Helianthus carnosus Small

Helianthus carnosus is distinctive in morphology and is known from relatively few counties in northeastern Florida.

Perennials, 10–60 cm, (with crown buds). Stems erect, (unbranched) glabrous, eglandular. Leaves 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). Heads 1(–3). Peduncles 5–10 cm. Involucres broadly hemispheric, 17–25 mm diam. Phyllaries (green with purple veins) 25–30, ovate to lance-ovate, 8–16 × 3–5 mm, apices acuminate, abaxial faces usually glabrous, sometimes puberulent. Paleae 8–9 mm, 3-toothed (middle teeth long-acuminate). Ray florets 12–17; laminae 20–40 mm, (abaxial faces not gland-dotted) . Disc florets 100+; corollas 6–6.5 mm, lobes yellow; anthers dark, appendages yellowish or dark. Cypselae 3 mm, glabrous; pappi of 2 aristate scales 1.5–2 mm plus 2–4 erose scales 0.3–0.6 mm. 2n = 34.

Helianthus carnosus is a rare North American species of sunflower known by the common name lakeside sunflower. It is found only in the northeastern part of the state of Florida in the United States.

Helianthus carnosus is a perennial herb up to 60 cm (2 feet) tall. Most of the leaves are close to the base of the stem, each leaf hairless, evergreen, up to 25 cm (10 inches) long. There are only a few small leaves on the stem, the only species in Florida with that characteristic. One plant usually produces only one flower head, rarely 2 or 3. Each head has with 12-17 yellow ray florets surrounding 100 or more yellow disc florets. The plant grows in wet sites in prairies in coastal beach sands at low elevations.

Helianthus carnosus là một loài thực vật có hoa trong họ Cúc. Loài này được Small mô tả khoa học đầu tiên năm 1902.