Eupatorium album |
Eupatorium linearifolium |
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white thoroughwort |
waxy thoroughwort |
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Habit | Perennials, 40–100+ cm. | Perennials, 30–100+ cm. | ||||||||
Stems | (from short caudices or stout rhizomes) single, sparsely branched distally, pubescent throughout. |
(from short caudices) single or multiple, branched at or near bases, pubescent 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 or subsessile; blades 3-nerved distal to bases, oblong to lance-oblong, 20–45 × 5–10 mm, bases cuneate, margins entire or serrate (teeth mostly proximal), apices acute, faces finely puberulent, gland-dotted. |
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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. |
8–10 in 1–2 series, lanceolate (tapering toward apices), 2–5 × 0.5–1 mm, apices rounded 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. |
2.5–3 mm; pappi of 30–40 bristles 3–5 mm. |
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2n | = 20, 30, 40. |
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Eupatorium album |
Eupatorium linearifolium |
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Phenology | Flowering Jul–Sep. | |||||||||
Habitat | Dry, sandy soils, pine and oak woods, old fields | |||||||||
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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AL; DE; FL; GA; MS; NC; SC; TX
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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.) |
Plants treated here as Eupatorium linearifolium were long treated under the name E. cuneifolium; the latter name was superfluous when published (K. N. Gandhi and R. D. Thomas 1991). Because there appears to be a continuous range of variation between diploids that were referred to by V. I. Sullivan (1972) as E. cuneifolium and the series of putative hybrids (with E. hyssopifolium suggested as the other parent) that she called E. linearifolium, these are combined here. The tendency for the plants to branch at or near the bases is distinctive within Eupatorium. (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. 470. | ||||||||
Parent taxa | Asteraceae > tribe Eupatorieae > Eupatorium | Asteraceae > tribe Eupatorieae > Eupatorium | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | E. cuneifolium, E. glaucescens, E. tortifolium | |||||||||
Name authority | Linnaeus: Mant. Pl., 111. (1767): Syst. Nat. ed. 12, 2: 536. (1767) | Walter: Fl. Carol., 199. (1788) | ||||||||
Web links |