Eupatorium petaloideum


Bull. Torrey Bot. Club 24: 492. 1897.

Common names: Showy white thoroughwort
Synonyms: Eupatorium album var. petaloideum (Britton) R. K. Godfrey ex D. B. Ward
Treatment appears in FNA Volume 21. Treatment on page 471. Mentioned on page 463.

Perennials, 30–70 cm. Stems (from short, stout rhizomes) single, branched distally, puberulent. Leaves usually opposite (distal sometimes alternate); sessile; blades pinnately nerved, elliptic to ovate, 20–80 × 10–30 mm, bases cuneate, margins serrate to crenate-serrate, apices rounded to acute, faces sparsely villous (abaxial), glabrate (adaxial), little, if at all, gland-dotted. Heads in corymbiform arrays. Phyllaries 9–15 in 2–4 series, linear, 4–10 × 0.6–1 mm, apices (white) acuminate to attenuate, strongly mucronate, abaxial faces glabrous, not gland-dotted. Florets (4–)5; corollas 3–3.5 mm. Cypselae 2.5–3 mm; pappi of 40–50 bristles 3.5–4 mm. 2n = 20.

Phenology: Flowering Jul–Sep.
Habitat: Upland scrub oak and longleaf pinewoods, fine textured, loamy soils
Elevation: 20–100+ m


Eupatorium petaloideum is commonly combined with E. album; it has recently been separated as a distinct variety. V. I. Sullivan (1972) found the two taxa to be distinct chemically and to occupy different habitats. In both, the involucral bracts are white and long-acuminate or mucronate; those of E. petaloideum are almost entirely devoid of any pubescence including glands and those of E. album have both simple and glandular hairs.

Selected References


Lower Taxa

... more about "Eupatorium petaloideum"
Kunsiri Chaw Siripun +  and Edward E. Schilling +
Britton +
Showy white thoroughwort +
Ala. +, Fla. +, Ga. +  and Miss. +
20–100+ m +
Upland scrub oak and longleaf pinewoods, fine textured, loamy soils +
Flowering Jul–Sep. +
Bull. Torrey Bot. Club +
Eupatorium album var. petaloideum +
Eupatorium petaloideum +
Eupatorium +
species +