Erigeron mariposanus Congdon

Erigeron mariposanus is closely similar to E. aequifolius.

Perennials, 15–28 cm; taprooted (root or caudex branches 1–4 cm, rhizomelike or caudexlike). Stems decumbent-ascending (distal branches spreading-ascending, axillary tufts of smaller leaves prominent at most nodes), sparsely to moderately strigose (hairs ascending-appressed), eglandular. Leaves cauline; blades oblanceolate, (25–)30–45 × (2–)5–8 mm, reduced near heads, margins entire, faces sparsely to moderately strigose, eglandular. Heads 1 or 2–4 (in loosely corymbiform arrays). Involucres mostly 4–5 × 8–12 mm. Phyllaries in 3–5 series, outer (midnerves prominently orange-resinous) sparsely strigose (hairs thin-based), eglandular (inner: margins broadly scarious, nearly winglike). Ray florets 18–22; corollas bluish, 5–8 mm, laminae sometimes coiling slightly at tips. Disc corollas 4–4.5 mm (throats slightly indurate, not inflated). Cypselae 2–2.4 mm, 2-nerved, faces sparsely strigose; pappi: outer of setae, inner of 28–32 bristles.

Erigeron mariposanus is a rare species of flowering plant in the family Asteraceae known by the common names foothill fleabane, Mariposa daisy, or Mariposa erigeron. It has been found only in a few locations in Mariposa County in California. Some sources say that it is now probably extinct.

Erigeron mariposanus is a perennial herb up to 28 centimeters (11 inches) tall, producing a woody taproot. The leaves and the stem are covered with hairs. The plant generally produces 1-4 flower heads per stem, each head with up to 22 blue ray florets surrounding numerous yellow disc florets.