Helianthus debilis |
Helianthus gracilentus |
|||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
cucumberleaf sunflower, weak sunflower |
slender sunflower |
|||||||||||||||||
Habit | Annuals or perennials, 30–200 cm (taprooted). | Perennials, 60–200 cm (taprooted). | ||||||||||||||||
Stems | decumbent to erect, glabrous, hirsute, or puberulent. |
(reddish or purplish) erect, hairy. |
||||||||||||||||
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; all or mostly opposite; petioles 0–3 cm; blades (1- or 3-nerved) lanceolate to lance-ovate, 5–11 × 2–3.5 cm, bases cuneate, margins entire or serrate, abaxial faces hispid, gland-dotted. |
||||||||||||||||
Peduncles | 9–50 cm. |
2.5–30 cm. |
||||||||||||||||
Involucres | hemispheric, 10–22 mm diam. |
hemispheric, 13–20 mm diam. |
||||||||||||||||
Ray florets | 11–20; laminae 12–23 mm. |
13–21; laminae 15–25 mm (abaxial faces gland-dotted). |
||||||||||||||||
Disc florets | 30+; corollas 4.5–5 mm, lobes usually reddish, sometimes yellow; anthers dark, appendages dark (style branches usually reddish, rarely yellow). |
50+; corollas 5–6 mm, lobes reddish; anthers reddish brown, appendages yellow or dull orange (style branches yellow). |
||||||||||||||||
Phyllaries | 20–30, lanceolate, 8–17 × 1–3 mm, apices acute to long-attenuate, abaxial faces glabrous or ± hispid, not gland-dotted. |
20–25, lanceolate, 4–8 × 1.5–3 mm, (margins ciliate) apices acute, abaxial faces hispidulous, gland-dotted. |
||||||||||||||||
Heads | 1–3. |
1–5. |
||||||||||||||||
Cypselae | 2.5–3.2 mm, glabrous or sparsely hairy; pappi of 2 lanceolate or lance-linear scales 1.2–2.5 mm. |
3–4 mm, glabrate; pappi of 2 aristate scales 2.5–3 mm. |
||||||||||||||||
Paleae | 7.5–8 mm, apices 3-toothed (middle teeth acuminate, usually glabrous or hispid, sometimes ± villous or bearded). |
8–9 mm, subentire to weakly 3-toothed (apices acute, ciliate, gland-dotted). |
||||||||||||||||
2n | = 34. |
|||||||||||||||||
Helianthus debilis |
Helianthus gracilentus |
|||||||||||||||||
Phenology | Flowering late spring–fall. | |||||||||||||||||
Habitat | Dry slopes | |||||||||||||||||
Elevation | 0–1800 m (0–5900 ft) | |||||||||||||||||
Distribution |
AL; CT; FL; GA; LA; MA; MD; MI; MS; NC; NH; NY; PA; RI; SC; TX; VA; VT; WV
|
CA; Mexico (Baja California)
|
||||||||||||||||
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.) |
|||||||||||||||||
Key |
|
|||||||||||||||||
Source | FNA vol. 21, p. 150. | FNA vol. 21, p. 168. | ||||||||||||||||
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) | A. Gray: Proc. Amer. Acad. Arts 11: 77. (1876) | ||||||||||||||||
Web links |