This unusual globally endangered biennial is known mostly from c. Ky. and c.Tenn. Also, disjunct plants occur along a gravel road through bottomland woods in sw. Ind.; this population is indistinguishable from Ky. plants based on DNA (C. Edwards, pers. comm.). Old records from Ark., Mo., and Ohio remain unverified (Gray 1889, F, Al-Shehbaz 1987, FNA 7). See O'Kane & Al-Shehbaz (2002; and other citations in W) for support of generic realignments. In Ky., under the name Vesicaria shortii Torr. ined., Short (1837) noted: "This very rare plant, of which we have only met with two imperfect specimens, on Elkhorn Creek between Lexington and Frankfort, is considered by Dr. Torrey a new species." There is also an old coll. by Short or associates from "banks of Kentucky River, Frankfort, May 1856" (GH). But in 1914, Gm noted: "growing abundantly on waste land along railroads, etc." There are also remarkable colls. from POWE (GH) in 1874 and 1923, near Natural Bridge; presumably it grew along the access road with limestone gravel. Within Ky. Physaria is now largely restricted to a few sites in rocky woods of the central Bluegrass region, where thin or eroded soil supports small populations; it occurs with Trifolium kentuckiense in FRAN. Only a few waifs in landscapes with deeper soils have been found during recent decades. It seems likely that animal trails or other disturbance promoted this species before settlement, but that reduction in wilder lands plus the invasion of competing European Brassicaceae and associated pests has now led to its precarious position. Nevertheless, the species can be locally established in suburban landscapes on rocky patios (C. Chandler, pers. comm.), along driveways (D. Svetich, pers. comm.), and similar sites; it is now an occasional "weed" in flower beds of JC. But seedlings sometimes suffer high mortality due to slugs or other herbivores, and the taproots are sensitive to damage or stress. Ky. plants appear to be less vigorous than Tenn. plants and begin to flower 2 weeks later (in April), based on initial comparisons in the garden of JC; however, seeds produced by a mixed planting from both states appeared to become more vigorous plants than seedlings from single states. The life-history and ecology of this species remains poorly documented; although experience in Ky. suggests it is typically biennial in nature (germinating in spring), some observations (at least from cultivation) indicate occasional winter-annual behavior (germinating in fall) or survival to flower in a third year (Long et al. 2017). Unfortunately, there has not yet been a complete synthesis of knowledge by people most familiar with this species. It is particularly important to understand this species' dependence on soil disturbance. This factor is virtually ignored by Long et al. (2017), who made the odd statement: "Soil disturbance should be minimized to maintain sites for ground-nesting pollinators." They also treated right-of-way maintenance as a threat, but such maintenance appears to be essential for the Ind. population and some others.