Echinochloa

1. Leaf sheaths (at least the lower ones) ± rough-hairy (very rarely smooth); spikelets each with 2 awns (one on sterile lemma, one on second [larger] glume).

E. walteri

1. Leaf sheaths smooth, essentially glabrous; spikelets usually with usually 1 awn (on sterile lemma, the second glume ± acuminate, rarely short-awned) or without awn.

2. Polished body of fertile lemma tapered into the firm tip without sharp demarcation or pubescence; stiff bristles of second glume and sterile lemma often with pustulate bases.

E. muricata

2. Polished body of fertile lemma sharply demarcated from withered green tip by a fringe of minute pubescence [20×] in a ± straight line on the shiny part; stiff bristles of second glume and sterile lemma seldom with pustulate bases.

3. Inflorescences with branches clearly visible throughout; sterile lemma awned or not.

E. crusgalli

3. Inflorescences with lateral spikes congested, the upper ones in the inflorescence forming a ± dense elongated head, the branching not discernable; sterile lemma not awned.

E. esculenta

All species found in Echinochloa

Echinochloa crusgalliBARNYARD GRASS 
Echinochloa esculentaJAPANESE MILLET 
Echinochloa muricataBARNYARD GRASS 
Echinochloa walteriSALT-MARSH COCKSPUR GRASS 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. March 27, 2017. http://michiganflora.net/genus.aspx?id=Echinochloa.