Alisma triviale Pursh  
Family: Alismataceae
northern water plantain,  more...
[Alisma brevipes Greene,  more]
Alisma triviale image
Herbs, to 1 m. Leaves emersed, petiolate; blade linear-lanceolate to broadly elliptic or oval, to 35 ´ 3--12 cm. Inflorescences to 1 m. Flowers chasmogamous; sepals 3--6 mm; petals white, 3.5--6 mm, margins ± erose, apex obtuse; anthers ovoid, 0.6--1 mm; style ± curved, 0.4--0.6 mm, equal to ovary length. Fruiting heads 4.1--7 mm diam; achenes ovoid, 2.1--3 mm, abaxial keel broadly rounded with 1 median abaxial groove, beak erect or nearly erect. 2n = 28. Flowering spring--fall. Shallow muddy ponds, stream margins, marshes, and ditches; 0--2000 m; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask.; Alaska, Ariz., Calif., Colo., Conn., Idaho, Ill., Ind., Iowa, Kans., Maine, Mass., Mich., Minn., Mont., Nebr., Nev., N.H., N.Mex., N.Y., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.Dak., Utah, Vt., Wash., Wis., Wyo.; n Mexico. I have seen no specimens from West Virginia, but although the species is to be expected there.

Perennial aquatic herb to 1 m tall Leaves: emersed, long- and triangular-stalked, 3 - 18 cm long, 2 - 12 cm wide, linear to broadly elliptic or oval with a rounded to slightly heart-shaped base. Inflorescence: loosely branched (panicle) on a stalk 10 cm to 1 m long. Flowers: arranged in whorls of three to ten; sepals 2 - 3 mm long; petals (three) white, 3.5 - 6 mm long, tip rounded, margin may be slightly unevenly cut. Fruit: a cluster of fifteen to 23 achenes arranged in a circle (4.1 - 7 mm across). Each achene is egg-shaped, 1.8 - 3 mm long, with an erect to slightly angled beak and a rounded outer edge with a single groove.

Similar species: The similar Alisma subcordatum has flowers 2 - 4 mm across and achenes up to 2 mm long.

Flowering: early July to late September

Habitat and ecology: This species grows in marshes, shallow water, and ditches. It is less common than Alisma subcordatum and has a more northern distribution.

Occurence in the Chicago region: native

Etymology: Alisma is the classical Greek name for the water plantain. Triviale means "common."

Author: The Morton Arboretum

Alisma triviale image
Alisma triviale image
Alisma triviale image
Max Licher  
Alisma triviale image
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