Vernonia

Schreber

Gen. Pl. 2: 541. 1791.

Common names: Ironweed
Etymology: For William Vernon, d. 1711, English botanist
Treatment appears in FNA Volume 19. Treatment on page 206. Mentioned on page 58, 67, 200, 201, 207.
 TaxonIllustrator 
FNA19 P15 Cyanthillium cinereum.jpegCyanthillium cinereum
Centratherum punctatum
Vernonia arkansana
Bee F. Gunn
Bee F. Gunn
Bee F. Gunn
FNA19 P16 Veronia noveboracensis.jpegVernonia noveboracensis
Vernonia lindheimeri
Vernonia baldwinii
Bee F. Gunn
Bee F. Gunn
Bee F. Gunn

Perennials, 2–20 (–30+) dm (rhizomatous or not). Leaves 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). Heads discoid, ± pedunculate, not subtended by foliaceous bracts, (6–) 40–100+ in ± corymbiform to paniculiform arrays (6–) 10–25+ cm diam. Involucres ± campanulate to obconic or hemispheric, 3–8 (–11+) mm diam. Phyllaries 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. Florets 9–30 (–65+); corollas usually purplish or pink (rarely white), tubes longer than funnelform throats, lobes 5, lance-linear, ± equal. Cypselae ± 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.

Distribution

Mainly c, e North America, n Mexico, 2–3 species in South America

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).

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) Vernonia 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+ Vernonia 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. Vernonia angustifolia
5 Leaf blades (mid stem) oblanceolate to lance-linear, 3–7 cm × (5–)10–20+ mm Vernonia pulchella
6 Leaf blade l/w = 2.5–3.5(–4); pappi stramineous to whitish, outer bristles or subulate scales intergrading with inner ones Vernonia glauca
6 Leaf blade l/w = (3.3–)4–6+; pappi fuscous to purplish, outer scales contrasting with inner bristles Vernonia 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+ Vernonia larseniae
8 Leaf blades adaxially usually glabrate, sometimes sparsely arachno-tomentose; florets 12–24+ Vernonia 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 Vernonia texana
10 Involucres campanulate; cypselae 3–5 mm > 11
11 Leaf blades 1–3+ mm wide; florets 10–12+ Vernonia 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 Vernonia marginata
12 Peduncles 1–8(–12+) mm; involucres 5–7(–8+) mm; phyllary tips acute or rounded-apiculate; inner pappi 5–7+ mm Vernonia fasciculata
13 Leaf blades 2–8+ mm wide Vernonia blodgettii
13 Leaf blades 15–40(–75+) mm wide > 14
14 Stems glabrous Vernonia 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 Vernonia 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 Vernonia missurica
16 Involucres broadly campanulate to hemispheric, 4–6(–8+) × 4–7+ mm; (phyllaries often resin-gland-dotted); florets (15–)20–25(–35+) Vernonia baldwinii

"dm" is not declared as a valid unit of measurement for this property."dm" is not declared as a valid unit of measurement for this property.

... more about "Vernonia"
resin-gland-dotted +, glabrous +, glabrate +, tomentose +  and pannose +
resin-gland-dotted +  and glabrate +
acute;attenuate +
scarious +
ovate +  and lanceolate +
less corymbiform +  and paniculiform +
indeterminate +  and determinate +
10 cm100 mm <br />0.1 m <br /> (25 cm250 mm <br />0.25 m <br />) +
John L. Strother +
Schreber +
cuneate +
compound +  and simple +
filiform;linear;filiform;linear;spatulate;oblanceolate;lanceolate;elliptic;ovate +
ribbed;nerved;ribbed;nerved;smooth +
lance-linear;more or less lanceolate +
Ironweed +
zygomorphic +, actinomorphic +  and (3-)5-merous +
pink +  and purplish +
resin-gland-dotted +, more or less strigillose +  and hirtellous +
fertile +  and bisexual +
Mainly c +, e North America +, n Mexico +  and 2–3 species in South America +
For William Vernon, d. 1711, English botanist +
gland-dotted +
sparsely strigillose +  and tomentose +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
pedunculate +
in usually determinate , rarely indeterminate , arrays +  and singly +
indeterminate +
each +  and sessile +
0.3 cm3 mm <br />0.003 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
less campanulate;obconic or hemispheric +
petiolate +  and sessile +
ovate +  and lanceolate or subulate +
2-carpellate +
persistent +
18 +  and 70 +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
gleason1922b +, jones1964a +, jones1978a +  and shinners1950a +
subulate +  and setiform +
exalbuminous +
prostrate +  and ascending +
appendaged +  and truncate +
hirsutulous +
Compositae +
Vernonia +
Asteraceae tribe Vernonieae +
filiform +, subulate +, acuminate +  and rounded +