Eupatorium sessilifolium |
Eupatorium album |
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upland boneset, upland thoroughwort |
white thoroughwort |
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Habit | Perennials, 50–100+ cm. | Perennials, 40–100+ cm. | ||||||||
Stems | (from short caudices or rhizomes) single, sparsely branched distally, 5–10+ dm, glabrous or glabrate proximally, puberulent distally (among heads). |
(from short caudices or stout rhizomes) single, sparsely branched distally, pubescent throughout. |
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Leaves | usually opposite (distal sometimes alternate); simple, sessile; blades pinnately nerved, lanceolate to oblong, 70–150+ × 10–30 mm (lengths mostly 2–5 times widths), bases truncate to somewhat rounded, margins serrate, apices narrowly acute to acuminate, faces glabrate (scattered, fine hairs), 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 3–3.5 mm. |
(4–)5; corollas 4–4.5 mm. |
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Phyllaries | 10–15 in 2–3 series, elliptic to oblong, 2–5 × 0.5–1.5 mm, apices rounded to acute (not mucronate), abaxial faces villous to 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 | 2–3 mm; pappi of 30–40 bristles 3–4 mm. |
2.5–3.5 mm; pappi of 40–50 bristles 3.5–4.5 mm. |
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2n | = 20, 30. |
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Eupatorium sessilifolium |
Eupatorium album |
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Phenology | Flowering Jul–Sep. | |||||||||
Habitat | Dry, open, edges of mesic woods | |||||||||
Elevation | 20–300+ m (100–1000+ ft) | |||||||||
Distribution |
AL; AR; CT; DE; GA; IA; IL; IN; KS; KY; MA; MD; MI; MN; MO; MS; NC; NH; NJ; NY; OH; PA; RI; SC; TN; VA; VT; WI; WV
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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 | 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. 474. | FNA vol. 21, p. 465. | ||||||||
Parent taxa | Asteraceae > tribe Eupatorieae > Eupatorium | Asteraceae > tribe Eupatorieae > Eupatorium | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Name authority | Linnaeus: Sp. Pl. 2: 837. (1753) | Linnaeus: Mant. Pl., 111. (1767): Syst. Nat. ed. 12, 2: 536. (1767) | ||||||||
Web links |