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Arkansas ironweed, great ironweed

giant ironweed, tall ironweed

Habit Plants 8–12(–20) dm. Plants 8–20(–30+) dm.
Stems

scabrellous to pilosulous, glabrescent.

puberulent, glabrescent.

Leaves

mostly cauline;

blades lance-linear, 6–14(–20) cm × 7–15(–25) mm, l/w = 7–10(–18), abaxially scabrellous (hairs awl-shaped), resin-gland-dotted, adaxially scaberulous, glabrescent, resin-gland-dotted.

mostly cauline;

blades ± lanceolate, 12–25+ cm × 20–60+ mm, l/w = (3.5–)4–7+, abaxially scabrellous (hairs awl-shaped), sometimes glabrescent, not or sparsely resin-gland-dotted, adaxially strigillose, glabrescent, not resin-gland-dotted.

Peduncles

2–5 cm.

1–12(–20+) mm.

Involucres

± hemispheric, 11–15 × 11–15 mm.

broadly campanulate to hemispheric, 4–5+ × 4–5 mm.

Florets

50–100+.

(9–)18–24(–30).

Phyllaries

(50–)60–70+ in 5–6 series, scabrellous (and resin-gland-dotted), margins ciliolate, the outer lance-ovate, 3–8+ mm, inner lanceolate, 12–15 mm, tips subulate to filiform.

30–40+ in 4–5 series, glabrate, margins ciliolate, the outer lance-ovate, 1–2 mm, inner oblong, 3.5–5 mm, tips acute or rounded-apiculate.

Heads

in ± corymbiform arrays.

in corymbiform-scorpioid arrays.

Cypselae

3–5 mm;

pappi fuscous to purplish, outer scales 25–30+, 0.5–1 mm, contrasting with 25–30+, 5–7 mm inner bristles.

2.5–3.5 mm;

pappi usually purplish, sometimes stramineous, outer scales 20–25, 0.5–1 mm, contrasting with 35–40+, 4.5–6+ mm inner bristles.

2n

= 34.

= 34.

Vernonia arkansana

Vernonia gigantea

Phenology Flowering Aug–Oct. Flowering Jun–Sep.
Habitat Leas, roadsides, stream banks, in sand or on limestone Flood plains
Elevation 200–300 m (700–1000 ft) 10–300 m (0–1000 ft)
Distribution
from FNA
AR; KS; MO; OK
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; FL; GA; IL; IN; KS; KY; LA; MD; MI; MO; MS; NC; NE; OH; OK; PA; SC; TN; TX; VA; WV; ON
[WildflowerSearch map]
[BONAP county map]
Discussion

Vernonia arkansana was published in April, V. crinita in October 1838.

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

Source FNA vol. 19, p. 208. FNA vol. 19, p. 212.
Parent taxa Asteraceae > tribe Vernonieae > Vernonia Asteraceae > tribe Vernonieae > Vernonia
Sibling taxa
V. acaulis, V. angustifolia, V. baldwinii, V. blodgettii, V. fasciculata, V. flaccidifolia, V. gigantea, V. glauca, V. larseniae, V. lettermannii, V. lindheimeri, V. marginata, V. missurica, V. noveboracensis, V. pulchella, V. texana
V. acaulis, V. angustifolia, V. arkansana, V. baldwinii, V. blodgettii, V. fasciculata, V. flaccidifolia, V. glauca, V. larseniae, V. lettermannii, V. lindheimeri, V. marginata, V. missurica, V. noveboracensis, V. pulchella, V. texana
Synonyms V. crinita Chrysocoma gigantea, V. altissima, V. altissima var. taeniotricha, V. gigantea subsp. ovalifolia, V. ovalifolia
Name authority de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 7: 264. (1838) (Walter) Branner & Coville: Rep. (Annual) Arkansas Geol. Surv. 4: 189. (1891)
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