Helianthus debilis |
Helianthus verticillatus |
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cucumberleaf sunflower, weak sunflower |
whorled sunflower |
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Habit | Annuals or perennials, 30–200 cm (taprooted). | Perennials, 200–300 cm (rhizomatous). | ||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
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; usually whorled (3s–6s), sometimes opposite; sessile or subsessile, petioles 0–1 cm; blades linear to lanceolate, 7.5–18.5 × 0.7–3 cm, bases cuneate, margins serrulate or entire (flat), faces puberulent (abaxial) or hispid-strumose (adaxial), gland-dotted. |
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Peduncles | 9–50 cm. |
1–10 cm. |
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Involucres | hemispheric, 10–22 mm diam. |
broadly campanulate, 15–20 mm diam. |
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Ray florets | 11–20; laminae 12–23 mm. |
10–19; laminae 20–26 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). |
150+; corollas 5–7 mm, lobes yellow; anthers dark, appendages yellow. |
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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. |
45–55, lance-linear, 12–18 × 2–2.5 mm, (margins ciliate) apices long-attenuate, abaxial faces glabrate to sparsely puberulent, gland-dotted. |
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Heads | 1–3. |
(1–)3–7+. |
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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, glabrous; pappi of 2 aristate scales 2.2–2.5 mm. |
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Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
5–8 mm, entire or 3-toothed (apices ciliate). |
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2n | = 34. |
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Helianthus debilis |
Helianthus verticillatus |
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Phenology | Flowering late summer–fall. | |||||||||||||||||
Habitat | Wet prairies | |||||||||||||||||
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 verticillatus is relatively uncommon and was recently rediscovered in scattered locations; it is a candidate for federal listing as an endangered species. It has been suggested to be a hybrid of H. angustifolius and H. eggertii or H. grosseserratus; no supporting evidence has been found to corroborate that suggestion. (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. 166. | ||||||||||||||||
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) | Small: Bull. Torrey Bot. Club 25: 479. (1898) | ||||||||||||||||
Web links |