Helianthus debilis |
Helianthus debilis subsp. cucumerifolius |
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cucumberleaf sunflower, weak sunflower |
cucumberleaf sunflower |
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Habit | Annuals or perennials, 30–200 cm (taprooted). | |||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
erect, hispid. |
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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. |
blades 4–9 cm, margins usually shallowly, regularly serrate, abaxial faces sometimes gland-dotted. |
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Peduncles | 9–50 cm. |
25–50 cm. |
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Involucres | hemispheric, 10–22 mm diam. |
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Ray florets | 11–20; laminae 12–23 mm. |
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Ray laminae | (15–)20–30 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). |
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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. |
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Heads | 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. |
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Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
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Discs | 16–18(–20) mm diam. 2n = 34. |
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Helianthus debilis |
Helianthus debilis subsp. cucumerifolius |
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Phenology | Flowering spring–fall. | |||||||||||||||||
Habitat | Open areas, sandy soils | |||||||||||||||||
Elevation | 10–100+ m (0–300+ 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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CT; FL; GA; LA; MA; MD; MI; NC; NH; NY; PA; RI; SC; TX; VA; VT; WV |
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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. 151. | ||||||||||||||||
Parent taxa | Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus | Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus > Helianthus debilis | ||||||||||||||||
Sibling taxa | ||||||||||||||||||
Subordinate taxa | ||||||||||||||||||
Synonyms | H. cucumerifolius, H. debilis var. cucumerifolius | |||||||||||||||||
Name authority | Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 367. (1841) | (Torrey & A. Gray) Heiser: Madroño 13: 160. (1956) | ||||||||||||||||
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