THE NORTH AMERICAN SPECIES OF PENNISETUM. 



227 



Gymnothrix grisebachiana Fourn. Mex. PI. 2: 48. 1886. "Mirador (Schaffn[er] 

 n. 185. pi. ed. Hohen.)." A specimen of Schaffner's no. 185 was examined by A. S. 

 Hitchcock in the Grisebach Herbarium at Gottingen. 



Pennisetum mexicanum Hemsl. Biol. Centr. Amer. Bot. 3: 508. 1885, nom. nud.; 

 Ind. Kew. 2: 458. 1894. Based on Gymnothrix mexicana Fourn. 



DESCRIPTION. 



Plants perennial; culms solitary or few together, erect or ascending from a strong 

 rhizome, 1 to 2 meters tall, sometimes dwarfed, scabrous below the panicle, otherwise 

 glabrous, simple or, more commonly, with one or two, rarely with several, flowering 

 branches, the lower nodes sometimes geniculate, the internodes terete (or the lower 

 slightly compressed) slightly or not at all channeled, not elongate and naked; sheaths 

 loose, commonly as long as the internodes or longer, pilose on the margin at the sum- 

 mit, sometimes pubescent on the collar; ligule ciliate, about 2 mm. long; blades 

 thinner than in P. crimtum, mostly somewhat spreading, flat, or folded at base, 20 to 55 

 cm. long, 5 to 8 or rarely 10 mm. wide, glab- 

 rous beneath, very scabrous on the upper 

 surface, often papillose-pilose toward the base 

 and with stiff hairs just back of the ligule, 

 attenuate into an elongate involute setaceous 

 tip; panicles nodding or somewhat flexuous, 

 7 to 16 cm. long, about 10 to 12 mm. thick, 

 excluding the longest bristles, not so dense as 

 in P. crinitum, with tawny or purplish bristles 

 and pale spikelets, the slender axis ridged 

 and scabrous; fascicles on very minute 

 bearded peduncles, ascending; bristles ntf 

 -merous, unequal, most of them exceeding 

 the spikelet, several to many, 12 to 15 mm. 

 long, the innermost 15 to 25 mm. long, but 

 usually not conspicuous as in P. crinitum; 

 spikelet solitary, sessile, 6 to 7 mm. long, 

 about 1.8 mm. wide.rather abruptly pointed, 

 minutely scaberulous: first glume one-fourth 

 to one-third the length of the spikelet, thin, 

 1-nerved, acute to truncate; second glume two- thirds to three-fourths as long as the 

 fruit, 5-nerved, acute or subacute; sterile lemma slightly shorter than the fruit, 

 5-nerved, acuminate, inclosing a palea of equal length and usually a staminate 

 flower; fruit rather less indurate than in P. crinitum, acuminate-tipped, the tip of 

 the palea free. 



DISTRIBUTION. 



Open, rather dry slopes and savannas from near sea level to 1,500 meters altitude 



from southern Mexico to Panama. 



Veracruz: Orizaba, Bourgeau 3139; Hitchcock 6356; Mohr in 1857; Muller 2015, 

 Smith 625. Papantla, Liebmann 344. Mirador, Schaffner 185. 



Guatemala: Coban, Tiirckheim 81, 445, 3835. Guatemala City, Hitchcock 9042, 9043, 

 9058: Popenoe 734. Eureka, Hitchcock 9077. Laguna de Ayarza, Heyde & Lux 

 3923^ Salida de Izabel, Seler 2301. Antigua, Kellerman 5112. Lake Amatitlan, 

 Kellerman 6248. 



Salvador: Sonsonate, Hitchcock 8973. Izalco, Pittier 1901a. Volcano of San Sal- 

 vador, Hitchcock 8943. 



Panama: El Boquete, Hitchcock 8250. 



Fig. 



71. — Pennisetum complanatum. 

 Tiirckheim 3835, Guatemala. 



From 



