Proc. Amer. Acad. Arts 13: 371. 1878,.
Plants: rhizomes proliferating underground. Flowering stems (30–)50–80(–130) cm. Basal leaves: petiole 5–22 cm; blade usually orbiculate-cordate, sometimes reniform, shallowly and indistinctly lobed, (3.5–)7–16 × (4–)9–18 cm, margins 2–3-times serrate. Cauline leaves: stipules 1–2 mm expansions of petiole base, fringed with brown hairs. Inflorescences ± pyramidal, (10–)15–25-flowered per primary branch. Pedicels densely stipitate-glandular. Flowers: hypanthium campanulate, free portion 1–2 mm, densely stipitate-glandular; sepals erect, triangular to lanceolate, 1.5–2 mm, apex acute; petals narrowly spatulate, 2–3 × 1 mm, shorter than or to 1.5 times as long as sepals, base tapered to claw, margins plane; nectary green; stamens 1.2–1.6 mm; ovary 2/3 inferior. Capsules ovoid, turbinate, or urceolate. Seeds usually black, tuberculate. 2n = 14.
Phenology: Flowering early-mid summer.
Habitat: Damp woodlands, margins of lakes, ponds, and watercourses, often on disturbed soil, trailsides, mudslides
Elevation: 800-2000 m
Calif., Mexico (Baja California).
The record of Boykinia rotundifolia from “Lower California” (Williamson, 20 July 1901, PH) is the only collection seen from Mexico. The species is occasionally grown in gardens.