HITCHCOCK AND CHASE — NORTH AMERICAN PANICITM. 71 



axillary from the upper 2 or 3 sheaths, rarely fascicled, approximate and forming an 

 elongated inflorescence from two-thirds to almost the entire height of the plant, the 

 individual panicles ineluded at the base, 8 to 20 cm. long, half to two-thirds as wide, 

 the slender, scabrous branches and branchlets and the long, flexuous pedicels divar- 

 icate; spikelets 2.2 to 2.3 mm. long, 1.2 mm. wide, obovoid, turgid; first glume about 

 half the length of the spikelet, acute; second glume and sterile lemma equal, slightly 

 exceeding the fruit, abruptly short-pointed, strongly 5 to 7-nerved, the sterile palea 

 about half the length of its lemma; fruit 1.7 mm. long, 1.1 mm. wide, oval, turgid. 



In its elongated inflorescence composed of several approximate panicles this species 

 resembles P. rudgei Roein. & Schult., with which it has commonly been confused. 



DISTRIBUTION. 



Pine woods, Costa Rica, Cuba, and South America. 



Costa Rica: Buenos Aires, Tonduz 3685. 



Cuba: Pinar del Rio, Wright 3865; Herradura, Tracy 9073; Isle of Pines, Curtiss 



267, Palmer & Riley 1086, Taylor 34. 

 French Guiana: Cayenne (Paris Herb.). 

 Brazil: Burchell 8350. 



Diffusa. — Perennials; culms stiff, somewhat tufted, sheaths mostly hirsute, ligules 

 membranaceous, ciliate, 1 to 3 mm. long; blades long and narrow; spikelets 

 mostly narrowly ovate, acuminate, glabrous; first glume clasping, the equal 

 second glume and sterile lemma exceeding the fruit and pointed beyond it, 

 the palea of the sterile floret about half as long as its lemma; fruit smooth and 

 shining. The species of this group often resemble those of Capillaria, espe- 

 cially in their spikelets, but the latter are all annual. 

 Second glume and sterile lemma elongated, at least three 



times as long as the fruit 32. P. capillarioides. 



Second glume and sterile lemma not elongated. 



Panicles narrow, compact; blades 2 cm. or more wide. . . 38. P. hirsutum. 

 Panicles diffuse, at least at maturity; blades not over 1 

 cm. wide. 

 Blades 1 to 3 mm. wide, plants spreading or ascending 33. P. diffusion. 

 Blades mostly over 5 mm. wide, plants erect. 



Spikelets 4 to 4.2 mm. long, the midnerves of 

 glumes and sterile lemma scabrous toward 



the apex 36. P. lepidulum. 



Spikelets usually less than 3.5 mm. long. 



Blades hirsute on both surfaces (sometimes 



giabrescent), not at all glaucous 37. P. ghiesbreghtii. 



Blades glabrous on both surfaces or with a 



few hairs on either surface, glaucous 



above. 



Panicles much exceeding the leaves; 



spikelets 3 to 3.5 mm. (rarely 3.7 



mm.) long 35. P.hallii. 



Panicles usually equaled or exceeded by 

 the uppermost blades; spikelets 2 

 to 2.6 mm. long 34. P. filipes. 



