Helianthus filiformis Small

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.

Flowering late summer–fall. Limestone prairies; 100–300 m; Kans., Mo., Nebr., Okla., Tex.

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.