158 



CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



LaxifLora. — Plants light green, vernal culms 10 to 40 cm. high, numerous in tufts; 

 blades flat, soft, mostly ciliate, basal blades shorter, but not forming true 

 rosettes in the autumn; ligules nearly obsolete, primary panicles long-exserted ; 

 spikelets 1.3 to 2.3 mm. long, obovate, obtuse, turgid, 5 to 7-nerved. 

 Autumnal form freely branching near the base, forming close, flat, soft tufts, 

 the reduced panicles often exceeded by the leaves. 

 Sheaths retrorsely pilose; spikelets papillose-pilose. 



Panicle branches ascending, forming a rather compact 



panicle; spikelets 1.6 mm. long 87a. P. xalapense stric- 



tirameum. 

 Panicle branches loosely spreading. 



Blades ciliate and more or less pilose on the surface; 



spikelets 2 mm. long 87. P. xalapense. 



Blades glabrous or nearly so on the surface and mar- 

 gin; spikelets 2.2 mm. long 86. P. laxifiorum. 



Sheaths not retrorsely pilose; spikelets pubescent or glabrous. 



Spikelets pubescent, about 2 mm. long 88. P. ciliatum. 



Spikelets glabrous. 



Blades glabrous on the surface 89. P. polycaulon. 



Blades pilose on the surface 90. P. strigosum. 



86. Panicum laxifiorum Lam. 



Panicum laxifiorum Lam. Encycl. 4: 748. 1798. "Cetteplante est dans l'herbier du 

 Museum. Je la crois d'Amerique Septentrionale." The type, labeled in Lamarck's 

 hand "panicum laxifiorum lam. diet.," is in the Lamarck Herbarium. It consists of 

 two culms, each with a loose terminal panicle, one leafless, the other with a single 

 blade glabrous on both surfaces; the spikelets are 2.2 mm. long, papillose-pilose, the 

 fruit covered by the second glume and sterile lemma. These characters indicate not 

 the species that has been called by this name in America, but the one of more restricted 

 southern range. 



Panicum pyriforme Nash, Bull. Torrey Club 26: 579. 1899. "Type collected by the 

 writer in clay soil, at Orange Bend,« Lake Co., Florida, March 12-31, 1894, no. 239." 

 The type, in Nash's herbarium, consists of a clump of three culms, 15 to 45 cm. high. 



The description states that the blades are glabrous 

 on the margin, but the type, as well as duplicate 

 types in the National and Columbia University 

 herbaria and in Hitchcock's herbarium, has sev- 

 eral sparingly ciliate blades; the spikelets are said 

 to be "about 2.5 mm. long" but measure 2.2 mm. 

 Panicum aureum Muhl.; Scribn. & Merr. U. S. 

 Dept. Agr. Div. Agrost. Circ. 27: 4. 1900. This 

 is mentioned as a synonym of P. laxifiorum Lam. 

 The type specimen is in the Muhlenberg Herba- 

 rium in folio "187, Panicum strigosum." It is labeled "117 P. aureum M 115." 



FlG. 144.— P. laxifiorum. From 

 type specimen. 



DESCRIPTION. 



Vernal form with slender culms 20 to 60 cm. high, erect, or the lower nodes often 

 geniculate, glabrous; nodes bearded with reflexed hairs; sheaths shorter than the 

 internodes, conspicuously retrorsely "pilose; blades mostly 10 to 18 cm. long, 7 to 12 

 mm. wide, acuminate, narrowed toward the base, glabrous on both surfaces and on 



a The locality of Nash 239 as given on the label is "vicinity of Eustis." Orange 

 Bend is a few miles northwest of Eustis. 



