(117) Request for a binding decision on whether the names Hieracium greenei A. Gray and H. greenii Porter & Britton (Asteraceae) are sufficiently alike to be confused

(117) Hieracium greenei A. Gray (1883) [Angiosp.: Comp.] Hieracium greenii Porter & Britton (1893) [Angiosp.: Comp.] Gray (in Proc. Amer. Acad. Arts 19: 69. 1883) named Hieracium greenei to honour Edward Greene (1843–1915). This species is endemic to northern California and southwestern Oregon in the western United States. Porter & Britton (in Bull. Torrey Bot. Club 20: 120. 1893) described H. greenii to honour Traill Green (1813–1897). This species is endemic to Kentucky, Maryland, Ohio, Pennsylvania, Virginia, and West Virginia in the eastern United States. In Hieracium, the epithets greenii and greenei, although they honour two different people and apply to species that are endemic to distinct geographic ranges, are considered by some to be so similar as to cause confusion, and general (but not universal) practice has been to treat the two names as homonyms. Edward Greene (in Pittonia 4: 226. 1900) considered H. greenii to be a later homonym of H. greenei, and published H. traillii Greene as a replacement name (nom. nov.). This opinion has been followed by the authors of most, but not all, floristic works of the twentieth and twenty-first centuries covering the known range of H. greenii/traillii. Floras that adopt H. traillii include Gleason (Ill. Fl. N. U.S., ed. 3, 3: 525. 1952); Strausbaugh & Core (Fl. W. Virginia, ed. 2, 4: 1027. 1977); Brown & Brown (Herb. Pl. Maryland: 1065. 1984); Fisher (Dicot. Ohio 3: 260. 1988); Gleason & Cronquist (Man. Vasc. Pl. N.E. U.S., ed. 2: 624. 1991); Rhoads & Klein (Vasc. Fl. Pennsylvania: 404. 1993); Rhoads & Block (Pl. Pennsylvania, ed. 2: 899. 2007); Strother (in FNA Ed. Comm., Fl. N. Amer. N. Mexico 19: 293. 2006); Weakley & al. (Fl. Virginia: 346. 2012, Fl. S.E. U.S.: 1686. 2023). IPNI (ipni.org. 2024) and Tropicos (Tropicos.org. 2024) also treat H. greenii as illegitimate. The primary sources known to the author that treat H. greenii as legitimate are Porter (Fl. Pennsylvania: 306. 1903), and Kartesz (The Biota of North America Program [BONAP; bonap.org]. 2015). Other publications that follow BONAP taxonomy as a default treatment also use H. greenii, including USDA Plants (Plants.usda.gov. 2024); and until recently NatureServe (natureserve.org. 2024), where the name still appears in descriptions of ecological units pending updating to the currently accepted H. traillii (Wesley Knapp, pers. comm.). Hieracium greenii also appears in derivatives of the above publications (e.g., U.S. National Vegetation Classificaton [usnvc.org]. 2024); and certain NatureServe member organizations, e.g., Maryland NHP (Harrison, Nat. Communities Maryland [unpub. rep.]. 2016 [dnr.maryland.gov/wildlife/Documents/Natural_Communities%20_Maryland_2016_Framework.pdf]) and West Virginia NHP (Wild Veg. West Virginia. 2016 [wvdnr.gov/wp-content/uploads/2021/07/WVWV-Shale-Barrens.pdf]). Hieracium greenii can be found in some botanical literature from before 1960 (e.g., Bartholomew in Castanea 13: 145–167. 1948). The author found few instances of the use of Hieracium greenii in more recent literature, but a notable exception is a 1990 paper (Hill in Castanea 55: 211–212. 1990) where a case is made that H. traillii is superfluous. The salient points in that paper are that the two names are not spelled exactly the same, and do not represent orthographic variants, as they are named for different people who spelled their names differently. The Berlin Code (Greuter & al. in Regnum Veg. 118. 1988), in force in 1990, did not contain the admonition in Art. 53.2 of the Shenzhen Code (Turland & al. in Regnum Veg. 159. 1918), "If established practice has been to treat two similar names as homonyms, this practice is to be continued if it is in the interest of nomenclatural stability." Over the past 34 years, it has become increasingly in the interest of nomenclatural stability to treat Hieracium greenii as a homonym of H. greenei, but both names are currently in use, contrary to a fundamental tenet of biological nomenclature, that there can be only one correct name for a taxon at a given position and rank. It is thus imperative that a binding decision is made on the question of whether H. greenii and H. greenei are confusable. Other epithets ruled as confusable, such as heteropodus vs. heteropus and macrocarpon vs. macrocarpum given in Art. 53 *Ex. 11 (a voted example), have the same derivation. In contrast, Art. 53 *Ex. 12, also a voted example, rules that in Senecio, the similar epithets napaeifolius and napifolius, derived from Napaea L. and Brassica napus L., respectively, are not considered confusable. If the honouring of a person is a value to be appropriately considered and retained if possible, then it is relevant that Greene, in choosing Hieracium traillii to replace H. greenii, chose an epithet that honours Traill Green, the same person honoured by the epithet he proposed to replace. The names Hieracium greenii and H. traillii are homotypic and both are in current use in standard botanical literature. To resolve this, we are requesting a binding decision as to whether the names H. greenii and H. greenei are sufficiently alike to be confused and thus should be treated as homonyms. I am grateful to Wes Knapp and Kanchi Gandhi, as well as editors John McNeill and John Wiersema of Taxon for valuable advice and for reviewing the manuscript and providing improving edits.