HITCHCOCK AND CHASE NORTH AMERICAN PANICUM. 99 



Panicum caricoides Nees,a^ the type specimen of which, in the Munich Herbarium, 

 was collected by Martins in the province of Para, Brazil, is an allied species. The 

 Martius specimen differs from the West Indian plants in having larger spikelets, 1.8 

 to 1.9 mm. long, and numerous long, stiff, erect hairs on the pedicels. 



DISTRIBUTION. 



Borders of ponds and wet savannas, Costa Rica and the West Indies; also in Brazil. 

 Costa Rica: Buenos Aires, Pittier 10589. 

 Cuba: Herradura, Baker & Dimmock 4837 (Hitchcock Herb.), Hitchcock 155; 



without locality, Wright 3871; Hanabana, Wright 192 (Grisebach Herb.). 

 Santo Domingo: Wright, Parry, & Brummel 624. 

 Brazil: Prov. of St. Paul, St. Hilaire 758 (Paris Herb.); Barra, Spruce 1289 (Gray 



Herb.). 



Agrostoidia. — Tufted perennials; culms erect, compressed, sheaths more or less 

 keeled; ligules membranaceous, short, sometimes ciliate; blades long and 

 narrov/; spikelets lanceolate, glabrous; first glume keeled, scabrous on the 

 keel toward the apex, the second glume and sterile lemma pointed beyond 

 the fruit, more or less keeled, the spikelet thus often appearing laterally 

 compressed, the palea of the sterile floret about half as long as its lemma; 

 fruit elliptic, smooth and shining, a minute tuft of thickish hairs at the apex. 

 The first three species of this group have much the appearance of certain 

 species of Agrostis. 

 Rootstocks present; culms but little compressed; spikelets set 

 obliquely on their appressed pedicels. 

 Panicles open; spikelets 3.4 to 3.8 mm. long (shorter in 



exceptional specimens) 55. P. anceps. 



Panicles more or less contracted; spikelets not over 2.8 



mm. long 56. P. rhizomatum. 



Rootstocks absent; culms strongly compressed with keeled 



sheaths; spikelets not obliquely disposed. 



Ligules ciliate; basal leaves half as long as the culm or 



more; panicle much exceeding the upper leaves. 



Spikelets not over 2.7 mm., usually 2.5 mm. long, the 



first glume less than half that length ; ligules 2 



to 3 mm. long 53. P. longifolium. 



Spikelets 3 to 3.5 mm. long; first glume two-thirds to 

 three-fourths that length; ligule less than 1 



mm. long 54. P. combsii. 



Ligules erose or lacerate, not ciliate; basal leaves in short 

 tufts, the upper usually nearly equaling the terminal 

 panicle. 

 Fruit stipitate; spikelets 2.5 to 2.8 mm. long, con- 

 spicuously secund 52. P. stipitatum. 



Fruit not stipitate; spikelets not conspicuously se- 

 cund. 

 Spikelets 1.8 to 2 'torn., in occasional specimens 

 2.2 mm. long; panicle branches ascending 



or spreading 50. P. ugrostoides. 



Spikelets about 2.5 mm. long; panicle branches 



erect or nearly so 51. P. condensum. 



a Nees in Trin. Gram. Pan. 149. 1826; Nees, Agrost. Bras. 108. 1829. 



