Viscid Tansyaster

Annuals, 20–100 cm, herbaceous or suffrutescent. Leaf blades oblanceolate to oblong or oblong-lanceolate, mid-cauline (1–)4–15(–25) mm wide. Heads on short, sometimes bracteate peduncles, not surpassed by distal leaves. Involucres (4.5–)6–9 × 9–15(–20) mm. Phyllaries in 3–4 series, loose, strongly unequal, apices broadly spreading to squarrose, ca. 0.9–1 mm wide, herbaceous. Ray florets (13–)20–36; corollas 6–11(–14) mm. Disc florets: corolla tubes ± equaling limbs. 2n = 12.

Sideranthus annuus Rydberg, Bull. Torrey Bot. Club 31: 653. 1905; Haplopappus annuus (Rydberg) Cory; Machaeranthera annua (Rydberg) Shinners