Helianthus debilis |
Helianthus laciniatus |
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cucumberleaf sunflower, weak sunflower |
alkali sunflower |
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Habit | Annuals or perennials, 30–200 cm (taprooted). | Perennials, 50–120(–200) cm. | ||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
erect, usually strigose or hispid to glabrate. |
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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; opposite or alternate; sessile; blades (green or grayish, 1- or 3-nerved) lanceolate, 5–9 × 0.5–3.5 cm, bases ± cuneate, margins entire or irregularly toothed to lobed, faces strigose to strumose, gland-dotted (adaxial sometimes glaucous). |
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Peduncles | 9–50 cm. |
4–13 cm. |
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Involucres | hemispheric, 10–22 mm diam. |
hemispheric, 10–24 mm diam. |
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Ray florets | 11–20; laminae 12–23 mm. |
14–20; laminae ca. 8–11 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). |
40+; corollas 4.8–5.8 mm, lobes reddish; anthers purplish, appendages reddish (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. |
16–21, lanceolate, 6–7.5 × 1.8–2.5 mm (often subequal), (margins ciliate) apices acute, abaxial faces hispidulous or strigose to glabrate, gland-dotted. |
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Heads | 1–3. |
1–9. |
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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. |
2.7–3.5 mm, glabrate; pappi of 2(–3) aristate scales 1.4–2.5 mm. |
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Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
7–7.8 mm, entire or 3-toothed (apices obtuse to acute, hispid-ciliate to glabrate). |
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2n | = 34. |
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Helianthus debilis |
Helianthus laciniatus |
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Phenology | Flowering summer–fall. | |||||||||||||||||
Habitat | Open, dry, alkaline soils | |||||||||||||||||
Elevation | 1000–1200 m (3300–3900 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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NM; TX; Mexico
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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 laciniatus reaches the northern extent of its range in New Mexico and Texas; it is relatively common in the Chihuahuan Desert areas of Mexico. It is similar to H. ciliaris; it usually has hairy stems as well as denser leaf indument that includes a greater number of subsessile, glandular hairs. (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 | ||||||||||||||||||
Synonyms | H. crenatus, H. heiseri | |||||||||||||||||
Name authority | Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 367. (1841) | A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 84. (1849) | ||||||||||||||||
Web links |