 12 cm. long, very narrow, 
sometimes appearing almost racemose, few-flowered, the stiff branches erect or nearly 
so; spikelets 3.7 to 4 mm. 
long, 2 to 2.1 mm. wide, 
obovate, turgid and blunt at 
maturity, pubescent; first 
glume about half as long as 
the spikelet, pointed; sec- 
ond glume scarcely equal- 
ing the fruit and_ sterile 
lemma at maturity; fruit 
2.9 to 3 mm. long, 2 mm. 
wide, obovate-oval, mi- 
nutely umbonate. 
Autumnal form erect or 
ascending, branching from 
the second and third nodes, 
the branches erect, mostly simple, the blades not reduced, usually equaling the short- 
exserted panicles, the large, erect blades making the plant appear leafy in the middle. 
The spikelets of the primary panicles sometimes perfect their grains. As stamens 
and stigmas are both frequently exserted, the fruitful spikelets in this species are not 
always cleistogamous as is commonly the case in Dichanthelium. 
Three Minnesota specimens, Campbell 66, Ostland 1 and 2 in 1884, and an Ontario 
specimen, Macoun in 1865, seem to be intermediate between this species and P. leibergii. 
The first of these has the glabrous blades and strict panicles of P. zanthophysum, but 
the blades are only 5 to 7 mm. wide. The Ostland specimens represent vernal and 
autumnal forms; both have blades that are ciliate for half their length or more but 
otherwise glabrous; the panicles are looser as in 7. leibergii and the pubescence of 
the spikelets, which are too immature to indicate amount of turgidity, is papillose- 
spreading as in that species; the autumnal specimen has broader blades and would 
be referred to P. zanthophysum unhesitatingly but for the intermediate vernal 
specimen. 
Fic. 327.—P, zanthophysum. From type specimen. 
DISTRIBUTION, 
Sandy or gravelly soil, Quebec to Minnesota, south to Pennsylvania. 
QuEBEc: Sorel, Pringle in 1879. 
Maine: Buckfield, Allen in 1877; Orono, Fernald 345; Madison, Fernald 521; 
South Berwick, Fernald 519; York, Fernald 520; Bangor, Knight in 1904; 
Cumberland, Knowlton & Chamberlain 500; East Auburn, Merrill 11; Ches- 
terville, Chase 3295, 3300. 
New HampsuireE: Laconia, Carter 101d. 
VeRMONT: Burlington, Jones in 1893; Peacham, Blanchard in 1889; Vernon, 
Grout in 1895. 
MassAcuUSETTS: Ashburnham, //arris in 1896 (N. E. Bot. Club Herb.). 
CONNECTICUT: Stafford, Graves in 1903 (Gray Herb.). 
