Agoseris grandiflora (Nutt.) Greene

Stems usually 0, rarely weakly de-veloped. Leaves erect to ascending; petioles often purplish, margins ciliate to tomentose; blades usually linear to oblanceolate, rarely spatulate, 10–40(–50) cm, margins usually dentate to lobed, or laciniately pinnatifid, rarely subentire, lobes 3–5 pairs, opposite to irregular, linear to lanceolate, usually antrorse, sometimes spreading; lobules often present, faces ± villous to canescent. Peduncles elongating after flowering, (15–)25–60(–96) cm in fruit, ± glabrate, or apically villous to tomentose, eglandular, sometimes bracteate. Involucres campanulate to hemispheric, 2–5 cm in fruit. Phyllaries in 4–5 series, green or medially rosy purple and/or spotted, subequal to unequal, margins occasionally dentate, ciliate or lanate, sometimes glabrous, faces glabrous or hairy, eglandular; outer subequal to or surpassing inner at flowering, spreading, adaxially tomentose; inner erect, greatly elongating after flowering. Receptacles epaleate. Florets 40–500; corollas yellow, tubes 4–7(–10) mm, ligules 3–7 × ca. 1 mm; anthers 1–3 mm. Cypselae 9–28 mm, bodies fusiform, 3–7 mm, beaks 9–21 mm, lengths mostly 3–4 times bodies; ribs ridged to subalate, rarely nerviform, straight, ± glabrous; pappus bristles in 2–3 series, 7–15 mm. 2n = 18.

Stylopappus grandiflorus Nuttall, Trans. Amer. Philos. Soc., n. s. 7: 432. 1841

Agoseris grandiflora is broadly distributed across the western portion of North America including California to Alaska and eastward to Idaho, Montana, Nevada and Utah. This flowering plant is found in a variety of habitats including frassland, scrub and woodland at elevations of less than 2000 meters.

Also known as Mountain dandelion, this perennial reaches a height of 25 to 100 centimeters. Leaves are linear to oblanceolate, acute to long-tapered. The inflorescence exhibits phyllaries that are lanceolate to ovate, often red-tinged, with tips prominent. There are many flowers per plant, manifesting yellow ligules. The fruit measures a characteristic size of 3.5 to 7.0 millimeters.

Agoseris grandiflora is a North American species of flowering plant in the family Asteraceae known by the common names California dandelion, bigflower agoseris, and grassland agoseris.

The plant is native to western North America from British Columbia to California to Utah, where it grows in many habitat types.