HITCHCOCK AND CHASE NORTH AMERICAN PANICUM. 



281 



sheaths loose, shorter than the internodes, usually less copiously pilose than the culm; 

 ligules 1 to 1.5 mm. long; blades spreading or ascending, 7 to 10 cm. long, 6 to 12 mm. 

 wide, tapering to the rounded base, acuminate, rather thin, velvety on both surfaces, 

 ciliate at least toward the base; panicles usually short-exserted, 3 to 7 cm. long, at 

 first narrow, the lower branches finally spreading, with short, spikelet-bearing branch- 

 lets in the axils; spikelets 2.9 to 3 mm. long, 1.5 to 1.7 mm. wide, elliptic-obovate, 

 obscurely pointed, turgid at maturity, papillose-pilose; first glume about one-third 

 as long as the spikelet; second glume and sterile lemma equaling the fruit at maturity; 

 fruit 2.2 mm. long, 1.5 mm. wide, elliptic. 



Autumnal form spreading, freely branching from the middle and upper nodes before 

 the maturity of the primary panicle, 

 at length forming bushy, topheavy 

 clumps with reduced blades and 

 numerous secondary panicles. 



DISTRIBUTION. 



Sandy woods, Tennessee and Mis- 

 souri to Oklahoma and Texas. 



Missouri: Warrenburg, Stigall 8. 

 Tennessee: Nashville, Gattinger 



in 1880; Lavergne, Gattinger 



in 1881 and 1882. 

 Arkansas: Mountain Park, Coville in 1887; Prescott, Bush 263. 

 Texas: Dallas, Bush 642, Reverchon 1831; Weatherford, Tracy 7942; Denison, 



Bebb 2670 (Hitchcock Herb.). 

 Oklahoma: On the False Washita, Palmer 383 in 1868; Wister, Hitchcock 578. 



Fig. 316. — Distribution of P. rnalacophyllum. 



170. Panicum helleri Nash. 



Ponicum helleri Nash, Bull. Torrey Club 26 : 572. 1899. "Collected at Kerrville, 

 Kerr Co., Texas, by A. A. Heller, May 14-21, 1894, No. 1759. Differs from P. perner- 

 vosum in the pubescent culm and sheaths, the broader blades of a different shape and 

 the narrow spikelets which are usually sparsely pubescent." The type, in Nash's 

 herbarium, is a tuft of five vernal culms 24 to 39 cm. high, the lower nodes subgeni- 

 culate; panicles immature, scarcely exserted, the upper spikelets well developed 

 but not mature, 3 mm. long, 1.5 mm. wide, bearing a few scattered hairs; papillae on 

 the sheaths not prominent; lower internodes sparsely ascending-pilose, the upper 

 short-pubescent, as frequently found in P. scribnerianum. The blades are 6 to 12 mm. 

 wide, while those of the type of P. pernervosum are 5 to 7 mm. wide, but both are of 

 the same shape, broadest in the middle instead of near the base, as in P. scribnerianum. 



Panicum pernervosum Nash, Bull. Torrey Club 26 : 576. 1899. "Type collected by 

 Elihu Hall in woods at Houston, Texas, April 16, 1872, No. 830." The type, in the 

 herbarium of the New York' Botanical Garden, consists of two vernal plants with 

 culms 27 and 34 cm. high, and an extra piece of culm with a panicle. The culms are 

 glabrous, the sheaths ciliate on the margin, otherwise glabrous, except one which has 

 a few hairs near the summit. The panicles are mature and the spikelets more turgid 

 than in the type of P. helleri, being 3 mm. long and 1.7 mm. wide. A few of them 

 bear a few scattered hairs. 



DESCRIPTION. 



. Vernal form in clumps of few to several culms, usually somewhat bluish light green; 

 culms 25 to 60 cm. high, slender, ascending or spreading, the lower internodes 

 appressed-pilose, the upper often glabrous ; sheaths sparsely papillose-hispid to glabrous, 

 the papillae often without hairs as in P. scribnerianum, ciliate on the margin; ligules 



