Japan Flora: Pseudostem 20-35 cm. long, from a depressed- globose tuber bearing small tubers on the sides; leaf solitary, the petiole terete, nearly erect, 10-25 cm. long, the blade palmately 5-foIiolate, the rachis not developed, the leaflets obovate or ovate, 10-15 cm. long, 4-7 cm. wide, abruptly short-acuminate; peduncle 2-5 cm. long; spathe green with longitudinal white stripes or dark purple (forma atropurpureum T. Koyama), somewhat auriculate on the upper margin of the tube, the blade ovate, 5-6 cm. long, long-acuminate, obliquely ascend­ing, scarcely narrowed at base; spadix-appendage cylindric, thickened and truncate at base.  May-June. Woods.

Hok­kaido, Honshu, Kyushu. Korea and Sakhalin.

Arisaema hakonecola Nakai  is poorly known and may be the same as A, robustum, differing allegedly in the larger spathe with a uniformly dark purple blade arching over the spadix, and a very stout appendage of the spadix. Honshu (Hakone).