Eupatorium semiserratum

de Candolle

in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 177. 1836.

Common names: Smallflower thoroughwort
Endemic
Synonyms: Eupatorium cuneifolium var. semiserratum (de Candolle) Fernald & Griscom
Treatment appears in FNA Volume 21. Treatment on page 473. Mentioned on page 464, 469.

Perennials, 40–100+ cm. Stems (from short rhizomes) single, densely branched distally, puberulent throughout. Leaves 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. Heads in corymbiform arrays. Phyllaries 7–10 in 2–3 series, elliptic, 1–3 × 0.5–1 mm, apices rounded to acute (not mucronate), abaxial faces puberulent, gland-dotted. Florets 5; corollas 2.5–3 mm. Cypselae 1.5–2 mm; pappi of 30–40 bristles 2.5–3 mm. 2n = 20.


Phenology: Flowering Aug–Sep.
Habitat: Moist to boggy, sandy, peaty soils, margins of pine flatwoods, gum swamps, bayheads, disturbed sites, roadsides
Elevation: 10–100+ m

Distribution

V21-1187-distribution-map.gif

Ala., Ark., Fla., Ga., La., Miss., N.C., S.C., Tenn.

Discussion

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.

Selected References

None.

Lower Taxa

None.
... more about "Eupatorium semiserratum"
Kunsiri Chaw Siripun +  and Edward E. Schilling +
de Candolle +
Smallflower thoroughwort +
Ala. +, Ark. +, Fla. +, Ga. +, La. +, Miss. +, N.C. +, S.C. +  and Tenn. +
10–100+ m +
Moist to boggy, sandy, peaty soils, margins of pine flatwoods, gum swamps, bayheads, disturbed sites, roadsides +
Flowering Aug–Sep. +
in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. +
Eupatorium cuneifolium var. semiserratum +
Eupatorium semiserratum +
Eupatorium +
species +