Resindot Sunflower

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.

Perennials, 100–300 cm (rhi-zomatous). Stems (often reddish or purplish) erect, hirsute or villous. Leaves 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. Heads 1–5. Peduncles 1–3 cm. Involucres hemispheric, 15–27 mm diam. Phyllaries 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). Paleae 9–11 mm, 3-toothed (gland-dotted). Ray florets 10–20; laminae (often light yellow) 18–30 mm. Disc florets 90+; corollas 8–8.5 mm, lobes yellow; anthers dark, appendages dark. Cypselae 5–7 mm, glabrate; pappi of 2 aristate scales 2.4–2.6 mm. 2n = 102.

Helianthus resinosus is a North American species of sunflower known by the common name resindot sunflower. It is native to the southeastern United States from Mississippi to North Carolina.

Helianthus resinosus grows in open swamps and meadows, and along roadsides. It is an perennial herb up to 300 cm (10 feet) tall, spreading by means of underground rhizomes. Leaves are up to 20 cm (8 inches) long, dotted with visible resin glands embedded in the leaves. One plant usually produces 1-5 flower heads, each containing 10-20 yellow ray florets surrounding 90 or more yellow disc florets.