Eupatorium album |
Eupatorium resinosum |
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white thoroughwort |
pine barren thoroughwort |
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Habit | Perennials, 40–100+ cm. | Perennials, 40–100+ cm. | ||||||||
Stems | (from short caudices or stout rhizomes) single, sparsely branched distally, pubescent throughout. |
(from short rhizomes) single, branched distally (among heads), puberulent throughout. |
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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; blades pinnately nerved, narrowly elliptic, 40–100+ × 5–20 mm, bases cuneate (not perfoliate), margins serrate, apices acute to acuminate, faces puberulent, gland-dotted. |
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Florets | (4–)5; corollas 4–4.5 mm. |
9–14; 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. |
10–12 in 2–3 series, elliptic to oblong, 1.5–4 × 0.8–1 mm, apices broadly acute to acute, abaxial faces puberulent, gland-dotted. |
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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. |
2–3 mm; pappi of 20–30 bristles 3–3.5 mm. |
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2n | = 20. |
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Eupatorium album |
Eupatorium resinosum |
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Phenology | Flowering Aug–Sep. | |||||||||
Habitat | Moist, low ground, pocosins, bogs, cutover woodlands, pine barrens, acid soils | |||||||||
Elevation | 20–100+ m (100–300+ 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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NC; NJ; 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.) |
Eupatorium resinosum is in the Center for Plant Conservation’s National Collection of Endangered Plants. (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. 472. | ||||||||
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) | Torrey ex de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 176. (1836) | ||||||||
Web links |