Convolvulus peirsonii Abrams in L. Abrams and R. S. Ferris, Ill. Fl. Pacific States 3: 387, fig. 3866. 1951 (as piersonii)

Perennials, rhizomatous. Herb­age glabrous, sometimes glau­cous. Stems decumbent, pro­cumbent, or ± twining-climbing, 15–40 cm. Leaves: blade narrowly triangular-hastate, to 20 mm, base lobed, lobes ± oblong to rhombic, 1-pointed, basal sinus quadrate to rounded. Bracts immediately subtending, or to 3 mm distant from, sepals, elliptic to broadly elliptic-oblong, 3–7 × 2.5–4 mm, margins entire. Flowers: sepals 9–13 mm; corolla white, 25–40 mm.

Flowering May–Jun. Chaparral, desert scrub, dry, rocky, gravelly slopes; 300–1600 m; Calif.

Calystegia peirsonii intergrades with C. longipes and C. macrostegia subspp. cyclostegia and intermedia.