Viola deltoidea Yatabe.

Herbs perennial, glabrous. Rhizome short, densely noded, with long, slender roots. Stems usually several fasciculate, rarely solitary, erect or obliquely ascending, ca. 30 cm tall at anthesis, elongated after anthesis, to 100 cm tall, slender, glabrous, usually simple or sometimes branched. Basal leaves withered early; stipules of cauline leaves free, leaflike, narrowly lanceolate, large, 1.5-4 cm, subequaling or exceeding petioles, glabrous, margin subentire or usually irregularly 1-3-lobed in lower part, apex slightly obtuse or acute; petioles short, 1-3 cm, narrowly winged in upper part; blades of cauline leaves oblong-triangular, 1.5-7 × 1-2 cm, both surfaces glabrous, base nearly hastate, shallowly cordate, or subtruncate, margin remotely and shallowly crenate or subentire, apex ± acute or obtuse. Flowers bluish purple, small, long pedicellate; pedicels produced from cauline leaf axils, usually not exceeding leaves, 2-bracteolate at upper part; bracteoles linear, small. Sepals lanceolate or subulate, 4-4.5 mm, apex slightly acuminate, basal auricles very short, apex truncate and remotely crenate. Petals oblong-obovate, 7-8 mm, with brown glandular dots, margin slightly repand, lateral ones glabrous, anterior one shorter, ca. 7.5 mm (spur included), deep blue-purple striate; spur very short, ca. 2 mm, apex rounded, slightly exceeding basal auricles of sepals. Anthers ca. 1.8 mm, appendage of connectives ca. 1.2 mm, spur of 2 anterior stamens subtriangular, very short, only ca. 1 mm, apex obtuse. Ovary glabrous, with glandular dots; styles slightly slender at base, conspicuously geniculate forward, thicker in upper part; stigmas 2-lobed, lobes erect, thick, shortly beaked at base in between 2 lobes, with a conspicuous stigma hole at tip of beak. Capsule oblong, ca. 1 cm. Fl. Jul, fr. Aug-Sep. 2n = 24.

This species is very rare and possibly endangered.

Thickets and forests along riversides, moist grasslands; below 1200 m. Heilongjiang, Jilin, Nei Mongol [Japan, Korea, Russia].