Arizona sunflower

Perennials, 20–30 cm (roots creeping). Stems erect to ascending, glabrous (glaucous). Leaves cauline; opposite; sessile; blades (bluish green) lanceolate, 2–7 × 0.5–1.3 cm, bases cuneate, margins entire (undulate), faces glabrous (glaucous). Heads 1–7. Peduncles 2–7.5 cm. Involucres hemispheric, 9–18 mm diam. Phyllaries 16–19, lance-ovate, 3.5–7 × 2–2.8 mm, (margins ciliate) apices acute, abaxial faces glabrate, sparingly gland-dotted. Paleae 5.5–6.5 mm, 3-toothed (apices acute, gland-dotted). Ray florets 10–14; laminae 7–9 mm. Disc florets 30+; corollas 3–3.5 mm, lobes yellow; anthers reddish brown, appendages brownish. Cypselae 2.8–3.2 mm, glabrous; pappi of 2 deltate, erose scales 1–1.7 mm. 2n = 34, 51.

Flowering summer–fall. Open pine woodlands; 1200–2100 m; Ariz., N.Mex.

Helianthus arizonensis is morphologically similar to the polyploid H. ciliaris; H. arizonensis is diploid (or triploid) and has entirely yellow disc corollas. It is known from relatively few sites.