Helianthus debilis |
Helianthus cusickii |
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cucumberleaf sunflower, weak sunflower |
Cusick's sunflower, turnip-root sunflower |
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Habit | Annuals or perennials, 30–200 cm (taprooted). | Perennials, 60–120 cm (taproots stout, parsniplike). | ||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
erect to prostrate, 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, petioles 0–1 cm; blades (light to dark green, 3-nerved at bases) lance-linear to lanceolate, 5–15 × 0.5–2.5 cm, bases cuneate, margins entire, abaxial faces glabrous or scabro-hispid, gland-dotted. |
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Peduncles | 9–50 cm. |
2–10 cm. |
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Involucres | hemispheric, 10–22 mm diam. |
hemispheric, 12–28 mm diam. |
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Ray florets | 11–20; laminae 12–23 mm. |
12–16; laminae 20–35 mm (abaxial faces gland-dotted). |
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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). |
40+; corollas 6.5–7.5 mm, lobes yellow; anthers usually dull orange or orange-brown, sometimes yellowish, appendages dull orange to yellowish. |
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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. |
12–18, lanceolate, 11–18 × 1.5–3 mm, apices acute to acuminate, abaxial faces gland-dotted. |
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Heads | 1–3. |
1–3. |
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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 mm, glabrate; pappi of 2 aristate scales 3–4.2 mm. |
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Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
(lanceolate) 9–13 mm, subentire or 3-toothed (apices sparsely hairy, sometimes gland-dotted). |
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2n | = 34. |
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Helianthus debilis |
Helianthus cusickii |
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Phenology | Flowering late spring–summer. | |||||||||||||||||
Habitat | Dry slopes, open woods | |||||||||||||||||
Elevation | 600–2000 m (2000–6600 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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CA; ID; NV; OR; WA
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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.) |
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Key |
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Source | FNA vol. 21, p. 150. | FNA vol. 21, p. 168. | ||||||||||||||||
Parent taxa | Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus | Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus | ||||||||||||||||
Sibling taxa | ||||||||||||||||||
Subordinate taxa | ||||||||||||||||||
Name authority | Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 367. (1841) | A. Gray: Proc. Amer. Acad. Arts 21: 413. (1886) | ||||||||||||||||
Web links |