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Northern Prairie Wildlife Research Center

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Aquatic and Wetland Vascular Plants of the Northern Great Plains

59. Araceae, the Arum Family

1. Acorus L. -- Sweet flag, calamus

1. Acorus calamus L.

Moderately tall, reedlike plant from stout rhizomes; fresh foliage and rhizomes sweetly fragrant when crushed. Leaves linear, acute-tipped, 5-15 dm long, 5-20 mm wide, rather tough and leathery, the margins scarious toward the base. Scape arising lateral to the leaves, tyigonous; spathe appearing as a leaflike extension of the scape, often as long as the scape itself, reaching about as high as the leaves; spadix protruding laterally from the juncture of the scape and spathe, erect or ascending, long-cylindric, 5-10 cm long, 5-10 mm thick at anthesis, to 20 mm thick in fruit. Flowers perfect, yellow or brownish, perianth of 6 chartaceous tepals, deciduous; pistil 2- or 3-carpellary. Fruit obpyramidal, hard and dry, 1- to 3-seeded. Jun--Jul. Bogs, marshes and stream margins; frequent in ne SD, otherwise rare and scattered from c and e ND to c and se NE; (Intro. from Europe and widely established in N.Amer. from N.S. and Que. to Alta., s to FL, TX, CO, n ID and WA; also Asia).

The distribution of A. calamus in the northern Great Plains probably reflects patterns of introduction from the east by eastern plains Indian tribes who used the plant for medicinal and religious purposes.

GIF- Species Photo/Drawing
GIF- Distribution Map

Map key

Return to Family -- Araceae - The Arum Family
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