Mapping is provisional pending deeper investigation. Following recent revision by Folk (2015; see also W), this species now appears to be centered in the Shawnee Hills, where if occurs only below sandstone cliffs. But it reportedly extends to disjunct populations, locally on limestone or dolomite, in se. Mo. and perhaps into the southern Cumberland Plateau. There has been much confusion in previous treatments with the largely Appalachian parviflora (Sm, F, St; Y, Wells 1983; FNA 8), and there may still be plants with dubious or intermediate status. Folk has identified some colls. from sandstone cliffs in Appalachian regions as missouriensis (e.g. by C.F. Reed from ELLI at MO and several from Tenn.), but these records remain dubuious. H. missouriensis reportedly differs in its shorter styles (exserted ca. 1-1.2 mm versus 1.75-2 mm), more condensed inflorescence (with pedicels mostly 3-5 mm versus 5-8 mm), subhorizontal flowers (versus pendent), which may open earlier (mostly Jul-Aug versus Sep-Oct), and perhaps (FNA 8 etc.) generally glandular-puberulent petioles and pedicels (versus villous). The name H. puberula Mackenzie & Bush has also been misapplied to some of these plants in Ky., but that species now appears largely restricted to more base rich substrates in the Ozark region. H. puberula reportedly differs in its more coriaceous leaves, petioles and hypanthia glandular-puberulent with 0.2-0.6 mm hairs (versus usually glandular-villous with 0.7-2.5 mm hairs but occasionally puberulent), and bracts usually entire (versus trifid). However, identification using these characters can sometimes be difficult. All three species often have pinkish or purplish lower leaf surfaces.