Helianthus decapetalus
Helianthus carnosus
hélianthe à dix rayons, thin-leaf sunflower
lakeside sunflower
erect, glabrous.
erect, (unbranched) glabrous, eglandular.
cauline; opposite (proximal or all) or alternate (distal);
petioles (1–)2–5 cm;
blades (green, 3-nerved distal to bases) lanceolate to ovate, 7–21 × 4–10 cm, bases rounded to cuneate (often shortly decurrent onto petioles), margins usually serrate (moderately to notably in larger leaves), abaxial faces ± scabro-hispidulous, relatively sparsely gland-dotted.
mostly basal; opposite (proximal) or alternate;
petioles obscure (intergrading with blades);
blades lanceolate to lance-linear or linear, 10–25 × 0.5–1.5 cm, bases cuneate, margins entire, faces glabrous, not gland-dotted (cauline 1–5 pairs, smaller).
2–12 cm (not gland-dotted).
5–10 cm.
broadly hemispheric, 17–25 mm diam.
8–12;
laminae 20–25 mm.
12–17;
laminae 20–40 mm, (abaxial faces not gland-dotted).
40+;
corollas 6.5–7.2 mm, lobes yellow;
anthers usually dark brown to black (rarely reddish brown), appendages dark or reddish brown.
100+;
corollas 6–6.5 mm, lobes yellow;
anthers dark, appendages yellowish or dark.
20–25 (often reflexed), lance-linear to lanceolate, 11–16 × 2–3 mm (sometimes leaflike, longest surpassing discs by 1/2+ their lengths), (margins ciliate) apices attenuate, abaxial faces strigillose to glabrate, not gland-dotted.
(green with purple veins) 25–30, ovate to lance-ovate, 8–16 × 3–5 mm, apices acuminate, abaxial faces usually glabrous, sometimes puberulent.
3–6(–10).
1(–3).
3.5–5 mm;
pappi of 2 aristate scales 3–4 mm.
3 mm, glabrous;
pappi of 2 aristate scales 1.5–2 mm plus 2–4 erose scales 0.3–0.6 mm.
-lucres hemispheric, 12–25 mm diam.
8–10 mm, 3-toothed.
8–9 mm, 3-toothed (middle teeth long-acuminate).
= 34, 68.
= 34.
Helianthus decapetalus
Helianthus carnosus
Helianthus decapetalus is sometimes confused with Heliopsis helianthoides because of shared habitats and superficial similarities. The tetraploid cytotype of H. decapetalus intergrades (and apparently hybridizes) with H. strumosus, particularly in the southern Appalachians; individual specimens can be difficult to place in one or the other species. In addition to morphologic differences, H. decapetalus usually occurs in more mesic habitats, particularly along watercourses; H. strumosus is found in drier sites such as roadside slopes. Helianthus ×multiflorus Linnaeus is a sterile hybrid, often with “doubled” heads (in which disc florets are replaced by ray florets); it is cultivated and is sometimes included within H. decapetalus, e.g., H. decapetalus var. multiflorus (Linnaeus) A. Gray; its parents are H. decapetalus and H. annuus.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Helianthus carnosus is distinctive in morphology and is known from relatively few counties in northeastern Florida.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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