Arisaema sikokianum
Common Name: Japanese cobra lily 
Type: Herbaceous perennial
Family: Araceae
Native Range: Japan
Zone: 5 to 8
Height: 1.50 to 2.00 feet
Spread: 1.50 to 2.00 feet
Bloom Time: April to May
Bloom Description: Dark purple with white spadix
Sun: Part shade to full shade
Water: Medium to wet
Maintenance: Medium
Flower: Showy
Tolerate: Wet Soil


Best grown in humus-rich, moist but well-drained soils in part shade to full shade. Needs consistent moisture. Does poorly in heavy clay soils. Plant tubers about 3-4" deep. May be grown from seed, but may take 3-5 years before plant will flower.

Noteworthy Characteristics

Arisaema sikokianum is a tuberous woodland perennial that is native to Japan. It is closely related to the jack-in-the-pulpit that is native to eastern North America (Arisaema triphyllum). It typically grows to 18-24" tall. Each tuber produces a single stem containing a pair of 5-lobed leaves. From the center of the leaf stalks rises a flower in spring. Each flower consists of a hooded leafy bract called a spathe which envelops an upright flowering spike called a spadix. The spathe is dark purple on the outside and pure white on the inside with a colorful hood that features purple, dark green and white striping. The spadix is a pure white and enveloped by the spathe. Plants go dormant in summer after flowering, except hermaphroditic flowering plants will produce a cluster of red berries in mid to late summer which become visible as the spathe withers. Stalks, leaves, flowers and fruits give this plant a tropical aura. Roots contain calcium oxalate (same chemical as in Diffenbachia or dumb cane) and are poisonous.

This species is synonymous with and formerly known as Arisaema japonica.

Genus name comes from Greek words aris meaning "arum" and aima meaning "red", in reference to the red-blotched leaves found on some species.


No serious insect or disease problems.


Plant in groups. Best left undisturbed in shady woodland gardens, wild gardens or native plant areas.