This tetraploid (2n = 42) is widespread in eastern North America. But it is less common on the southeastern Coastal Plain, where largely replaced by the more robust segregate, A. altissima (Walt.) Tuckerman (= A. elata Trin.). A. altissima has been reported from Ky. under various names by Kearney (1893) and others (M), but no colls. have been located. It occurs in bogs on the Coastal Plain from N.J. to Fla. to se Miss. and it is very unlikely to occur in Ky. (W). Some colls. (at MUR) from CARL and FULT are referable to A. perennans var. aestivalis Vasey, but that taxon has not been recognized in recent treatments (FNA 24). Based on F and Ladd & Thomas (2019), var. aestivalis has a more northern range and differs as follows: plants relatively tall but few-stemmed and often decumbent; ligules 1-3 mm (versus 2.5-5 mm); panicles very laxa with divergent branches (versus ellipsoid to ovoid with divergent to ascending branches); many of the spreading pedicels 1-3 times length of spikelets (versus appressed-ascending, mostly shorter or equaling); spikelets ca. 1.5-2 mm (versus 2-3 mm). L & T state: "occurs in high quality shaded wetlands in the Ozarks". Kearney (1893) also described A. intermedia Kearney from BELL or HARL, but the type (at Ohio State Univ.) is not distinct from perennans, and he did not list perennans.