Eupatorium mohrii
Eupatorium altissimum
Mohr's thoroughwort
tall boneset, tall joepyeweed, tall thoroughwort
(from tuberous rhizomes) multiple, densely branched distally, puberulent throughout.
(from short caudices or stout rhizomes) single, sparsely branched distally, pubescent throughout (nodes sometimes with galls).
usually opposite (distal sometimes alternate);
sessile or subsessile;
blades 3-nerved distal to bases, oblanceolate, 20–80 × 5–10(–20) mm, bases cuneate, margins serrate proximally, entire distally, apices acute, faces puberulent (abaxial), glabrous or glabrate (adaxial), gland-dotted.
usually opposite (nodes often appearing leafy, lateral buds producing 2+ pairs of leaves);
sessile or subsessile;
blades strongly 3-nerved from bases, lance-elliptic to oblanceolate, 50–120 × 5–20 mm, bases ± cuneate, margins entire proximally, serrate distally, apices acuminate, faces puberulent or villous, gland-dotted.
5;
corollas 2–4 mm.
5;
corollas 3–3.5 mm.
7–10 in 1–2 series, oblanceolate, 1–3 × 0.2–0.5 mm, apices rounded, abaxial faces puberulent, gland-dotted.
8–10 in 2–3 series, oblong, 1–4 × 0.5–1.5 mm, (bases tapered) apices rounded to acute (not mucronate), abaxial faces pubescent throughout.
in corymbiform arrays.
in corymbiform arrays.
1–2 mm;
pappi of 20–30 bristles 2.5–3 mm.
2–3 mm;
pappi of 30–40 bristles 3.5–4 mm.
= 20, 30, 40.
= 20, 30, 40.
Eupatorium mohrii
Eupatorium altissimum
As treated here, Eupatorium mohrii includes both sexual diploid (sometimes segregated as E. recurvans) and apomictic polyploid populations that are suggested by molecular data to be autoploids. Eupatorium saltuense refers to hybrids shown by molecular data to involve E. mohrii and E. serotinum. Molecular data also document frequent hybridization with E. rotundifolium.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Eupatorium altissimum occurs in sexual diploid populations in the Ozark region of Missouri and Arkansas, and as apomictic polyploids elsewhere throughout its range. It occurs almost exclusively on limestone soils, where it is often accompanied by (and sometimes misidentified as) Brickellia eupatorioides, which has 10-ribbed cypselae and plumose pappus bristles. Eupatorium altissimum hybridizes with E. serotinum.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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