Twenty native Ohio vascular plant taxa, previously considered for review by the United States Fish and Wildlife Service as possibly federally endangered or threatened, were studied over a two-year period to assess their rarity and threat of extirpation, nationally and in Ohio. Current information indicates that Aconitum noveboracense should be maintained as federally threatened, and that Calamagrostis insperata, Plantago cordata, and Platanthera leucophaea should be considered for listing as federally threatened. Current data on the status of Poa paludigena, Potamogeton hillii, Synandra hispidula, and Trollius laxus are too limited to make an adequate recommendation as to possible federal status. Although rare in Ohio, Cypripedium candidum and Veratrum woodii are apparently more frequent elsewhere and presently do not warrant listing. Unresolved taxonomic problems prevent specific recommendations for Polygonum pensylvanicum var. eglandulosum, and Rhus trilobata var. arenaria. Taxa frequent throughout much of their ranges, including Ohio, that do not appear to warrant listing are Panax quinquefolius, Platanthera flava, Platanthera peramoena, Polemonium reptans var. villosum, and Sullivantia sullivantii. Hybrids that do not meet the definition of “species” under the Endangered Species Act are Asplenium ✕ ebenoides, Asplenium ✕ kentuckiense, and Muhlenbergia ✕ curtisetosa.