Eupatorium ×cordigerum

(Fernald) Fernald

Rhodora 47: 192. 1945.

Basionym: Eupatorium rotundifolium var. cordigerum Fernald Rhodora 45: 477. 1943
Treatment appears in FNA Volume 21. Treatment on page 467. Mentioned on page 463, 464, 472.

Perennials, 40–100+ cm. Stems (from short rhizomes) single, branched distally, densely pilose. Leaves usually opposite (distal sometimes alternate); sessile; blades ± 3-nerved or pinnately nerved, ovate, 3–9.8 × 1.6–5.7 cm, bases clasping or narrowly perfoliate, margins serrate, apices acute, faces (rugose) sparsely pilose (adaxial) or densely pilose (abaxial) and densely glanddotted. Heads in corymbiform arrays. Phyllaries 7–10 in 2–3 series, 4–12 × 1–4 mm, apices (usually white) acuminate to acute, abaxial faces pilose, glanddotted. Florets 5–8; corollas 2.5–3 mm. Cypselae 2–3 mm; pappi of 30–40 bristles 3.5–4.5 mm. 2n = 30, 40.


Phenology: Flowering Jul–Aug.
Habitat: Margins of woods, moist areas
Elevation: 10–100+ m

Distribution

V21-1165-distribution-map.gif

Ark., Miss., N.J., N.C., S.C., Va.

Discussion

Eupatorium ×cordigerum is an apomictic, polyploid hybrid of E. rotundifolium and E. perfoliatum that occurs in disturbed areas where those two species occur together. It is not uncommonly encountered; it is unclear how long it persists.

Selected References

None.

Lower Taxa

None.

"fine" is not a number.

... more about "Eupatorium ×cordigerum"
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 +
(Fernald) Fernald +
perfoliate +  and clasping +
puberulent +
decurrent +
enlarged +
Eupatorium rotundifolium var. cordigerum +
nerved +  and 3-nerved +
3 cm30 mm <br />0.03 m <br /> (9.8 cm98 mm <br />0.098 m <br />) +
dissected +, lobed +, toothed +  and entire +
1.6cm;5.7cm +
papillate +  and rugose +
(4-)5-angled;10-ribbed +
filiform +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
pinkish +  and white +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
prismatic +
fertile +  and bisexual +
Ark. +, Miss. +, N.J. +, N.C. +, S.C. +  and Va. +
10–100+ m +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Margins of woods, moist areas +
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 +
2-carpellate +
persistent +
Flowering Jul–Aug. +
nerved +  and 2-3-nerved +
0.4 cm4 mm <br />0.004 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
7 +  and 10 +
0.1 cm1 mm <br />0.001 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
bearing subulate enations +, hairy +  and bristly +
convex;flat +
exalbuminous +
appendaged +  and truncate +
hirsutulous +
papillate +
Compositae +
Eupatorium ×cordigerum +
Eupatorium +
species +
campanulate +
toothed +  and entire +
40 cm400 mm <br />0.4 m <br /> (100 cm1,000 mm <br />1 m <br />) +
vine +, shrub +  and subshrub +