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ragged thoroughwort, rough boneset

Habit Perennials, 30–100+ cm.
Stems

(from short rhizomes) single, sparsely branched distally, densely puberulent to pilose throughout.

Leaves

usually opposite (distal sometimes alternate); simple, sessile or subsessile;

blades ± 3-nerved (distal to bases), elliptic, lanceolate, or lance-ovate, 30–90 × 20–45 mm (lengths mostly 2–2.5 times widths), bases rounded to rounded-cuneate, margins unevenly serrate, apices acute to attenuate, faces puberulent, gland-dotted.

Florets

5;

corollas 3.5–4 mm.

Phyllaries

7–10 in 2–3 series, oblong to lance-oblong, 2–7 × 1–1.5 mm, apices (sometimes whitish) acuminate to acute, mucronate, abaxial faces puberulent, gland-dotted.

Heads

in corymbiform arrays.

Cypselae

3–4 mm;

pappi of 30–50 bristles 4–5 mm.

2n

= 20, 30, 40.

Eupatorium pilosum

Phenology Flowering Jul–Sep.
Habitat Moist, low ground, margins of ponds, sandy soils, savannas, ditches
Elevation 20–100+ m (100–300+ ft)
Distribution
from FNA
AL; CT; DE; FL; GA; KY; LA; MA; MD; MS; NC; NJ; NY; PA; RI; SC; TN; VA; WV
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Discussion

Eupatorium pilosum has been most commonly treated as a variety of E. rotundifolium; it is distinct morphologically by its leaves, which are narrower and 3-nerved distal to bases, rather than 3-nerved from bases. Distal leaves of E. pilosum tend to differ from the proximal by being alternate with entire margins.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 21, p. 471.
Parent taxa Asteraceae > tribe Eupatorieae > Eupatorium
Sibling taxa
E. album, E. altissimum, E. anomalum, E. cannabinum, E. capillifolium, E. compositifolium, E. godfreyanum, E. hyssopifolium, E. lancifolium, E. leptophyllum, E. leucolepis, E. linearifolium, E. mikanioides, E. mohrii, E. perfoliatum, E. petaloideum, E. resinosum, E. rotundifolium, E. semiserratum, E. serotinum, E. sessilifolium, E. ×cordigerum, E. ×pinnatifidum
Synonyms E. rotundifolium var. saundersii, E. verbenifolium
Name authority Walter: Fl. Carol., 199. (1788)
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