112 CONTRIBUTIONS FKOM THE NATIONAL HEKBAEIXJM. 



obsolete; fruit 2.1 mm. long, 0.8 mm. wide, acute, thin in texture, scabrous toward 

 the summit. 



This species seems to be more nearly related to P. polygonatum than to any other, 

 for which reason it is placed, though somewhat doubtfully, in this group. 



DISTRIBUTION. 



Swamps, Mexico. 

 Mexico: Jalapa, Pringle 8195, Schiede & Deppe 674 (Halle Herb.), 



58. Panicum polygonatum Schrad. 



Panicum polygonatum Schrad. in Schult. Mant. 2: 256. 1824. "In Brasilia, ad 

 ripas fluvii Ilheos. Princeps Sereniss. Maxim. Neowidens.'" The type, in the herba- 

 rium of the Botanical Garden in St. Petersburg, has a large pan- 

 icle, pubescent nodes, and a few bristles on the rachis. 



Panicum potamium Trin. Gram. Pan. 239. 1826. "Brasil. 



(Langsdorff)." The type, in the Trinius Herbarium, is from 



near Mandioca, Brazil, collected by Langsdorff "in udis aquosis 



puris." This name is spelled "P. potamicum'" by Steudel.« 



Fig. 107. -p. voiygo- Panicum hydrophilum Trin.; Nees, Agrost. Bras. 208. 1829. 



natum. From type Thig ig giyen ag a g^^ym un d er P. dubium Lam., the specimen 



referred to as ll (Langsdorff. — V. in Herb. Trin.)," doubtless being 



the basis of this name. We have not seen this specimen, but Trinius & refers to this 



name in a note under P. potamium as "olim P. hydrophilum mihi dictam." 



Setaria polygonata Kunth, Rev. Gram. 1: 47. 1829. Based on Panicum polygo- 

 natum Schrad. 



Panicum trichogonum Willd.; Steud. Nom. Bot. ed. 2. 2: 261. 1841. This is given 

 as a synonym under P. polygonatum Schrad. with the following citation: "Willd. 

 hrb. (Sec. Trin. mpt.)." The type, in the Willdenow Herbarium, is labeled 

 "Amer. merid. Humboldt." 



Panicum pilosum polygonatum Doell in Mart. Fl. Bras. 2 2 : 211. 1877. Based on 

 P. polygonatum Schrad. 



Panicum bourgaei Fourn. Mex. PI. 2 : 25. 1886. This name was earlier listed by 

 Hemsley c without description. Fournier cites a single specimen, "In valle Cordo- 

 vensi, januario (Bourgjeau] n. 1662 part.)." The specimen of this number seen at 

 Halle is P. polygonatum, while the one in the Gray Herbarium is P. laxum. The 

 original description calls for a plant with pubescent nodes, which would indicate 

 P. polygonatum. 



description. 



Plants rather freely branching from the lower nodes, widely spreading from a decum- 

 bent or creeping base, rooting at the nodes; culms 20 to 100 cm. long, the nodes densely 

 pubescent; sheaths shorter than the internodes or sometimes nearly equal, densely 

 ciliate, otherwise glabrous or hirsute toward the summit; ligules less than 0.5 mm. long; 

 blades ascending or spreading, oblong-lanceolate, 3 to 13 cm. long, 8 to 15 mm. wide, 

 usually ciliate at the cordate base, otherwise glabrous or occasionally sparsely hirsute; 

 panicles 7 to 20 cm. long, about half as wide, the lower branches solitary, distant, 

 spreading, the upper sometimes in pairs, the numerous raceme-like branchlets secund 

 from the lower side of the branches, the somewhat clustered, short-pedicled spikelets 

 also secund on the branchlets, the rachises sparsely pilose with long, weak hairs, or 



a Syn. PI. Glum. 1 : 71. 1854. 



b Mem. Acad. St. Petersb. VI. Sci. Nat. 1: 266. 1834. 



cBiol. Centr. Amer. Bot. 3: 486. 1885. 



