Jamesia americana var. macrocalyx (Small) Engl.

Bark exfoliating tardily in gray strips or strings. Leaves: petiole 2–8(–12) mm; blade ovate to obovate or rhombic, (0.7–)1.2–3(–3.9) × (0.5–)0.8–1.8(–3.2) cm, margins dentate, teeth (5–)11–21(–27). Inflorescences usually (2–)3–9(–13)-flowered, sometimes flowers solitary. Flowers: sepals lanceolate to triangular-ovate, (2.5–)3–7 mm; petals white or pinkish white, (6.5–)7.5–11.5 mm; styles 4–6.7 mm.