Cardamine arakiana Koidz, Acta Phytotax. Geobot. 5: 119 (1936). TYPE:

Herbs, perennial. Rhizomes slightly thickened. Stems (10–)15–35(–42) cm; erect pubescent or rarely glabrous, usually branched above. Basal leaves simple, trifoliolate or rarely 5-foliolate, 6–17 cm; blade or terminal leaflet orbicular- or cordate-reniform, 1.3–4.5(–5.5) cm, 1.5–5.5(–6.5) mm wide, base cordate, margin repand or crenate, apex rounded; lateral leaflets suborbicular, 0.5–1 cm, 0.5–1.3 mm wide, base truncate to cordate, margin crenate; cauline leaves trifoliolate or rarely 5-foliolate, 2.5–15 cm, adaxially glabrous, pubescent adaxially; terminal leaflet ovate to suborbicular, 1–2.5 cm, 1–3 cm wide, base cordate to obtuse, margin crenate; lateral leaflets elliptic, ovate, or orbicular, 0.5–2.5 cm, 0.3–2 cm wide, usually petiolulate. Racemes ebracteate, 2–10 cm in fruit; fruiting pedicels 1–2 cm, ascending. Sepals 2–2.5 mm, ca. 1 mm wide, sparsely pubescent; petals white, 5–6 mm, 2–3 mm wide; filaments 2–3 mm. Fruits linear, 2.5–4 cm, ca. 1 mm wide, glabrous; style 2–3 mm. Seeds 1.5–2 mm. 2n = 32.

Flowering: Mar–Apr.

Habitat: Grassy silty-clay forest floor, forest margins in low mountains.

Distribution: Japan (Honshu).