Arnica gracilis

Rydberg

Bull. Torrey Bot. Club 24: 297. 1897.

Common names: Smallhead arnica
Endemic
Synonyms: Arnica latifolia var. gracilis (Rydberg) Cronquist
Treatment appears in FNA Volume 21. Treatment on page 376. Mentioned on page 368.

Plants 10–30 cm. Stems (often 5–10 in dense clumps) branched distally. Leaves 2–3 pairs, mostly cauline (basal leaves often persistent on sterile rosettes, similar to cauline leaves); petiolate (petioles narrowly to broadly winged, distal pair of leaves often reduced, connate-perfoliate); blades ovate to ovate-lanceolate, 2–6 × 1–3 cm, margins irregularly serrate to subentire, apices acute, faces: abaxial glandular, adaxial stipitate-glandular. Heads (1–)5–15. Involucres turbinate-campanulate. Phyllaries 10–16, ovate-lanceolate. Ray florets 5–12; corollas yellow. Disc florets: corollas yellow; anthers yellow. Cypselae black, 4.5–7 mm, hairy (hairs duplex) and stipitate-glandular; pappi white, bristles barbellate. 2n = 57, 76.


Phenology: Flowering Jul–Aug.
Habitat: Dry, exposed, rocky, alpine slopes, sometimes subalpine meadows
Elevation: 1200–2500 m

Distribution

V21-946-distribution-map.gif

Alta., B.C., Idaho, Mont., Oreg., Utah, Wash., Wyo.

Discussion

Selected References

None.

Lower Taxa

None.