7a. Physaria argyraea (A. Gray) O’Kane & Al-Shehbaz subsp. argyraea
Perennials; caudex simple or branched, (woody); ± densely pubescent, trichomes (sessile or short-stalked), few- to several- rayed, rays fused at base, (smooth or finely tuberculate). Stems simple or several from base, prostrate and spreading to decumbent or erect, 0.5-4(-7) dm. Basal leaves (usually shed early); blade oblanceolate, 2-6(-8) cm, margins entire or pinnatifid. Cauline leaves (densely overlapping, often appressed, erect; petiolate); blade elliptic or obovate to rhombic, 0.5-4.5 cm, margins entire or sinuate or remotely dentate, (apex usually acute). Racemes loose. Fruiting pedicels (spreading to erect or occasionally slightly recurved, sigmoid, straight, or slightly curved), 15-40 mm. Flowers: sepals linear to oblong or elliptic, (3-)4-8 mm, (median pair thickened apically, cucullate); petals (orange or yellow, rarely fading purplish, claw often orange), spatulate or obovate to obdeltate, (narrowing to relatively short claw), 4.5-8.5(-11) mm. Fruits subglobose to broadly ellipsoid, slightly compressed (or terete), 4-8 mm; valves (not retaining seeds after dehiscence), glabrous throughout; replum as wide as or wider than fruit; ovules 16-32 per ovary; style 1.5-5.5 mm. Seeds flattened, (sometimes narrowly margined).
Flowering Feb-May(-Jun). Sandy granite- or, usually, limestone-derived soils; 0-800 m; Tex.; n Mexico (Coahuila, Nuevo León).
Subspecies argyraea differs from subsp. diffusa (Rollins) O’Kane & Al-Shehbaz of the Sierra Madre Oriental of Mexico in being herbaceous (rather than at least somewhat woody throughout) and having decumbent to erect (rather than prostrate) stems.