Plant: shrub or subshrub; to 0.5 m tall, often less; current growth often sparsely branched Leaves: sessile, 1-3(-4) cm long, 0.2-1 cm wide, those of branches and main axis similar in size; blade linear to narrowly oblong or elliptic; margin entire, occasionally few-toothed INFLORESCENCE: RACEMES to 10(-20) cm long, 1-2 cm wide. OUTER BRACT 5-11 mm long, 2-7 mm wide; margin crenate to entire; apex obtuse Flowers: petals free, 2-5.5 mm long; stamens 3-7 mm long Fruit: ACHENE 2-4 mm long; SEED subapical; testa non-sculptured; endosperm lacking Misc: Rocky canyons to sandy washes and dunes; to ca. 1000 m (3200 ft); (Dec)Mar-Jun REFERENCES: Christy, Charlotte M. 1998. Loasaceae. J. Ariz. - Nev. Acad. Sci. 30(2): 96.

Christy 1998, Jepson 2012, Kearney and Peebles 1969

Duration: Perennial Nativity: Native Lifeform: Subshrub General: Herbaceous or shrubby perennials, to 50 cm tall, stems current growth often sparsely branched, herbage with minutely barbed hairs. Leaves: Alternate, sessile or nearly so, linear to narrowly oblanceolate, to 25 mm long and 3-6 mm wide, with obtuse to acute tips, margins entire to irregularly toothed, surfaces with barbed hairs. Flowers: White, with 5 free petals 2-5.5 mm long, sepals 5, stamens slightly exserted, 3-7 mm long, styles 3-6 mm long, ovary inferior, flowers with 3 subtending ovate-cordate outer bracts 5-11 mm long, 2-7 mm wide the outer larger than the inner, with obtuse tips and crenate to entire margins, densely soft-pubescent, flowers borne in racemes to 20 cm long and 1-2 cm wide on pedicels 1-2 mm long. Fruits: Erect, appressed, ovoid, papery, achenes 2-4 mm long. Seeds 1 per achene, fusiform, 1.5-2.5 mm long, with smooth surfaces, somewhat visible through the outer surface of the achenes. Ecology: Found in rocky canyons, sandy washes and dunes, to 3,500 ft (1067 m); flowering December-June. Distribution: Arizona, California; Mexico. Notes: This small plant tends to grow in dense clumps, with thick masses of small leaves and tightly bunched infloresences, the fruits with wide, papery margins and noticable endosperm. Look for it in Yuma county and southwestern Arizona according to Kearney and Peebles. Ethnobotany: Unknown. Synonyms: None Editor: LCrumbacher2012 Etymology: Petalonyx comes from the Greek petalon, "petal," and onyx, "claw," thus claw-petalled, and linearis means linear, parallel-sided.