This widespread northeastern tree is now much declined across its range due to "butternut canker" fungus in the bark (Orchard 1984). A recent survey in the southern Great Lakes region found that older maple/beech/birch stands on uplands may provide best continued survival (Morin et al. 2018). But in Canada disease appears less problematic for open-grown or dominant trees, especially in cooler regions (Sambaratu et al. 2018). In Ky. documentation with colls. is rather poor; included here as open dots are the unverified historical data of Gm and B. The species has virtually disappeared from some regions of the state, and it remains locally frequent only on fertile mesic sandy terraces of some Appalachian valleys. In morphology and nuclear DNA, cinerea appears closely related to the East Asian walnuts; see notes under ailantifolia. However, its chloroplasts are most similar to nigra, suggesting transferance across clades during past evolution (Dong et al. 2017). There are several chloroplast haplotypes, with generally distinct ranges, but Ky. and Tenn. may be a center of diversity (Laricchia et al. 2015).. Trees of cinerea are easily distinguished from nigra by their distinctive gray-white bark. Also, the oval to ellipsoidal fruits are clammy with glandular hairs; there is much variation in shape even within populations. Twigs can be distinguished from nigra by their usually longer terminal buds, up to 12-18 mm on vigorous growth (versus 8-10 mm), and the upper sides of bud scars almost straight (versus distinctly notched), with a distinct velvety fringe; surface color is usually paler (light gray-gray brown versus medium-dark gray or brownish), but not distinct as in mature trees; pith is dark brown (versus light brown). Leaves usually have 11-17 leaflets (versus 15-19), with some 4-8-rayed hairs below (versus only single and 2-rayed hairs) and oblong-tending shape (versus ovate-tending). The terminal leaflet is usually well developed; in nigra it is usually much smaller or aborted. Although cinerea can often become widely branching, relatively tall trees do occur in deeper woods. The state champion is reported from PIKE: 159 cm dbh, 23 m tall and 16 m wide (KDF 2020).