Eupatorium rotundifolium
Eupatorium perfoliatum
round-leaf boneset, round-leaf thoroughwort, roundleaf eupatorium
boneset thoroughwort, Chapman's thoroughwort, common boneset, eupatoire perfoliée
(from short rhizomes) single, sparsely branched distally, puberulent.
(from short caudices) single, sparsely branched distally, puberulent throughout.
usually opposite (distal sometimes alternate, lateral buds dormant or producing 1 pair of leaves);
sessile or subsessile;
blades ± 3-nerved, usually ± deltate to orbiculate, sometimes ovate, 15–50(–70) × 15–40(–60) mm (lengths mostly 1–2 times widths), bases broadly rounded to truncate, margins crenate to serrate, apices acute, faces puberulent to villous, gland-dotted.
usually opposite (sometimes whorled);
sessile;
blades pinnately nerved, oblong (tapering toward apices), 50–150+ × 15–40 mm, bases connate-perfoliate, margins serrate, apices acute, faces pilose, gland-dotted (abaxial), glabrate, not gland-dotted (adaxial).
5;
corollas 3–4 mm.
7–11;
corollas 2.5–3 mm.
8–10 in 2–3 series, elliptic to oblanceolate, 2–6 × 0.5–1.5 mm, apices acute, abaxial faces puberulent, gland-dotted.
7–10 in 1–2 series, oblong, 2–4.5 × 0.6–1 mm, apices (whitish) acute to acuminate, abaxial faces villous or puberulent, gland-dotted.
in corymbiform arrays.
in corymbiform arrays.
2–3 mm;
pappi of 30–40 bristles 3.5–4 mm.
1.5–2 mm;
pappi of 20–30 bristles 3–3.5 mm.
= 20.
Eupatorium rotundifolium
Eupatorium perfoliatum
Varieties 3 (3 in the flora).
Eupatorium rotundifolium is one of the more variable species of the genus; its apparent propensity to hybridize with other species has led it to be described as a compilospecies and has complicated its delimitation. Hybrids with E. perfoliatum and E. sessilifolium are sufficiently distinctive to be treated here as distinctive entities (E. ×cordigerum and E. godfreyanum, respectively), and the varieties ovatum and scabridum have also been proposed to be of hybrid origin. The boundaries between varieties are indistinct and individual specimens may be difficult to place with confidence.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Eupatorium perfoliatum is both distinctive, with its perfoliate leaf bases, and extraordinarily widespread. Hybrids between E. perfoliatum and other species of Eupatorium have been reported. The name E. resinosum var. kentuckiense Fernald is based on hybrids between E. perfoliatum and E. serotinum (= E. ×truncatum Muhlenberg ex Willdenow). Eupatorium perfoliatum var. colpophilum refers to populations characterized by narrower, more leathery leaves found in the extreme northeastern portion of the range.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaf blades 3-nerved from bases, bases subtruncate to broadly cuneate, margins crenate | var. rotundifolium |
1. Leaf blades 3-nerved distal to bases, bases broadly cuneate to cuneate, margins serrate | → 2 |
2. Leaf blades 30–70 × 30–60 mm, broadest nearmiddles | var. ovatum |
2. Leaf blades 20–50 × 15–30 mm, broadest nearbases | var. scabridum |
Go Botany
LA Plants
MD Biodiversity
MO Plants
WildflowerSearch
iNaturalist
USDA Plants Database
IL Wildflowers
KS Wildflowers
MI Flora
MN Wildflowers
