THE NORTH AMERICAN SPECIES OF PENNISETUM. 



233 



spike] ets are 5 mm. or more long. A specimen of that collection in the herbarium 

 at Vienna is labeled " Pcnnisetum tristachyum var. Galeottianum T.eeke, n. var." and 

 is probably the type. Galeotti's no 5871 differs from other specimens of P. ba'mbusi- 

 forme in that the sterile floret is empty in about half the spikelets examined. Other- 

 wise the specimen has the characters of this species. 



DESCRIPTIONS 



Plants perennial, the culms very robust, probably as much as 6 meters tall (the 

 base not seen), glabrous, branching from the upper nodes, the branches often in fas- 

 cicles of 2 or 3 (on the average less numerous than in P. prolificurrk slender, repeatedly 

 branching, the whole forming a drooping compound leafy inflorescence, looser and 

 less massive than in P. prolificum: nodes glabrous, rarely appressed-pubescent; 

 sheaths loose, ciliate on the margin and with an erect tuft of white hairs at the summit 

 (old sheaths commonly glabrescent), the sheaths of the inflorescence on the average 

 longer than in P. proUflcum and somewhat in- 

 flated; ligulfc lacerate-ciliate, about 2 mm. 

 long: blades flat, rather firmer than in the two 

 preceding species, ascending or spreading, 

 those of the main culm 20 to 35 cm. long, 2 to 

 3.5 cm. wide, narrowed, sometimes somewhat 

 attenuate at base, scabrous or appressed- 

 pubescent on the upper surface, softly ap- 

 pressed-pubescent beneath, sometimes gla- 

 brescent, the blades of the ultimate branch- 

 lets narrow, much reduced; peduncles slender, 

 scaberuous, flexuous, unequal, one panicle of 

 the fascicle partly included; panicles purplish 

 taw r ny, 5 to 12 cm. long (rarely longer), about 

 1 cm. wide, excluding the longest bristles, 

 loose, flexuous, tapering at the apex:, the 

 slender angled axis scabrous or hispidulous: 

 fascicles on minute pedicels, not crowded, 

 ascending; bristles slender, flexuous, numer- 

 ous, very unequal, most of them about twice 

 the length of thespikelet, the innermost some 

 times as much as 2 cm. long; spikelets 5 to 8 

 mm. long, 1 to 1.2 mm. wide, scabrous; 

 glumes unequal, the first minute, usually 

 nerveless, obtuse or erose, the second one- 

 fourth to one-third the length of the spikelet, 1 to 3-nerved, acute or erose; sterile 

 lemma exceeding the fertile lemma, 5 to 7-nerved, attenuate into a slender flexuous 

 tip, inclosing a well-developed palea and usually a staminate flower; fruit 4.5 to 5 

 mm. long, the lemma scabrous toward the acuminate apex, but slightly indurate. 



DISTRIBUTION. 



On rocky slopes and cliffs, between 900 and 2,800 meters altitude, southern Mexico 

 to Peru. 



Veracruz: Mirador, Liebinann 338. Petlapa, 47 Liebmann 340. 

 Oaxaca: Comal tepee, Galeotti 5871. 



Fig. 76. — Pennisetum bambusiforme. 

 Jimenez 990, Costa Rica. 



From 



47 We are unable to locate this station, but most of Liebmann's collections were 

 made in Veracruz. It may be in Oaxaca. 



183104—20—3 



