Eupatorium petaloideum

Britton

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

Common names: Showy white thoroughwort
Endemic
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, glanddotted. 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 glanddotted. 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

Discussion

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

None.

Lower Taxa

None.

"fine" is not a number.

... more about "Eupatorium petaloideum"
not tailed +, truncate +, rounded +  and obtuse +
scarious +
usually ovate +  and lanceolate +
usually terete +  and clavate +
diffuse +  and dense +
indeterminate +  and determinate +
Kunsiri Chaw Siripun +  and Edward E. Schilling +
Britton +
puberulent +
cuneate +
enlarged +
2 cm20 mm <br />0.02 m <br /> (8 cm80 mm <br />0.08 m <br />) +
dissected +, lobed +, toothed +  and entire +
elliptic;ovate +
10mm;30mm +
papillate +  and rugose +
(4-)5-angled;10-ribbed +
filiform +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
Showy white thoroughwort +
pinkish +  and white +
0.3 cm3 mm <br />0.003 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
prismatic +
fertile +  and bisexual +
Ala. +, Fla. +, Ga. +  and Miss. +
20–100+ m +
glabrate +  and villous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Upland scrub oak and longleaf pinewoods, fine textured, loamy soils +
in usually determinate , rarely indeterminate , arrays +  and singly +
indeterminate +
each +  and sessile +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
obconic;ellipsoid +
triangular +
serrate to crenate-serrate +
2-carpellate +
persistent +
Flowering Jul–Sep. +
nerved +  and 2-3-nerved +
0.4 cm4 mm <br />0.004 m <br /> (1 cm10 mm <br />0.01 m <br />) +
9 +  and 15 +
0.06 cm0.6 mm <br />6.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
Bull. Torrey Bot. Club +
bearing subulate enations +, hairy +  and bristly +
convex;flat +
exalbuminous +
appendaged +  and truncate +
hirsutulous +
papillate +
Eupatorium album var. petaloideum +
Eupatorium petaloideum +
Eupatorium +
species +
campanulate +
toothed +  and entire +
30 cm300 mm <br />0.3 m <br /> (70 cm700 mm <br />0.7 m <br />) +
vine +, shrub +  and subshrub +