Eupatorium mohrii |
Eupatorium semiserratum |
|
---|---|---|
Mohr's thoroughwort |
smallflower eupatorium, smallflower thoroughwort |
|
Habit | Perennials, 30–100+ cm. | Perennials, 40–100+ cm. |
Stems | (from tuberous rhizomes) multiple, densely branched distally, puberulent throughout. |
(from short rhizomes) single, densely branched distally, puberulent throughout. |
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, lateral buds dormant or producing 1 pair of leaves); simple, sessile or subsessile; blades ± 3-nerved distal to bases, elliptic to lance-elliptic, (30–)50–70 × 5–25 mm (lengths mostly 2–5 times widths), bases narrowly cuneate, margins usually serrate, apices acute, faces puberulent or villous, densely gland-dotted. |
Florets | 5; corollas 2–4 mm. |
5; corollas 2.5–3 mm. |
Phyllaries | 7–10 in 1–2 series, oblanceolate, 1–3 × 0.2–0.5 mm, apices rounded, abaxial faces puberulent, gland-dotted. |
7–10 in 2–3 series, elliptic, 1–3 × 0.5–1 mm, apices rounded to acute (not mucronate), abaxial faces puberulent, gland-dotted. |
Heads | in corymbiform arrays. |
in corymbiform arrays. |
Cypselae | 1–2 mm; pappi of 20–30 bristles 2.5–3 mm. |
1.5–2 mm; pappi of 30–40 bristles 2.5–3 mm. |
2n | = 20, 30, 40. |
= 20. |
Eupatorium mohrii |
Eupatorium semiserratum |
|
Phenology | Flowering Jul–Sep. | Flowering Aug–Sep. |
Habitat | Moist, low ground, margins of ponds, sandy soils | Moist to boggy, sandy, peaty soils, margins of pine flatwoods, gum swamps, bayheads, disturbed sites, roadsides |
Elevation | 10–100+ m (0–300+ ft) | 10–100+ m (0–300+ ft) |
Distribution |
AL; FL; GA; LA; MS; NC; SC; TX; VA
|
AL; AR; FL; GA; LA; MS; NC; SC; TN
|
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.) |
Eupatorium semiserratum has been included within E. glaucescens (E. cuneifolium); it is distinguished by its consistently smaller heads and stems that branch only within the capitulescences. It differs from the similar and sometimes sympatric E. lancifolium by its smaller heads, leaves 3-nerved distal to bases (rather than at bases), as well as preference for wetter habitats. It has been proposed that E. rotundifolium var. scabridum (E. pubescens) represents hybrids between E. semiserratum and E. rotundifolium; it also apparently hybridizes with E. hyssopifolium. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 21, p. 470. | FNA vol. 21, p. 473. |
Parent taxa | Asteraceae > tribe Eupatorieae > Eupatorium | Asteraceae > tribe Eupatorieae > Eupatorium |
Sibling taxa | ||
Synonyms | E. recurvans | E. cuneifolium var. semiserratum |
Name authority | Greene: Contr. U.S. Natl. Herb. 6: 762, plate 11. (1901) | de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 177. (1836) |
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