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.
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
Martin and Hutchins 1980, Welsh et al. 1993, FNA 2000
Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Perennial from fibrous roots, 20-90 cm tall, leaves all basal but emersed. Leaves: Basal, ascending or erect, blades ovate to elliptic, cuneate to rounded or cordate at base, blade 4-17 cm long and 2-8 cm wide, shorter than inflorescence, blade on long petiole 2.5-30 cm long, sheathing. Flowers: Pyramidal compound panicle terminal on erect stiff scape, bracteate and longer than leaves, the floral bracts ovate, papery, 2-3 mm long with pedicels ascending to erect, 0.5-4 cm long, sepals greenish, 3-4 mm long, rounded ovate, broadly scarious margined, persistent; petals white, 3-6 mm long, 6 stamens, 10-22 pistils, in a single whorl, usually straight style. Fruits: Achene about 3 mm long. Ecology: Found in marshy areas, open water, wet meadows and mud flats from 4,000-8,000 ft (1219-2438 m); flowers June-August. Distribution: Ranges from the Sky Islands of Arizona north along the Mogollon rim, up through the Rockies to the Dakotas and into Canada. Notes: Distinguished from other Alisma by the wider leaf blades and the broadly scarious margins on the sepals, along with the flowers that are about 1 cm in diameter. Ethnobotany: Unknown Etymology: Alisma is from Greek name for a water plant, while triviale means common or ordinary. Synonyms: Alisma brevipes, Alisma plantago-aquatica subsp. brevipes, Alisma plantago-aquatica var. americanum, Alisma plantago-aquatica var. brevipes Editor: SBuckley, 2010
Rhizome 1-2 cm thick; lvs usually long-petioled, the blade elliptic to broadly ovate, rounded to subcordate at base, 3-18 נ2-12 cm, 1.5-2.5(-2.7) times as long as wide; scape 1-10 dm; pedicels in whorls of 3-10; sep obtuse, 2-3 mm; pet white, 3.8-4.5 נ3.0-3.9 mm, half again as long as the sep; style short, 0.4-0.6 mm, the stigmatic part ±curved; achenes 15-23, 1.8-3.0 mm, ordinarily with a median dorsal groove, rarely with 2 grooves as in no. 3 [Alisma gramineum Lej.]; 2n=28. Marshes, ponds, and streams; N.S. and e. Que. to Pa., w. to s. B.C., Mo., N.M., and Calif. June-Sept. (A. brevipes; A. plantago-aquatica var. americanum)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Found only in our northern counties with the habitat of the preceding species. This species was unknown to me until I studied my specimens. It is probable that now since I know it, I could find it in more of our northern counties. I have specimens from Lake, Elkhart, and Newton Counties. This is the boreal representative of the genus.
Indiana Coefficient of Conservatism: C = 2
Wetland Indicator Status: OBL
Diagnostic Traits: Similar to Alisma subcordata but with larger flowers and fruits. Larger flowers >4 mm broad; sepals 3-6 mm; achenes >2.2 mm.