Xanthisma viscidum (Wooton & Standl.) D. R. Morgan & R. L. Hartm.

Annuals, 25–60 cm; taproots 2–8+ cm. Stems 1, branched, moderately stout to stout, not wiry, stipitate-glandular. Leaves: basal usually withering by flowering; cauline evenly spaced, obovate to oblanceolate or oblong, 5–30 × 2–15 mm, markedly reduced distally, margins coarsely serrate to dentate, teeth 4–7 per side, entire, faces densely stipitate-glandular. Peduncles densely stipitate-glandular, usually ebracteate. Involucres hemispheric, 8–10 × 13–18 mm. Phyllaries in 5–7 series, linear, 2–7 mm, apices narrowly obtuse to acuminate, faces stipitate-glandular. Ray florets 14–18; corollas yellow, tubes 3–3.5 mm, laminae 2.8–3.5 × 1.5–2 mm. Disc florets 20–30+; corollas 5.5–6 mm. Cypselae oblong to narrowly ellipsoid, 2.3–2.7 mm, 18–22-nerved, sparsely whitish-silky; pappi tawny, 5–6 mm, mostly equal. 2n = 8.

Sideranthus viscidus Wooton & Standley, Contr. U.S. Natl. Herb. 16: 180. 1913; Haplopappus havardii Waterfall; H. viscidus (Wooton & Standley) S. F. Blake; Machaeranthera havardii (Waterfall) Shinners; M. viscida (Wooton & Standley) R. L. Hartman