Annuals, biennials, or short-lived perennials, (subshrubs in var. ziegleri). Stems, branches, and peduncles glabrous, puberulent, or canescent, sometimes also stipitate-glandular or gland-dotted. Leaf blades linear-lanceolate to linear or linear-oblanceolate (ovate to obovate in var. leucanthemifolia), mid 10–60 × 1.5–6(–8) mm, margins entire to irregularly dentate or serrate, faces glabrous, puberulent, or canescent, sometimes sparsely stipitate-glandular; distal bases not clasping or slightly clasping (clasping in var. leucanthemifolia). Involucres campanulate or turbinate. Phyllaries in 3–10 series, appressed, spreading, or reflexed, indurate bases usually glabrous, apices acute to acuminate, 1–3 mm, herbaceous, faces glabrous (indurate bases, sometimes foliaceous parts) or hairy (only foliaceous parts), sometimes stipitate-glandular. Receptacles 2.5–5 mm diam. Ray florets pistillate and fertile, or sterile or 0 (in var. shastensis); laminae white, blue, or purple, 6–12 × 1–3 mm. Disc florets: corollas 4–6(–7) mm. Cypselae glabrous or moderately appressed-hairy.
