28 CONTRIBUTIONS FROM THE NATIONAL, HERBARIUM. 



Ecuador: Between Rio and Salto, Jameson in 1864. Gualea, Sodiro 3118, 3121. 

 Bolivia : Guanai, Rusby 191. Cochabamba, Bang 1289, 1291. 

 Argentina : Misiones, Ekman 617, 619. 



Explanation of Plate 22. — Lasiacis sorghoidea. Specimen from Mayaguez, Porto 

 Rico, Holm 116 (U. S. Nat. Herb. no. 733619). Natural size. 



14. Lasiacis ruscifolia (H. B. K.) Hitchc. 



Paivicum ruscifoUum H. B. K. Nov. Gen. & Sp. 1 : 101. 1816. " Crescit in 

 apricis et aridis Regni Mexicani, in radicibus montis ignivomi, Volcan de 

 Jorullo." 



Panicum compactum Swartz, Adnot. Bot. 14. 1829. Not P. compactum Kit. 

 1814. This was briefly described after Swartz's death by Wikstrom, who con- 

 sidered it distinct from Panicum divaricatum L. because of the dense panicle 

 and wide blades. The specimen in the Swartz Herbarium at Stockholm is a 

 single shoot with three leaves and an ovoid panicle about 8 cm. long. The 

 spikelets are 3 to 3.5 mm. long. 



Panicum megacarpum Steud. ; Griseb. Fl. Brit. W. Ind. 551. 1864. This name 

 is given by Grisebach as a synonym of P. lanatum /3 sorghoideum and credited 

 to " Steud. in PL Lechler, 2219." 



Panicum liebmamiianum Fourn. Mex. PI. 2: 33. 1886. " Consoquitla (Liebm. 

 n. 299)." The type has been examined in the Copenhagen Herbarium. The 

 panicles are narrow and compact, the blades pubescent beneath and minutely so 

 above, the spikelets about 3.5 mm. long. 



Lasiacis compacta Hitchc. Bot. Gaz. 51: 302. 1911. Based on Panicum com- 

 pactum Swartz. 



Lasiacis ruscifolia Hitchc. Proc. Biol. Soc. Washington 24: 145. 1911. Based 

 on Panicum ruscifoUum H. B. K. 



Lasiacis liebmanniana Hitchc. Proc. Biol. Soc. Washington 24: 145. 1911. 

 Based on Panicum liebmannianum Fourn. 



DESCRIPTION. 



More robust than any other species, freely branching, the shoots usually 

 strongly dorsiventral ; culms becoming several meters long, glabrous or rarely 

 puberulent ; sheaths often overlapping, glabrous on the surface or sometimes 

 hispidulous toward the apex (in some Central American specimens papillose- 

 hispid throughout), glabrous or often ciliate or villous on the margin, espe- 

 cially near the summit, the collar glabrous or villous ; ligule inconspicuous ; 

 blades ovate-lanceolate or elliptic, sometimes lanceolate, the primary ones 

 10 to 15 cm. long, 3 to 6 cm. wide, narrowed or often cordate-clasping at the 

 asymmetric base, rather abruptly narrowed to an acuminate but not attenuate 

 apex, puberulent or glabrous beneath, glabrous or scabrous above, the sec- 

 ondary blades similar or reduced; panicles narrow and compact, 5 to 20 cm. 

 long, or often with distant lower branches, these compactly flowered, or the 

 panicle rarely somewhat open, with spreading, implicate but rather closely 

 flowered branches, the axes hispidulous and scabrous; spikelets 3 to 4 mm. 

 long, nearly globose at maturity. 



This species is variable as to pubescence, and the panicles, at first dense, 

 may with age become rather open. The blades are usually cordate and some- 

 what clasping and proportionately wider than in any other species. The 

 specimens from the West Indies and Mexico have the blades pubescent be- 

 neath, but from Central America there are many specimens with glabrous 

 blades. The latter region furnishes also specimens with papillose-hispid 

 sheaths, in which the blades may be glabrous or pubescent beneath. 



