This rather obscure species is known only from flatwoods and siltstone barrens in s. Ind. and perhaps s. Ill. (FNA 17). It is close to alluviorum, differing in its sepals only 2-4 mm long (versus 5-9 mm) and scarious margined (versus not or scarcely so); also, its lower leaves are rounded at the apex and entire or slightly denticulate (versus acuminate and rather sharply serrate). P. deamii was reported from HARD by Cranfill (1989), but the coll. may be lost or still unprocessed.