This taxon may be distinguished from engelmannii (W) by its velum, "a thin flap of tissue completely or partially covering the adaxial wall of the sporangium" (FNA 2). The velum of valida reportedly covers 40-70% or "uncommonly to ± 30%" (W); in typical engelmanni the coverage is less than 40%. I. valida is reportedly a less robust plant than engelmannii sensu stricto, with spores that are more spinulose. It has been described as more emergent (versus emergent or aquatic) and typical of more stagnant to oligotrophic waters, typically in "woodland seepages" and often with Sphagnum (F, W). However, valida was not recognized at species or variety level by FNA 2. A coll. by G. Libby from MCRE (ODU) has been determined by L.J. Musselman as valida (see also K), but confirmation is needed. Several related polyploids have been recently described in southeastern states, including I. appalachiana D.F. Brunton & D.M. Britton. That taxon is reprtedly a tetraploid derived from engelmanii and valida that is concentrated on the Coastal Plain from Ala. to N.J., but it may be expected in Ky. (Brunton & Britton 1997; K, W). According to K (in progress), citing Brunton pers. comm., a coll. from EDMO (VPI) has been referred to appalachiana. The three species of Isoetes currently verified in Ky. are reportedly all distinct diploids (2n = 22), but there may be no actual data on ploidy from Ky. plants.