柳叶向日葵

Helianthus salicifolius is found chiefly in the region of the Ozark Plateau. It is cultivated and may occasionally escape. It was recorded from a single site in Chicago, Illinois, where it has now been extirpated.

Perennials, 150–250+ cm (rhi-zomatous). Stems (green or purplish) erect, glabrous (glaucous). Leaves cauline; alternate; sessile or subsessile; blades linear to lance-linear, 8–21 × 0.2–1.2 cm, bases ± attenuate, margins slightly serrulate to subentire (flat), abaxial faces glabrate, gland-dotted. Heads 6–15+. Peduncles 2–6 cm. Involucres campanulate, 10–18 mm diam. Phyllaries 40–50, linear to lance-linear, 12–20 × 1.8–2 mm, (margins ciliate) apices long-attenuate, abaxial faces glabrous or glabrate, not gland-dotted. Paleae 8–10 mm, entire or weakly 3-toothed (apices greenish, ± hirsute). Ray florets 10–20; laminae 28–35 mm (apices often bifid). Disc florets 50+; corollas 5.5–6 mm, lobes reddish; anthers dark, appendages dark (style branches yellow). Cypselae 4–6 mm, glabrous; pappi of 2 aristate scales 3–3.6 mm plus 2–8 lacerate scales 0.3–0.5 mm. 2n = 34.

Helianthus filiformis Small

Helianthus salicifolius is a North American species of sunflower known by the common name willowleaf sunflower. It is native to the central United States, primarily in the Great Plains and Ozark Plateau (states of Missouri, Kansas, Oklahoma, and Texas). There are a few reports of scattered populations in the Northeast and Midwest parts of the country, but these appear to be escapes from cultivation.

Helianthus salicifolius grows in limestone prairies. It is a perennial herbaceous plant up to 2.5 m (8.2 ft) tall, spreading by means of underground rhizomes. The leaves are long but very narrow, up to 21 cm (8.3 in) long, but rarely more than 1.2 cm (half an inch) wide. One plant usually produces 6-15 flower heads, each containing 10-20 yellow ray florets surrounding 50 or more red disc florets.