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, MacouninlSGB, seem to be intermediate between this species and P. leibergii. 

 The first of these has the glabrous blades and strict panicles of P. xanthophysum, 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 P. 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. xanthophysum unhesitatingly but for the intermediate vernal 

 specimen. 



DISTRIBUTION. 



Fig. 327.— p. xanthophysum. From type specimen. 



Sandy or gravelly soil, Quebec to Minnesota, south to Pennsylvania. 

 ' Quebec: Sorel, Prmg-Ze 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 Hampshire: Laconia, Carter 1016.. 

 Vermont: Burlington, Jones in 1893; Peacham, Blanchard in 1889; Vernon, 



Grout in 1895. 

 Massachusetts: Ashburnham, Harris in 1896 (N. E. Bot. Club Herb.). 

 Connecticut: Stafford, Graves in 1903 (Gray Herb.). 



