Roosevelt Dam Rockdaisy

Perityle saxicola occurs in the area of Tonto National Monument and Roosevelt Dam in central Arizona. The 2–3-pinnately dissected leaves with long-linear to flat-filiform lobes distinguish it from the similar P. gilensis with its broader leaf lobes.

Perennials or subshrubs, 20–40 cm; glabrate or puberulent. Leaves: petioles 10–30 mm; blades (2–)3-pinnate, 15–55 × 10–50 mm, lobes linear to flat-filiform, scarcely broadened distally. Heads borne singly or (2–4) in loose, corymbiform arrays, 7.5–10 × 10–14 mm. Peduncles 1–3 mm. Involucres broadly campanulate to hemispheric. Phyllaries 14–25, linear-lanceolate to lanceolate, 5–7 × 0.5–1 mm. Ray florets 10–17; corollas yellow, laminae oblong to oblong-ovate, 4–6 × 2–3.2 mm. Disc florets 75–200; corollas yellow, tubes 1–1.2 mm, throats narrowly tubular to narrowly funnelform, 2–2.5 mm, lobes ca. 0.7 mm. Cypselae narrowly oblanceolate to narrowly oblong-elliptic, 2.8–3.2 mm, margins notably calloused, sparsely short-hairy; pappi 0 or of 1(–2) bristles (2–)4–5 mm. 2n = 34.

Laphamia saxicola Eastwood, Proc. Calif. Acad. Sci., ser. 4, 20: 159. 1931

Perityle saxicola is a rare species of flowering plant in the aster family known by the common names Roosevelt Dam rockdaisy and Fish Creek rockdaisy. It is endemic to Arizona in the United States, where it occurs in Tonto National Monument near the Roosevelt Dam.

This perennial herb or subshrub grows 20 to 40 centimeters tall. The narrow-lobed leaf blades are borne on petioles up to 3 centimeters long. The flower heads contain several yellow ray florets each about half a centimeter long and many yellow disc florets in the middle.

The plant grows in dry, rocky canyon habitat, anchoring in rock cracks and crevices.

Threats to the survival of the plant include blasting and aphid damage.