Perennial herb 15 cm - 0.9 m tall Leaves: usually two, long-stalked, with three leaflets (rarely five). The leaflets are more or less stalkless, to 30 cm long and 20 cm wide, with the terminal leaflet elliptic to broadly egg-shaped and the lateral leaflets usually asymmetrical and sometimes lobed or divided. Lower leaf surface covered with a whitish waxy coating (glaucous). Inflorescence: of many tiny flowers borne tightly clustered on the bottom half of a spike with a very fleshy axis (spadix), with male flowers above female flowers. The spadix yellow, 3 - 9 cm long, and club-shaped (rarely cylindric) with a blunt tip. The leaf-like sheath (spathe) surrounding the inflorescence forms a green tube sometimes marked with purple stripes, having a rim 4.5 - 9 mm wide, and expanding near the tip to form a long tapering hood over the inflorescence. Fruit: a 6 - 15 mm long cluster of nearly spherical red berries, each with one to three seeds reaching 3 - 5 mm across.
Similar species: Arisaema triphyllum ssp. stewardsonii is distinguished from Arisaema triphyllum ssp. triphyllum by having a glossy lower leaf surface, a 1 -3 mm wide spathe rim, a green spathe hood with white or purple stripes, and a usually cylindric spadix tip. It is limited to swamps, floodplains and other moist areas, and its range in the Chicago Region appears to be limited to LaPorte County, Indiana.
Flowering: mid April to mid July
Habitat and ecology: Common in rich woodlands.
Occurence in the Chicago region: native
Etymology: Arisaema comes from the Greek words aron, meaning Arum, and haima, meaning blood, referring to the blotchy red leaf color of some species. Triphyllum means three-leaved.