2. Fraxinus biltmoreana Beadle (Biltmore ash)

F. americana L. ssp. biltmoreana (Beadle) A.E. Murray

F. americana var. biltmoreana (Beadle) J. Wright ex Fernald

Map 2096

Plants trees to 35 m tall with an oval crown, dioecious or incompletely dioecious. Twigs circular in cross-section, unwinged, moderately to densely pubescent with short, felty or somewhat matted hairs, not glaucous, gray to brown with relatively inconspicuous, paler, circular to elongate lenticels, the leaf scars oblong-obovate to depressed-obovate, shallowly notched to nearly truncate on the apical side, the associated axillary buds brown, not strongly sunken into the twig. Terminal buds 4–6 mm long, broadly ovoid to broadly conic, wider than long, rounded to bluntly pointed at the tip, dark reddish brown, hairy, often also with scattered, minute, peltate scales (sometimes occurring in patches), with 3 or 4 pairs of scales, the outermost pair relatively short and tightly appressed. Leaves (5–)9–40 cm long, the petiole moderately to densely short-hairy. Leaflets mostly (5)7–9, 2–20 cm long, 1–9 cm wide, variable in shape but mostly lanceolate to ovate or elliptic, rounded or angled to the sometimes slightly apically winged stalk (this mostly 8–18 mm long on the terminal leaflet and 3–15 mm long on lateral leaflets), relatively thin to slightly leathery, the upper surface glabrous or less commonly sparsely short-hairy, dull to slightly shiny, the undersurface glabrous or sparsely to moderately short-hairy, usually whitened, the margins entire or with blunt teeth. Calyces present, persistent at fruiting, 0.5–1.5 mm long. Fruits 35–54 mm long, the slender stalk 5–10 mm long, the body (7–)11–15 mm long, 2–4 mm wide, slender, narrowly oblong in outline, not flattened, the wing 6–8 mm wide, narrowly oblanceolate to narrowly oblong-lanceolate, more or less rounded at the tip, less commonly with a small notch or bluntly pointed, extending less than 1/3 of the way along each side of the body. 2n=138. April–May.

Uncommon, known thus far only from Dunklin County (eastern U.S. west to Illinois, Missouri, Arkansas, and Louisiana). Swamps and bottomland forests.

Fraxinus biltmoreana has been included in synonymy under F. americana by many botanists (Hardin and Beckmann, 1982; Gleason and Cronquist, 1991) or treated as a variety of that species (Fernald, 1950; Steyermark, 1963). G. N. Miller (1955) and Santamour (1962) discussed morphological distinctions between members of the F. americana polyploid complex. Nesom (2010a) expanded on these earlier studies and provided a more incisive morphological analysis. Fraxinus biltmoreana is a hexaploid (2n=138) member of the complex and, according to Nesom, is characterized by the pubescence on its twigs, petioles, and leaf rachises, and also by averaging the largest fruits in the complex. G. N. Miller (1955) suggested that the Biltmore ash originated through past hybridization between F. americana and F. pennsylvanica (an origin that also has been suggested for F. profunda). Black-Schaeffer and Beckmann’s (1989) study of secondary biochemistry in the leaves of ash species showed the presence of flavonoid compounds in F. biltmoreana that were more or less additive between those found in F. americana and F. pennsylvanica. Wallander’s (2008) molecular analysis of the genus also did not contradict this interpretation. If the parentage of F. biltmoreana should become confirmed as the result of a cross between a diploid F. pennsylvanica parent and a tetraploid member of the F. americana complex, then that tetraploid likely represents the taxon treated here as F. smallii.