General: Perennial, 20-80 cm tall; stem slender and solitary, attached below ground level to one or more tuberous roots.

Leaves: Basal and cauline, alternate, compound, ovate to lanceolate in outline, 5-20 cm long, mostly ternate (sometimes pinnate below); leaflets linear to narrowly lanceolate, 2-10 cm long, margins entire; petioles 3-10 cm long.

Flowers: Inflorescence of 4 or more terminal and axillary compound umbels per stem, with 5-20 unequal rays each 1-7 cm long; involucre absent, pedicels 3-10 mm long, subtending bractlets absent; calyx toothed; petals white; stamens white; stylopodium conic, styles generally less than 1 mm long; flowers July-August.

Fruits: Schizocarp, ovoid to oblong, 3-7 mm long, flattened dorsally, glabrous, lateral wings broad, dorsal wings variously broad to nearly absent.

Ecology: Moist meadows, open forests, mostly in ponderosa pine; 1800-3000 m (6500-10000 ft); Apache, Coconino, and Navajo counties; southwestern U.S.

Notes: Our specimens, as here described, belong to ssp. parishii. Perideridia gairdneri (Gardner's yampah), which occupies approximately the same range, is distinguished primarily by its pinnate leaves and fruits about as long as wide (vs. longer than wide in P. parishii). Perideridia parishii is a host plant for the anise swallowtail butterfly.

Editor: Springer et al. 2008