Distribution: Very limited distribution in Washington along eastern border with Idaho; widely distributed throughout northern half of North America from Alaska to Newfoundland.
Habitat: Wetlands, lake margins, and riparian zones.
Flowers: May-July
Origin: Native
Growth Duration: Perennial
Conservation Status: Not of concern
Pollination: Beetles
Herbaceous perennials; rhizomes branched, creeping horizontally at or near surface; emits distinctive and pleasant odor when bruised or broken.
Leaves bright green, basally white with pink or red, sword-shaped; venation parallel along length of blade, prominent veins 2-6; swelling in center evident in cross section, tapering toward both ends; vegetative leaves to nearly 1.5 m, sheathing base 18-52 cm or more, distal portion of leaf generally 31-89 cm long and 0.3-1.2 cm broad, margins entire; sympodial leaf typically 57-148 cm long, usually equal to or slightly longer than vegetative leaves, sheathing base 25-75 cm long, distal portion 28-78 cm long and 0.3-1.3 cm broad.
Inflorescence a solitary spadix, from 3-angled axis, spadices 3.3-7.4 cm long and 4.7-10 mm broad during flowering period, 3.5-8 cm long and 7-18.2 mm broad when in fruit, nearly cylindric, tapering, apex obtuse; distal sympodial leaf extending beyond spadix; true spathe absent; flowers 2-3 mm; tepals 6, light brown; stamens 6, distinct; anthers yellow, turning inward toward flower center; pollen grains usually deeply staining in aniline blue; ovaries 1, green, usually 3-chambered, sessile; stigmas sessile, minute.
Berries, shaped like upside down pyramids, 4-6 mm; seeds usually 6, tan, slenderly oblong to obovate, 3-4 mm.
PNW Herbaria: Specimen records of Acorus americanus in the Consortium of Pacific Northwest Herbaria database
WA Flora Checklist: Acorus americanus checklist entry
OregonFlora: Acorus americanus information
E-Flora BC: Acorus americanus atlas page
CalPhotos: Acorus americanus photos