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woolly ironweed

ironweed

Habit Plants 2–5(–8+) dm. Perennials, 2–20(–30+) dm (rhizomatous or not).
Stems

± pannose.

Leaves

mostly cauline;

blades linear, 5–8 cm × 2–4 mm, l/w = 17–25(–40), abaxially densely sericeo-tomentose, adaxially usually glabrate, sometimes sparsely arachno-tomentose.

usually mostly cauline (rarely mostly basal or basal and cauline);

sessile or petiolate;

blades ovate, elliptic, lanceolate, oblanceolate, spatulate, linear, or filiform, bases usually ± cuneate (rounded-truncate in V. pulchella), margins usually toothed (rarely entire), apices acute to attenuate, abaxial faces usually ± scabrellous to strigillose or tomentose to pannose, sometimes glabrate or glabrous, usually resin-gland-dotted (sometimes ± pitted), adaxial faces ± scabrellous or glabrate, sometimes resin-gland-dotted (rarely pitted).

Peduncles

5–35 mm.

Involucres

± obconic to campanulate, 6–10 × 5–8 mm.

± campanulate to obconic or hemispheric, 3–8(–11+) mm diam.

Florets

12–24+.

9–30(–65+);

corollas usually purplish or pink (rarely white), tubes longer than funnelform throats, lobes 5, lance-linear, ± equal.

Phyllaries

40–50+ in 5–6+ series, sericeo-tomentose, including margins, the outer lance-ovate, 1–2 mm, the inner lanceolate to lance-linear, 6–7(–9+) mm, tips acute.

18–70+ in 4–7+ series, the outer ovate to lanceolate or subulate, inner ± lanceolate to oblong, all ± chartaceous, margins entire, often ciliolate, tips rounded (then sometimes apiculate), or acuminate, subulate, or filiform, faces glabrous or sparsely strigillose to tomentose, sometimes ± gland-dotted.

Heads

in corymbiform arrays.

discoid, ± pedunculate, not subtended by foliaceous bracts, (6–)40–100+ in ± corymbiform to paniculiform arrays (6–)10–25+ cm diam.

Cypselae

3–4 mm;

pappi stramineous to purplish, outer scales 20+, 0.6–1.1 mm, contrasting with 20+, 6–7+ mm inner bristles.

± columnar, sometimes arcuate, 8–10-ribbed, glabrous or ± strigillose to hirtellous, often resin-gland-dotted;

pappi persistent, of 20–30+ outer, erose to subulate scales or bristles plus 20–40+ inner, longer, subulate to setiform scales or bristles.

x

= 17.

2n

= 34.

Vernonia lindheimeri

Vernonia

Phenology Flowering Jun–Aug.
Habitat Calcareous soils, rocky banks
Elevation 300 m (1000 ft)
Distribution
from FNA
AR; TX; Mexico (Coahuila)
[WildflowerSearch map]
[BONAP county map]
from USDA
e North America; n Mexico; Mainly c North America; 2–3 species in South America
[BONAP county map]
Discussion

Species 20 or so (17 in the flora).

The circumscription of Vernonia adopted here follows that of H. Robinson (1999).

Vernonias hybridize; almost every one of the species recognized here has been noted as sometimes hybridizing with one or more others. Putative hybrid plants are usually intermediate between parentals in some traits; such plants may not “key” satisfactorily to any of the species treated here. Some putative hybrids have been named. Vernonia guadalupensis is “without much doubt a hybrid of V. baldwinii Torrey and V. lindheimeri Engelmann & Gray” (L. H. Shinners 1950); V. vulturina Shinners (known only from the type collection) may be a product of V. baldwinii × V. marginata; V. ×georgiana Bartlett may refer to V. acaulis × V. angustifolia. Additional putative hybrids (S. B. Jones 1964) are V. ×concinna Gleason (V. ovalifolia × V. angustifolia), V. ×dissimilis Gleason (V. altissima × V. angustifolia), and V. ×recurva Gleason (V. pulchella × V. angustifolia).

In the key and descriptions, “l/w = ” refers to lengths divided by widths for blades of leaves; lengths of phyllaries include subulate to filiform tips (if any).

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

Key
1. Phyllary tips usually subulate to filiform, sometimes acuminate
→ 2
1. Phyllary tips usually acute to rounded or rounded-apiculate, seldom acuminate
→ 7
2. Leaves mostly basal (cauline leaves much smaller with narrower blades)
V. acaulis
2. Leaves mostly cauline (basal leaves wanting at flowering or ± like cauline)
→ 3
3. Involucres 11–15 mm diam.; phyllaries (50–)60–70+; florets 50–100+
V. arkansana
3. Involucres 4–8(–10) mm diam.; phyllaries 22–46(–60+); florets 12–45(–65)
→ 4
4. Involucres ± campanulate to obconic; florets 12–24(–30+)
→ 5
4. Involucres ± hemispheric; florets 30–45(–65)
→ 6
5. Leaf blades (mid stem) lance-linear to filiform, 5–12 cm × 2–4(–8+) mm.
V. angustifolia
5. Leaf blades (mid stem) oblanceolate to lance-linear, 3–7 cm × (5–)10–20+ mm
V. pulchella
6. Leaf blade l/w = 2.5–3.5(–4); pappi stramineous to whitish, outer bristles or subulate scales intergrading with inner ones
V. glauca
6. Leaf blade l/w = (3.3–)4–6+; pappi fuscous to purplish, outer scales contrasting with inner bristles
V. noveboracensis
7. Phyllaries densely sericeo-tomentose to pannose
→ 8
7. Phyllaries usually glabrous or puberulent to scabrellous (rarely sparsely arachno-tomentose)
→ 9
8. Leaf blades adaxially densely sericeo-tomentose; florets 40–50+
V. larseniae
8. Leaf blades adaxially usually glabrate, sometimes sparsely arachno-tomentose; florets 12–24+
V. lindheimeri
9. Leaf blades abaxially glabrate (and pitted; best seen at 10× or greater, pits containing awl-shaped hairs or glands 0.1–0.5+ mm)
→ 10
9. Leaf blades abaxially scabrellous, scaberulous, or puberulous to tomentose or pannose (not pitted)
→ 13
10. Involucres obconic to hemispheric; cypselae 2–3 mm
V. texana
10. Involucres campanulate; cypselae 3–5 mm
→ 11
11. Leaf blades 1–3+ mm wide; florets 10–12+
V. lettermannii
11. Leaf blades (2.5–)5–20(–40) mm wide; florets (10–)15–25+
→ 12
12. Peduncles (3–)10–35 mm; involucres (7–)9–11 mm; phyllary tips ± acuminate; inner pappi 8–9+ mm
V. marginata
12. Peduncles 1–8(–12+) mm; involucres 5–7(–8+) mm; phyllary tips acute or rounded-apiculate; inner pappi 5–7+ mm
V. fasciculata
13. Leaf blades 2–8+ mm wide
V. blodgettii
13. Leaf blades 15–40(–75+) mm wide
→ 14
14. Stems glabrous
V. flaccidifolia
14. Stems puberulent to tomentose (sometimes glabrescent)
→ 15
15. Leaf blades abaxially usually scabrellous (with appressed, awl-shaped hairs), sometimes glabrescent, not or sparsely resin-gland-dotted
V. gigantea
15. Leaf blades abaxially usually puberulous to tomentose or pannose (with ± erect, ± curled hairs), seldom glabrescent, conspicuously resin-gland-dotted
→ 16
16. Involucres broadly campanulate to urceolate, (6–)7–10+ × 5–9+ mm; (phyllaries seldom resin-gland-dotted); florets 30–55
V. missurica
16. Involucres broadly campanulate to hemispheric, 4–6(–8+) × 4–7+ mm; (phyllaries often resin-gland-dotted); florets (15–)20–25(–35+)
V. baldwinii
Source FNA vol. 19, p. 210. FNA vol. 19, p. 206. Author: John L. Strother.
Parent taxa Asteraceae > tribe Vernonieae > Vernonia Asteraceae > tribe Vernonieae
Sibling taxa
V. acaulis, V. angustifolia, V. arkansana, V. baldwinii, V. blodgettii, V. fasciculata, V. flaccidifolia, V. gigantea, V. glauca, V. larseniae, V. lettermannii, V. marginata, V. missurica, V. noveboracensis, V. pulchella, V. texana
Subordinate taxa
V. acaulis, V. angustifolia, V. arkansana, 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
Name authority A. Gray & Engelmann: Proc. Amer. Acad. Arts 1: 46. (1847) Schreber: Gen. Pl. 2: 541. (1791)
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