Helianthus resinosus
Helianthus paradoxus
resindot sunflower
Paradox sunflower, Pecos sunflower
(often reddish or purplish) erect, hirsute or villous.
erect, glabrous or ± hispid.
mostly cauline; mostly alternate;
petioles 0.5–2 cm (broadly winged);
blades lanceolate to ovate, 6.5–20 × 3.2–9 cm, bases gradually narrowed (onto petioles), margins entire or serrate, abaxial faces hirsute to tomentose, gland-dotted.
mostly cauline; opposite (proximal) or mostly alternate;
petioles 1.5–6 cm;
blades lanceolate to lance-ovate, 7–17.5 × 1.7–8.5 cm, bases cuneate, margins entire or (larger leaves) toothed, abaxial faces ± scabrous, not gland-dotted.
1–3 cm.
12–18 cm.
hemispheric, 15–27 mm diam.
hemispheric, 15–20 mm diam.
10–20;
laminae (often light yellow) 18–30 mm.
12–20;
laminae 20–30 mm.
90+;
corollas 8–8.5 mm, lobes yellow;
anthers dark, appendages dark.
50+;
corollas 5–5.5 mm, lobes reddish;
anthers dark, appendages yellowish or dark (style branches reddish).
20–30 (squarrose to reflexed, at least tips), lanceolate, 10–21 × 3–5 mm (notably surpassing discs), apices acute to attenuate, abaxial faces hispid to villous, densely gland-dotted (at least toward apices).
15–25, lanceolate to lance-ovate, 6–19 × 0.7–4 mm (equaling or slightly surpassing discs), (margins ciliate) apices (spreading to recurved) acuminate, abaxial faces usually glabrate or sparsely hispid.
1–5.
1–5.
5–7 mm, glabrate;
pappi of 2 aristate scales 2.4–2.6 mm.
3–4 mm, glabrous;
pappi of 2 lanceolate scales 2.5–2.9 mm.
9–11 mm, 3-toothed (gland-dotted).
8–9 mm, apices 3-toothed (apices glabrous).
= 102.
= 34.
Helianthus resinosus
Helianthus paradoxus
Consistent with its epithet, Helianthus resinosus has abundant subsessile glandular hairs (“resin dots”) on its leaves, phyllaries, paleae, and ray laminae. It intergrades and has been reported to hybridize with H. tuberosus. It is cultivated and usually sold under the long-misapplied name H. tomentosus Michaux.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Helianthus paradoxus is listed by the U.S. Fish and Wildlife Service as an endangered species and is in the Center for Plant Conservation’s National Collection of Endangered Plants. It is of hybrid origin; the parents are H. annuus and H. petiolaris (L. H. Rieseberg et al. 1990). It occupies a different habitat type than either parent (H. annuus usually on clay-based mesic soils and H. petiolaris usually on dry, sandy soils).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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