Helianthus debilis |
Helianthus strumosus |
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cucumberleaf sunflower, weak sunflower |
hélianthe scrofuleux, pale-leaf sunflower, paleleaf woodland sunflower, rough sunflower, rough-leaf sunflower |
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Habit | Annuals or perennials, 30–200 cm (taprooted). | Perennials, 100–200 cm (rhizomatous). | ||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
erect, glabrous or glabrate. |
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Leaves | mostly cauline; mostly alternate; petioles 1–7 cm; blades deltate-ovate, lance-ovate, or ovate, 2.5–14 × 1.8–13 cm, bases cordate to truncate or broadly cuneate, margins subentire to serrate, abaxial faces glabrate to hispid, not gland-dotted. |
cauline; mostly opposite, sometimes alternate (distal); petioles 1–3 cm; blades (light to dark green, 3-nerved distal to bases) lanceolate to lance-ovate or ovate, 7–18 × 2–10 cm, bases subcordate to ± cuneate, margins entire to ± serrate, abaxial faces glabrous or tomentulose, usually densely gland-dotted. |
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Peduncles | 9–50 cm. |
1–9 cm. |
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Involucres | hemispheric, 10–22 mm diam. |
cylindric to hemispheric, 8–20 mm diam. |
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Ray florets | 11–20; laminae 12–23 mm. |
10–20; laminae ca. 12–20(–30) mm. |
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Disc florets | 30+; corollas 4.5–5 mm, lobes usually reddish, sometimes yellow; anthers dark, appendages dark (style branches usually reddish, rarely yellow). |
35+; corollas 5.5–6.5 mm, lobes yellow; anthers dark, appendages dark or reddish brown. |
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Phyllaries | 20–30, lanceolate, 8–17 × 1–3 mm, apices acute to long-attenuate, abaxial faces glabrous or ± hispid, not gland-dotted. |
18–25 (erect, loose, or squarrose), lanceolate, 5.5–10 × 1.5–3 mm (equaling or slightly surpassing discs), (margins usually ciliate) apices acute to acuminate, abaxial faces glabrous or hispidulous, usually not gland-dotted. |
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Heads | 1–3. |
3–15. |
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Cypselae | 2.5–3.2 mm, glabrous or sparsely hairy; pappi of 2 lanceolate or lance-linear scales 1.2–2.5 mm. |
4–5.5 mm, glabrate; pappi of 2 aristate scales (1–)2–2.5 mm. |
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Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
5.3–6.5 mm, 3-toothed. |
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2n | = 68, 102. |
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Helianthus debilis |
Helianthus strumosus |
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Phenology | Flowering late summer–fall. | |||||||||||||||||
Habitat | Woods, roadsides, prairies | |||||||||||||||||
Elevation | 0–1500 m (0–4900 ft) | |||||||||||||||||
Distribution |
AL; CT; FL; GA; LA; MA; MD; MI; MS; NC; NH; NY; PA; RI; SC; TX; VA; VT; WV
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AL; AR; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; ND; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; VT; WI; WV; ON; QC
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Discussion | Subspecies 5 (5 in the flora). C. B. Heiser (1956) placed 8 subspecies in Helianthus debilis; he noted that alternative taxonomic treatments might recognize these in as many as three species, or expand the single species to include H. petiolaris. Later, Heiser et al. (1969) separated three of the subspecies as H. praecox. Isozyme data (R. P. Wain 1982, 1983; L. H. Rieseberg and M. F. Doyle 1989) show that all are closely related. Documented hybridization with H. annuus further complicates the situation. The treatment by Heiser et al. is followed here. Helianthus debilis is adventive beyond the Atlantic and Gulf coasts of the United States. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Helianthus strumosus is variable, particularly for leaf shape and indument; sufficient study has not been undertaken to evaluate whether regional forms deserve taxonomic recognition. Hybridization with other polyploids, including H. decapetalus, H. hirsutus, and H. tuberosus, further complicates the situation. It differs from H. tuberosus in having glabrous (or glabrate) stems and in lacking tubers. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 21, p. 150. | FNA vol. 21, p. 159. | ||||||||||||||||
Parent taxa | Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus | Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus | ||||||||||||||||
Sibling taxa | ||||||||||||||||||
Subordinate taxa | ||||||||||||||||||
Synonyms | H. montanus, H. saxicola | |||||||||||||||||
Name authority | Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 367. (1841) | Linnaeus: Sp. Pl. 2: 905. (1753) | ||||||||||||||||
Web links |