Leaf blades coriaceous, 20-70 × 15-50 mm. Phyllaries 7-10 mm. Ray laminae 3-5(-7) mm. Disc corollas 9-11 mm. Cypselae 5-6 mm. 2n = 24. Flowering spring-late summer. Hillsides, canyons, among rocks; 800-1600 m; Ariz.; Mexico (Chihuahua, Sonora).
FNA 2006, Kearney and Peebles 1969
Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Herbaceous perennials, to 1 m tall, branching, herbage glabrous, glaucous. Leaves: Opposite, leathery, round-ovate, obtuse at the tips, margins toothed, base subcordate, borne on very short petioles (appearing sessile). Flowers: Heads small, radiate, rays white, 1-5, disk flowers hermaphrodite, sterile, anthers green, receptacles chaffy, involucres cylindric, of few, green, thin phyllaries 7-10 mm long, these equal, heads borne in terminal cymose clusters. Fruits: Achenes oblong 5-6 mm long. Pappus absent. Ecology: Found in canyons, hillsides, and among rocks from 3,000-5,000 ft (914-1524 m); flowering February-September. Distribution: Arizona, Mexico. Notes: This appears to be the only species of this genus in Arizona. Ethnobotany: Unknown Etymology: Guardiola is thought to be of Italian origins, but uncertain, while platyphylla means broad leaved. Synonyms: None Editor: LCrumbacher 2011