Helianthus debilis |
Helianthus smithii |
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cucumberleaf sunflower, weak sunflower |
Smith's sunflower |
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Habit | Annuals or perennials, 30–200 cm (taprooted). | Perennials, 70–150 cm (rhizomatous). | ||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
(usually purplish) erect, glabrous (glaucous). |
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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; opposite (proximal) or alternate; petioles to 1.3 cm; blades (light to dark green, 1-nerved) lance-linear to lanceolate, 7–18 × 1–1.8 cm, bases ± cuneate, margins serrulate, abaxial faces ± hispid, gland-dotted. |
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Peduncles | 9–50 cm. |
3–6 cm. |
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Involucres | hemispheric, 10–22 mm diam. |
hemispheric, 5–15 mm diam. |
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Ray florets | 11–20; laminae 12–23 mm. |
6–9; laminae 10–15 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). |
25+; corollas 5.5–6 mm, lobes yellow; anthers dark, appendages dark. |
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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. |
15–20, lanceolate, 6–9 × 2–2.7 mm, (margins ciliate) apices short-acuminate, abaxial faces glabrous or glabrate, not gland-dotted. |
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Heads | 1–3. |
1–5. |
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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. |
2.8–3 mm, glabrate; pappi of 2 aristate scales 1.5–2 mm. |
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Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
5.5–6.5 mm, 3-toothed (gland-dotted). |
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2n | = 68. |
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Helianthus debilis |
Helianthus smithii |
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Phenology | Flowering late summer–fall. | |||||||||||||||||
Habitat | Dry, open woods | |||||||||||||||||
Elevation | 100–300+ m (300–1000+ 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; GA; TN |
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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.) |
Of conservation concern. Helianthus smithii is known from relatively few sites. T. A. Storbeck (1984) concluded that it is a distinct species; he could not rule out the possibility that it might be a hybrid of H. microcephalus and H. strumosus. It may also be an extreme variant of H. strumosus that has relatively narrow leaves and small heads. (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. parviflorus var. attenuatus | |||||||||||||||||
Name authority | Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 367. (1841) | Heiser: Rhodora 66: 346. (1964) | ||||||||||||||||
Web links |