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See list of 2 species in this genus

Acorus was traditionally placed in the Araceae. This erroneous placement of the genus was partly due to incorrect interpretation of the distal portion of the sympodial leaf—a structure that had been considered to be a spathe. Two species are now recognized to occur in our area. Acorus calamus is a sterile triploid that has been introduced from Europe. Acorus americanus is a fertile diploid native to North America. References: Haines (2000a), Thompson (2000a).

  • 1a. Secondary veins of dried leaf blades up to ca. 0.5 times the width of the midvein (i.e., leaves with 1 prominent midvein and numerous finer, secondary veins); fruits not produced; sympodial leaf often as tall as or shorter than the vegetative leaves; vegetative leaves (5–) 10–20 mm wide, often crisped or undulate; flowers 3–4 mm long
  • 1b. One or more of the secondary veins of dried leaf blades ca. 0.75–1 times as wide as the midvein (i.e., leaves with 2–6 prominent veins as well as numerous finer, secondary veins); fruit produced, an obpyramidal berry; sympodial leaf usually as tall as or taller than vegetative leaves; vegetative leaves 3–10 (–12) mm wide, not crisped, entire; flowers 2–3 mm long

 Show photos of:   Each photo represents one species in this genus.