Helianthus decapetalus
Helianthus eggertii
hélianthe à dix rayons, thin-leaf sunflower
Eggert's sunflower
erect, glabrous.
erect, glabrous (distinctively bluish, glacous).
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.
cauline; all or mostly opposite;
sessile;
blades (1-nerved) lanceolate to lance-ovate, 7–16.5 × 1.5–3.5 cm, bases cuneate, margins entire or serrulate, faces glabrous (abaxial) or strumose (adaxial), gland-dotted.
2–12 cm (not gland-dotted).
1–4 cm.
hemispheric, 10–25 mm diam.
8–12;
laminae 20–25 mm.
10–18;
laminae 15–20 mm.
40+;
corollas 6.5–7.2 mm, lobes yellow;
anthers usually dark brown to black (rarely reddish brown), appendages dark or reddish brown.
70+;
corollas 5–7 mm, lobes yellow;
anthers dark, appendages dark or ± yellowish.
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.
30–38, lanceolate, 12–16 × 3.5–4.5 mm, (margins ciliate) apices acuminate, abaxial faces glabrate, not gland-dotted.
3–6(–10).
1–5.
3.5–5 mm;
pappi of 2 aristate scales 3–4 mm.
4–6 mm, glabrous;
pappi of 2 aristate scales 3–4 mm plus 0–1 deltate scales 0.5–1 mm.
-lucres hemispheric, 12–25 mm diam.
8–10 mm, 3-toothed.
9–11 mm, entire or ± 3-toothed (apices deltate).
= 34, 68.
= 102.
Helianthus decapetalus
Helianthus eggertii
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.)
Helianthus eggertii is similar to H. strumosus and H. laevigatus; it is distinguished by the distinctive blue coloration of stems and leaves and by the leaves usually 1-nerved, in contrast to the 3-nerved condition typical for the genus. It is listed federally as an endangered species; R. L. Jones (1994) found it to be more common than was previously thought, and it is now in the process of being removed from the federal list.
of conservation concern
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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