Eupatorium mohrii |
Eupatorium album |
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Mohr's thoroughwort |
white thoroughwort |
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Habit | Perennials, 30–100+ cm. | Perennials, 40–100+ cm. | ||||||||
Stems | (from tuberous rhizomes) multiple, densely branched distally, puberulent throughout. |
(from short caudices or stout rhizomes) single, sparsely branched distally, pubescent throughout. |
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Leaves | 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 (distal sometimes alternate); sessile; blades ± 3-nerved or pinnately nerved, elliptic to oblanceolate, 30–120 × 10–40 mm (lengths mostly 3–4 times widths), bases narrowly cuneate (sometimes oblique), margins subentire, serrate, or serrulate, apices rounded to acute, faces setulose (denser on midribs and veinlets) to glabrate, usually gland-dotted. |
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Florets | 5; corollas 2–4 mm. |
(4–)5; corollas 4–4.5 mm. |
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Phyllaries | 7–10 in 1–2 series, oblanceolate, 1–3 × 0.2–0.5 mm, apices rounded, abaxial faces puberulent, gland-dotted. |
9–15 in 2–4 series, linear, 1.5–9 × 0.6–1 mm, apices acuminate to attenuate, sometimes mucronate, abaxial faces pubescent throughout, gland-dotted. |
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Heads | in corymbiform arrays. |
in corymbiform arrays. |
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Cypselae | 1–2 mm; pappi of 20–30 bristles 2.5–3 mm. |
2.5–3.5 mm; pappi of 40–50 bristles 3.5–4.5 mm. |
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2n | = 20, 30, 40. |
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Eupatorium mohrii |
Eupatorium album |
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Phenology | Flowering Jul–Sep. | |||||||||
Habitat | Moist, low ground, margins of ponds, sandy soils | |||||||||
Elevation | 10–100+ m (0–300+ ft) | |||||||||
Distribution |
AL; FL; GA; LA; MS; NC; SC; TX; VA
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AL; CT; DC; DE; FL; GA; KY; LA; MD; MS; NC; NJ; NY; OH; PA; SC; TN; VA; WV
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Discussion | 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.) |
Varieties 3 (3 in the flora). Eupatorium album is represented by widespread diploid populations and by polyploid, apomictic populations, segregated as varieties, that may have arisen by hybridization with other species. Molecular data suggest that var. vaseyi arose via hybridization between var. album and E. sessilifolium. They also suggest that E. album var. subvenosum arose from hybridization between E. album var. album and E. serotinum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 21, p. 470. | FNA vol. 21, p. 465. | ||||||||
Parent taxa | Asteraceae > tribe Eupatorieae > Eupatorium | Asteraceae > tribe Eupatorieae > Eupatorium | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | E. recurvans | |||||||||
Name authority | Greene: Contr. U.S. Natl. Herb. 6: 762, plate 11. (1901) | Linnaeus: Mant. Pl., 111. (1767): Syst. Nat. ed. 12, 2: 536. (1767) | ||||||||
Web links |