Eupatorium album |
Eupatorium anomalum |
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white thoroughwort |
Florida thoroughwort |
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Habit | Perennials, 40–100+ cm. | Perennials, 80–150+ cm. | ||||||||
Stems | (from short caudices or stout rhizomes) single, sparsely branched distally, pubescent throughout. |
(from tuberous rhizomes) single, densely branched distally (shoots often develop from lateral buds), puberulent throughout (denser distally). |
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Leaves | 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. |
usually opposite (distal sometimes alternate); sessile or subsessile; blades 3-nerved distal to bases, elliptic to oblong, 15–50 × (5–)10–20 mm, bases cuneate, margins entire or serrate (unevenly toothed), apices rounded to acute, faces puberulent (abaxial) or glabrate (adaxial), gland-dotted (both). |
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Florets | (4–)5; corollas 4–4.5 mm. |
5; corollas 3–3.5 mm. |
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Phyllaries | 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. |
8–12 in 2–3 series, oblong to lanceolate, 2.5–5 × 0.5–0.7 mm, apices rounded to acute, abaxial faces puberulent throughout. |
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Heads | in corymbiform arrays. |
in corymbiform arrays. |
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Cypselae | 2.5–3.5 mm; pappi of 40–50 bristles 3.5–4.5 mm. |
1.8–3 mm; pappi of 20–35 bristles 3.5–4.5 mm. |
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2n | = 20, 30, 40. |
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Eupatorium album |
Eupatorium anomalum |
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Phenology | Flowering Jul–Aug. | |||||||||
Habitat | Wet, low ground, flatwoods | |||||||||
Elevation | 10–100 m (0–300 ft) | |||||||||
Distribution |
AL; CT; DC; DE; FL; GA; KY; LA; MD; MS; NC; NJ; NY; OH; PA; SC; TN; VA; WV
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AL; FL; GA; NC; SC |
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Discussion | 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.) |
Of conservation concern. Eupatorium anomalum has been proposed to be intermediate in morphology between E. rotundifolium and E. mohrii and, possibly, a hybrid derivative of that pairing. Molecular data suggest that its derivation is from hybridization between E. serotinum and E. mohrii. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 21, p. 465. | FNA vol. 21, p. 466. | ||||||||
Parent taxa | Asteraceae > tribe Eupatorieae > Eupatorium | Asteraceae > tribe Eupatorieae > Eupatorium | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Name authority | Linnaeus: Mant. Pl., 111. (1767): Syst. Nat. ed. 12, 2: 536. (1767) | Nash: Bull. Torrey Bot. Club 23: 106. (1896) | ||||||||
Web links |