Helianthus debilis |
Helianthus resinosus |
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cucumberleaf sunflower, weak sunflower |
resindot sunflower |
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Habit | Annuals or perennials, 30–200 cm (taprooted). | Perennials, 100–300 cm (rhizomatous). | ||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
(often reddish or purplish) erect, hirsute or villous. |
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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 cauline; mostly alternate; petioles 0.5–2 cm (broadly winged); blades lanceolate to ovate, 6.5–20 × 3.2–9 cm, bases gradually narrowed (onto petioles), margins entire or serrate, abaxial faces hirsute to tomentose, gland-dotted. |
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Peduncles | 9–50 cm. |
1–3 cm. |
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Involucres | hemispheric, 10–22 mm diam. |
hemispheric, 15–27 mm diam. |
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Ray florets | 11–20; laminae 12–23 mm. |
10–20; laminae (often light yellow) 18–30 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). |
90+; corollas 8–8.5 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. |
20–30 (squarrose to reflexed, at least tips), lanceolate, 10–21 × 3–5 mm (notably surpassing discs), apices acute to attenuate, abaxial faces hispid to villous, densely gland-dotted (at least toward apices). |
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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. |
5–7 mm, glabrate; pappi of 2 aristate scales 2.4–2.6 mm. |
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Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
9–11 mm, 3-toothed (gland-dotted). |
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2n | = 102. |
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Helianthus debilis |
Helianthus resinosus |
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Phenology | Flowering late summer–fall. | |||||||||||||||||
Habitat | Roadsides, open areas | |||||||||||||||||
Elevation | 0–900+ m (0–3000+ 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; FL; GA; MS; NC; SC
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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.) |
Consistent with its epithet, Helianthus resinosus has abundant subsessile glandular hairs (“resin dots”) on its leaves, phyllaries, paleae, and ray laminae. It intergrades and has been reported to hybridize with H. tuberosus. It is cultivated and usually sold under the long-misapplied name H. tomentosus Michaux. (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. 162. | ||||||||||||||||
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: Fl. S.E. U.S., 1269, 1340. (1903) | ||||||||||||||||
Web links |