Helianthus debilis |
Helianthus angustifolius |
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cucumberleaf sunflower, weak sunflower |
swamp sneezeweed, swamp sunflower |
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Habit | Annuals or perennials, 30–200 cm (taprooted). | Perennials, 50–150+ cm (with crown buds, rhizomes absent or poorly developed). | ||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
erect, usually ± hairy. |
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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; opposite or alternate; sessile or subsessile; blades (3-nerved near bases) narrowly lanceolate to linear, 8–15 × 0.15–0.5(–1) cm, bases cuneate, margins entire (revolute, abaxial face sometimes obscured by rolled margins), abaxial faces strigose to hispid or hirsute, sometimes (adaxial not) gland-dotted. |
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Peduncles | 9–50 cm. |
5–15 cm. |
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Involucres | hemispheric, 10–22 mm diam. |
shallowly hemispheric, 10–20 mm diam. |
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Ray florets | 11–20; laminae 12–23 mm. |
10–20; laminae 10–20 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). |
75+; corollas 4–4.5 mm, lobes yellow; anthers dark brown or black, appendages dark (style branches usually 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. |
25–32 (loose), lanceolate, 4–9 × 1–2 mm, apices acute to slightly acuminate, abaxial faces usually scabrous, rarely glabrous, usually gland-dotted. |
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Heads | 1–3. |
3–16. |
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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 1.5–2.1 mm. |
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Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
(oblanceolate) 5.5–6.5 mm, entire or ± 3-toothed (apices purplish, mucronate, gland-dotted). |
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2n | = 34. |
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Helianthus debilis |
Helianthus angustifolius |
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Phenology | Flowering late summer–fall. | |||||||||||||||||
Habitat | Open to shaded, usually moist places | |||||||||||||||||
Elevation | 10–700 m (0–2300 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; AR; FL; GA; IA; IN; KY; LA; MD; MO; MS; NC; NJ; OH; OK; PA; SC; TN; TX; VA; 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.) |
The distal parts of Helianthus angustifolius are identical in appearance to those of H. simulans; plants of the latter are taller (200+ cm) and more robust. The leaves are not only narrower in H. angustifolius but also tend to be more strongly revolute (abaxial faces sometimes scarcely visible). (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. 164. | ||||||||||||||||
Parent taxa | Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus | Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus | ||||||||||||||||
Sibling taxa | ||||||||||||||||||
Subordinate taxa | ||||||||||||||||||
Synonyms | H. angustifolius var. planifolius | |||||||||||||||||
Name authority | Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 367. (1841) | Linnaeus: Sp. Pl. 2: 906. (1753) | ||||||||||||||||
Web links |