HITCHCOCK AND CHASE NORTH AMERICAN PANICUM. 249 



and base, the long hairs sometimes mixed with appressed pubescence beneath ; panicles 

 1.5 to 4 cm. long, about as wide; spikelets 1.3 to 1.4 mm. long, rounded obovate, very 

 turgid, pubescent; second glume shorter than the fruit at maturity ; fruit 1.1 mm. long, 

 0.8 mm. wide, obtuse. 



Autumnal form widely spreading, the branches appearing earlier than in the species, 

 shorter and usually more crowded and somewhat aggregated toward the summit. 



A few specimens intermediate between the species and subspecies occur, as Kearney 

 10, District of Columbia, which has the habit and pubescence of the subspecies but 

 spikelets 1.5 mm. long; Chase 3559, Atsion, New Jersey, and Commons 58, Rehoboth, 

 Delaware, which have the stouter culms and crisped pubescence of the species but 

 spikelets 1.4 mm. long. Short speci- 

 mens with much crowded branches 

 resemble P. oricola, from which they 

 may be distinguished by the smaller 

 spikelets and less dense pubescence. 



DISTRIBUTION. 



Dry sands, Massachusetts to Virginia. 

 Massachusetts : Nantucket, Bich- 



nell in 1899 and 1904. 

 New Jersey: Mantoloking, Lyon 



in 1902; Atsion, Chase 3534, 



3560, Saunders & Clute 2 ; Toms 



River, Chase 3577; Forked River, Chase 3588; Tuckerton, Chase 3605. 

 Maryland: Hyattsville, Chase 3806. 

 Virginia: Lynn Haven, Hitchcock 406 . 



Fig. 270.— Distribution of P. columbianum thinium. 



148. Panicum oricola Hitchc. & Chase. 



Panicum oricola Hitchc. & Chase, Rhodora 8: 208. 1906. "Type Hitchcock 47 in 

 National Herbarium. Prostrate clumps on bare sand on low mounds between marsh 

 and sand dune. Lewes, Del., June 18, 1905, collected by A. S. Hitchcock." This 

 specimen is the early autumnal form. 



DESCRIPTION. 



Vernal form grayish, often purplish; culms densely tufted, 10 to 30 cm. high, 

 spreading, densely appressed or ascending pilose, the hairs on the nodes spreading; 

 sheaths usually more than half the length of the internodes, appressed-pilose ; ligules 



1 to 1.5 mm. long; blades firm, erect or ascending, 2 

 to 5 cm. long, 2 to 4 mm. wide, broadest near the base, 

 acuminate, the upper surface pilose with hairs 3 to 5 

 mm. long, the lower surface appressed-pubescent with 

 longer hairs intermixed; panicles short-exserted, or 

 rarely long-exserted early in the season, 1.8 to 3 cm. 

 long, rarely longer, about two-thirds as wide, rather 

 densely flowered, the axis appressed-pubescent, the 

 flexuous branches ascending or spreading; spikelets 

 1.5 mm. long, 1 mm. wide, broadly obovate, turgid, obtuse, pubescent with short 

 spreading hairs; first glume one-third to half the length of the spikelet, abruptly 

 pointed; second glume and sterile lemma barely equaling the fruit at maturity; fruit 

 1.3 mm. long, 0.9 mm. wide, broadly elliptic, very turgid. 



Fig. 271 



From type 



