This diploid (2n = 36) is largely concentrated in coastal regions of southeastern states and near the Great Lakes (FNA 25, K). Occasional inland records may partly result from dispersal by migrating waterfowl. Seeds of Echinochloa species are important food for waterfowl populations during the winter, especially on shorelines, wet fields and similar managed "moist soil" habitats. Plants generally need at least 2-3 months of flood-free growing season to produce abundant seed (Ahn et al. 2004)..The few scattered records of walteri from Ky. mostly deserve more confirmation: Kearney (1893) from BELL or HARL; Gunn (1968) from BULL; A. Cusick (NCU) from GALL; and L. McKinney (VDB) from FULT. There is also an old coll. by C.W. Short (WIS) but without state or locality noted. E. walteri is close to muricata but differs as follows (FNA 25, W): upper (fertile) lemmas narrowly ovate to elliptic with L/W about 2.5-4 (versus broadly obovoid to orbicular, with L/W about 1.5-2.5); lower (sterile) lemmas with awn up to 25+ mm long (versus 10-16 mm); spikelets scabrous to hairy, but not papillose-based (versus usually hispid with papillose-based hairs); panicle branches loosely erect (versus usually spreading and rather distant), their nodes with hairs up to 3.5-5 mm long (versus 3 mm); lower sheaths usually papillate-pubescent (versus glabrous); plants generaly more robust (to be detailed), with blades up to 55 cm long (versus 30 cm) and 3-6 cm wide (versus 2-3 cm).