1921] Wiegand, — Echinochloa in North America 53 



a. First floret without a palet, neutral; lower glume distant 

 from the upper, narrow; ligule a row of hairs; coarse 

 glabrous perennial plants of wet places; (spikelets 

 large, 6-8 mm. long, ellipsoid not turgid, very min- 

 utely echinate or unarmed, short-awned, upper glume 

 often awn-pointed; awn of lemma (l-)2-4 cm. long; 

 panicle usually large, broad and dense, with copious 

 nodal and branch-setae; anthers 1.1-1.4 mm. long). 



9. E. holciformis. 

 a. First floret with a palet, staminate; lower glume inserted 

 close to the upper; ligule a row of hairs or wanting; 

 coarse glabrous or hairy perennial plants of wet places; 

 (spikelets ovoid or elliptic-ovoid, the ribs all nearly 

 equally and finely echinate; awn of lemma short or 

 none; panicle large but rather narrow). 

 b. Ligule a line of hairs. 



c. Spikelets 4.8-6 mm. long, short-awned; coriaceous 

 lemma 4-5 mm. long; anthers 2 mm. long; nodal 

 and branch-setae of the panicle usually copious; 

 leaf-blades 15-25 mm. broad; sheaths usually 



hairy; nodes densely hairy 10. E. polystachya. 



c. Spikelets 3-3.8 mm. long, awnless or nearly so; 

 coriaceous lemma 2.5-3 mm. long; anthers 1 mm. 

 long; nodal and branch-setae moderately devel- 

 oped; leaf-blades 5-10 mm. broad; sheaths and 



nodes glabrous 11. E. guaddoupensis. 



b. Ligule wanting, but ligular region often pubescent; 

 (anthers 1-1.5 mm. long; spikelets short-awned or 

 awnless; branches of panicle with few or no setae; 

 nodal hairs medium; leaf blades 8-30 mm. broad; 

 nodes and sheaths glabrous). 

 c. Spikelets 3.5-3.8 mm. long, 1.8-2 mm. broad, green. 



12. E. paludigena. 

 c. Spikelets 2.8-3.5 mm. long, 1.4-1.5 mm. broad, 

 usually purple-tinged ; branches of the panicle less 

 densely flowered var. soluta. 



1. E. colonum (L.) Link, 1 Hort. Berol. ii. 209 (1833). Panicum 

 colonum L. Syst. ed. 10. 870 (1759). — A weedy grass in damp culti- 

 vated fields and waste places: South Carolina, Tennessee and Ar- 

 kansas to Florida, Texas and southern California, also in Mexico, 

 Central America and the West Indies; almost cosmopolitan in the 

 warmer countries; sporadic in the northeastern states (Charlotte, 

 Vermont, Pringle; Philadelphia, Parker). 



Forma zonalis (Guss.) comb. nov. Panicum zonule Guss. Fl. 

 Sic. Prod. i. 82 (1827). P. colonum, var. zonule L. H. Dewey, Contr. 

 U. S. Nat. Herb. ii. 502 (1894). Echinochloa zonalis Pari. FL Panorm. 

 i. 119 (1839). — Leaves cross-banded with purple. Massachusetts, 

 Texas, Arizona, and probably elsewhere. Specimens examined: 

 Massachusetts: Amherst, "ornamental," 1875, W. H. Blanchard. 

 Texas: about Kerrville, 1894, A. A. Heller, no. 1,923. Arizona: 

 Chiricahua Mountains, 1907, J. C. Blumcr, no. 2,268. 



1 Hitchcock, following Greene, has called attention to the fact that the name 

 colonum is not an adjective and hence should not be declined (see Mex. Grasses, 

 Contr. U. S. Nat. Herb. xvii. pt. 3, 256, 1913). 



