Nuttall, Trans. Amer. Philos. Soc., n. s. 7: 367. 1841.
Annuals or perennials
, 30—200 cm (taprooted).
decumbent to erect, glabrous, hirsute, or puberulent.
mostly cauline; mostly alternate; petioles 1—7 cm; blades deltate-ovate, lance-ovate, or ovate, 2.5—14 × 1.8—13 cm, bases cordate to truncate or broadly cuneate, margins subentire to serrate, abaxial faces glabrate to hispid, not gland-dotted.
hemispheric, 10—22 mm diam.
20—30, lanceolate, 8—17 × 1—3 mm, apices acute to long-attenuate, abaxial faces glabrous or ± hispid, not gland-dotted.
7.5—8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded).
11—20; laminae 12—23 mm.
30+; corollas 4.5—5 mm, lobes usually reddish, sometimes yellow; anthers dark, appendages dark (style branches usually reddish, rarely yellow).
2.5—3.2 mm, glabrous or sparsely hairy;
of 2 lanceolate or lance-linear scales 1.2—2.5 mm.
Subspecies 5 (5 in the flora): United States (Atlantic and Gulf coasts).
C. B. Heiser (1956) placed 8 subspecies in
; he noted that alternative taxonomic treatments might recognize these in as many as three species, or expand the single species to include
. Later, Heiser et al. (1969) separated three of the subspecies as
. Isozyme data (R. P. Wain 1982, 1983; L. H. Rieseberg and M. F. Doyle 1989) show that all are closely related. Documented hybridization with
further complicates the situation. The treatment by Heiser et al. is followed here.
is adventive beyond the Atlantic and Gulf coasts of the United States.