This occurs mostly along rocky riverbanks in the Ozarks and Ouachitas. Appalachian localities in Ky., Tenn., Ala. and Ga. are highly disjunct from the main range of this species. It was recently discovered along the Big South Fork in MCRE (EKY) by N. Drozda and others of KSNPC. In Tenn. it is known from several other sites further up this river and along the Obed Rv. There is molecular evidence that Calamovilfa could be included within a broadly defined Sporobolus, but treatment remain somewhat uncertain (W). Calamovilfa may be distinguished as follows (FNA 25): florets with calluses evidently hairy, the hairs 1/4 - 7/8 as long as the lemmas (versus glabrous or nearly so); paleas hairy, longitudinally grooved (versus glabrous, 2-veined and often splitting between veins); fruits falling with the lemma and palea (versus falling free but with pericarp often becoming mucilaginous); inflorescence exerted (versus exerted or included in sheaths); plants rhizomatous (versus usually cespitose); x = ?10 (versus 9).