General: Perennial, 30-60 cm tall; stems usually several, erect or ascending, slender; herbage villous; caudex thick, woody, simple to branched.

Leaves: Basal and cauline, alternate, pinnate, up to 40 cm long, leaflets numerous, inversely triangular, 4-8 mm long, the apex 3-lobed or 3-toothed; blades petiolate.

Flowers: Inflorescence a cyme, mostly 1-3 flowered, the flowers nodding, borne on long pedicels; hypanthium hemispheric; sepals erect at time of flowering, lanceolate, 7-13 mm long; petals narrowly to broadly elliptic, 8-15 mm long, white to pink; stamens numerous; flowers May-August.

Fruits: Achene.

Ecology: Rocky slopes, canyon bottoms, drainages, pinyon-juniper woodlands, ponderosa pine forests; 1500-2300 m (5000-7500 ft); Coconino and Yavapai counties; endemic to Arizona.

Notes: Ivesia arizonica (rock purpusia) is distinguished by having glandular-puberulent herbage; shorter basal leaves (6-15 cm long), with 3-4 pairs of lateral leaflets, these broadly ovate to orbicular; and yellow petals. It occurs peripherally within our range along rock outcrops, crevices, and hanging gardens, often on limestone. Ours is var. arizonica [=P. osterhoutii].

Editor: Springer et al. 2008