GRASS FAMILY 



111 



1. Paspalum distichum L. 



Knot-grass. Fig. 226. 



Paspalum distichum L. Syst. Xat. ed. 10. 2: S55. 1759. 



Culms erect from a decumbent rooting base, with 

 numerous creeping rhizomes, glabrous, or the nodes 

 pubescent, 30-60 cm. tall ; sheaths glabrous or some- 

 times pubescent ; blades flat, glabrous, rarely pubescent, 

 5-10 cm. long, the upper shorter ; racemes 2, paired 

 or closel}- approximate, sometimes a third below the 

 second, more or less pilose at base, slender, ascending 

 or appressed, usually 2.5-5 cm. long ; spikelets elliptic, 

 3 mm. long; first glume occasionally present and 

 nearly as long as spikelet, glabrous ; second glume 

 pubescent ; sterile lemma glabrous. 



Along the seacoast and especially along irrigation ditches 

 and wet places in the interior, California, and occasionally 

 along the Columbia River. June-Sept. Type locality: Jamaica. 



2. Paspalum dilatatum Poir. 

 Dallis Grass. ¥\g. 227. 



Paspalum dilatatum Poir. Lam. Encycl. 5: 35. 1804. 



Culms few to many, tufted, erect, or geniculate at 

 base, 1 meter or more tall, glabrous ; sheaths loose, 

 glabrous or the lowermost softly pubescent ; ligule 

 about 3 mm. long; blades flat, 5-12 min. wide, com- 

 monly elongate, pilose on the upper surface at the 

 base, otherwise glabrous ; panicle 10-20 '^m. long, the 

 common axis slender ; racemes mostly 5-10. densely 

 flowered, 5-10 cm. long, the rachis narrowly winged ; 

 spikelets in pairs, ovate, abruptly pointeo, 3-3.5 mm. 

 long ; 2-2.3 mm. wide, flat, the margins of the second 

 glume and sterile lemma, especially the glume, with 

 long silky white hairs. 



Ballast, Portland, Oregon, and roadsides, Los Angeles, 

 California. Introduced from South America; cultivated in the 

 Oulf States and abundantly naturalized; rare on the Pacific 

 Coast. July-Oct. Type locality: Argentina. 



3. Paspalum larranagai Arechav. 

 \asey Grass. Fig. 228. 



Paspalum virgatuDi pubiflonim Vasey, Bull. Torrey Club 13: 

 167. 1886. 



Paspalum larranagai Arechav. Anal. Mus. Nac. Montevid. 1 : 



60. pi. 2. 1894. 



Paspalum vascyanum Scribn. U. S. Dept. Agr. Div. Agrost. 

 Bull. 17: 32. /. 328. 1899. 



Resembles P. dilatatum, culms usually more robust ; 

 lower sheaths hirsute, the upper hirsute on the mar- 

 gins; panicles commonly more than 15 cm. long, 

 racemes 10-25 (rarely fewer) ; spikelets 2-2.2 mm. 

 long, the silky hairs longer and more copious than 

 in P. dilatatum. 



Along irrigation ditches, California. Introduced from 

 South America; open low ground from Texas to South Caro- 

 lina, spreading rapidly. Aug.-Oct. Type locality: Uruguay. 



