Helianthus debilis |
Helianthus ciliaris |
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cucumberleaf sunflower, weak sunflower |
blueweed, blueweed sunflower, Texas-blueweed, yerba parda |
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Habit | Annuals or perennials, 30–200 cm (taprooted). | Perennials, 40–70 cm (rhizomatous or with creeping roots, often forming extensive colonies). | ||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
decumbent to ± erect, glabrous or glabrate (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; mostly opposite; sessile; blades (often bluish green, 1- or 3-nerved) linear to lanceolate, 3–7.5 × 0.5–2.2 cm, bases ± cuneate, margins entire or serrate (usually ciliate and undulate), faces glabrous or glabrate to hispid. |
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Peduncles | 9–50 cm. |
(1–)3–13 cm. |
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Involucres | hemispheric, 10–22 mm diam. |
hemispheric, 12–25 mm diam. |
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Ray florets | 11–20; laminae 12–23 mm. |
10–18; laminae 8–9 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). |
35+; corollas 4–6 mm, lobes reddish; anthers brownish red, appendages brownish red (style branches 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. |
16–19, ovate to lance-ovate, 3–8 × 2–3.5 mm, (margins ciliate) apices obtuse to acute, abaxial faces glabrate to ± strigose, not gland-dotted. |
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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. |
3–3.5 mm, glabrous; pappi of 2 aristate scales 1.2–1.5 mm. |
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Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
7–7.5 mm, subentire to 3-toothed (apices obtuse to acute, hairy, gland-dotted). |
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2n | = 68, 102. |
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Helianthus debilis |
Helianthus ciliaris |
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Phenology | Flowering summer–fall. | |||||||||||||||||
Habitat | Roadsides, ditches, cultivated fields, open drainage areas | |||||||||||||||||
Elevation | 10–2600 m (0–8500 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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AZ; CA; CO; IL; KS; NE; NM; NV; OK; TX; UT; Mexico (Chihuahua, Coahuila, Durango, San Luis Potosí, Sonora, Tamaulipas)
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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 ciliaris is considered a noxious weed in some states. It can propagate vegetatively from detached pieces of rhizome and spread aggressively, especially in cultivated fields. It has been noted to occur in Idaho and Washington, where control measures have been taken to eliminate it. (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. 169. | ||||||||||||||||
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) | de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 587. (1836) | ||||||||||||||||
Web links |