Helianthus debilis |
Helianthus longifolius |
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cucumberleaf sunflower, weak sunflower |
longleaf sunflower |
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Habit | Annuals or perennials, 30–200 cm (taprooted). | Perennials, 10–30 cm (with crown buds). | ||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
(green or purplish) erect, glabrous. |
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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. |
mostly basal; opposite; petioles 0–1 cm; blades linear to narrowly obovate, 13–30 × 0.7–2 cm, bases cuneate, margins entire or obscurely serrate, faces glabrous, not gland-dotted (cauline smaller). |
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Peduncles | 9–50 cm. |
4–11 cm. |
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Involucres | hemispheric, 10–22 mm diam. |
hemispheric, 8–12 mm diam. |
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Ray florets | 11–20; laminae 12–23 mm. |
8–13; laminae 10–19 mm (abaxial faces not 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). |
35+; corollas 4.2–5.5 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. |
18–23, linear-linear, 5–11 × 1–2.5 mm, (margins ciliolate) apices ± attenuate, abaxial faces glabrate or glabrous. |
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Heads | 1–3. |
3–12. |
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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. |
2–3 mm, glabrate; pappi of 2 aristate scales 1.4–2.5 mm. |
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Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
6–8 mm, weakly 3-toothed (apices hairy). |
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2n | = 34. |
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Helianthus debilis |
Helianthus longifolius |
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Phenology | Flowering late summer–fall. | |||||||||||||||||
Habitat | Sandstone and granite outcrop edges | |||||||||||||||||
Elevation | 100–600 m (300–2000 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; NC
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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 longifolius is locally escaped from a planting in one county in North Carolina. It is locally abundant where it occurs. It is not similar to or closely related to any other species; natural hybrids of H. longifolius with H. atrorubens and H. occidentalis are known. (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. 156. | ||||||||||||||||
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) | Pursh: Fl. Amer. Sept. 2: 571. (1813) | ||||||||||||||||
Web links |