This segregate of amoena is known only from open boulder-cobble bars along the Big South Fork of Cumberland Rv. (in MCRE. Ky., and Scott Co., Tenn.), and along the Obed Rv. (Morgan Co., Tenn.), plus major tributaries of these streams. These plants were initially referred by JC and MM in error to P. pilosa var. detonsa (Gray) Wherry, which is a glabrous plant of pine woods further south. Typical amoena occurs on adjacent uplands, but is generally absent on the river bars. In these plants on the bars, leaves below the inflorescence are largely glabrous, except for the margins of petiolar bases; stems are thinly hirsute. In typical amoena, leaves and stems are densely hirsute. Also, stoloniferous spread is more pronounced in these plants (Zale 2014). Local adaptation to stream-scouring (rheophytic) conditions is also known in P. pilosa ssp. sangamonensis Levin & D.M Smith of c. Ill., and in P. pilosa var. riparia Wherry on the Edwards Plateau in Tex. (Wherry 1955; Cr).