Eutrochium dubium

(Willdenow ex Poiret) E. E. Lamont

Sida 21: 901. 2004.

Common names: Coastal plain joepyeweed joepye thoroughwort
Endemic
Basionym: Eupatorium dubium Willdenow ex Poiret in J. Lamarck et al., Encycl., suppl. 2: 606. 1812
Synonyms: Eupatoriadelphus dubius (Willdenow ex Poiret) R. M. King & H. Robinson Eupatorium americanum Hill Eupatorium ternifolium Elliott
Treatment appears in FNA Volume 21. Treatment on page 475.

Plants 40–120 (–170) cm. Stems usually purple-spotted, sometimes uniformly purple, solid, glabrous proximally, glandular-puberulent distally. Leaves mostly in 3s–4s; petioles 7–25 mm, glabrous; blades usually ± 3-nerved, rarely pinnately veined, deltate-ovate or ovate to lanceovate, 5–16 × 2–8 cm, relatively thick and firm (often rugose), bases usually abruptly contracted to petioles, margins coarsely serrate, abaxial faces densely glanddotted and sparingly hirsute (at least on midribs and main veins), adaxial faces scabrous, glabrescent. Heads usually in ± convex, sometimes flat-topped, corymbiform arrays. Involucres often purplish, 6.5–9 × 2.5–5 mm. Phyllaries glabrous or sparsely hairy. Florets (4–) 5–9 (–10); corollas usually dark purple, rarely pinkish or white, 4.5–7 mm. Cypselae 3–4.5 mm. 2n = 20.


Phenology: Flowering late summer–early fall.
Habitat: Moist habitats, in sandy or gravelly, acid soils, open sun or partial shade
Elevation: 0–50+ m

Distribution

V21-1191-distribution-map.gif

N.S., Conn., Del., Maine, Md., Mass., N.H., N.J., N.Y., N.C., Pa., R.I., S.C., Vt., Va.

Discussion

Eutrochium dubium is restricted to the coastal plain, and inland along major river systems, of eastern North America. Identification of E. dubium has been difficult for field botanists, as evidenced by misidentified herbarium specimens. The most prominent character distinguishing E. dubium from its relatives (especially E. maculatum) is the 3-nerved leaf venation: the proximalmost pair of lateral veins are more prominent and more prolonged than the others. This character is best observed on abaxial leaf faces.

Selected References

None.

Lower Taxa

None.

"fine" is not a number.

... more about "Eutrochium dubium"
not tailed +, truncate +, rounded +  and obtuse +
scarious +
usually ovate +  and lanceolate +
usually terete +  and clavate +
corymbiform +  and compound +
indeterminate +  and determinate +
Eric E. Lamont +
(Willdenow ex Poiret) E. E. Lamont +
puberulent +
decurrent +
enlarged +
Eupatorium dubium +
veined +  and 3-nerved +
5 cm50 mm <br />0.05 m <br /> (16 cm160 mm <br />0.16 m <br />) +
dissected +, lobed +, toothed +  and entire +
ovate;lanceovate +
thick;2cm;8cm +
papillate +  and rugose +
(4-)5-angled;10-ribbed +
less filiform;clavate +
Coastal plain joepyeweed +  and joepye thoroughwort +
white +, pinkish +  and dark purple +
0.45 cm4.5 mm <br />0.0045 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
scabrellous +
prismatic +
fertile +  and bisexual +
N.S. +, Conn. +, Del. +, Maine +, Md. +, Mass. +, N.H. +, N.J. +, N.Y. +, N.C. +, Pa. +, R.I. +, S.C. +, Vt. +  and Va. +
0–50+ m +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Moist habitats, in sandy or gravelly, acid soils, open sun or partial shade +
in usually determinate , rarely indeterminate , arrays +  and singly +
indeterminate +
each +  and sessile +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
0.65 cm6.5 mm <br />0.0065 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
opposite +  and whorled +
ovate +  and deltate +
2-carpellate +
persistent +
0.7 cm7 mm <br />0.007 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
Flowering late summer–early fall. +
hairy +  and glabrous +
10 +  and 22 +
bearing subulate enations +, hairy +  and bristly +
convex;flat +
exalbuminous +
purple-spotted +
appendaged +  and truncate +
hirsutulous +
papillate +
Eupatoriadelphus dubius +, Eupatorium americanum +  and Eupatorium ternifolium +
Eutrochium dubium +
Eutrochium +
species +
30 cm300 mm <br />0.3 m <br /> (350 cm3,500 mm <br />3.5 m <br />) +