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Alisma subcordatum - American water plantain

Scientific Family
Alismataceae
Synonyms
Alisma plantago-aquatica ssp. subcordatum , Alisma plantago-aquatica L. var. parviflorum
Plant type
Forbs and Subshrubs
Origin
Native
Lifecycle
Perennial
Height
To 2 feet
Riparian
Yes

Aquatic perennial found in shallow water with erect or floating leaves that are oval or elliptic and sharply pointed at the leaf apex (acute). Any leaves that form underwater are weak and quick to rot; they rarely remain on adult plants.

Fibrous rooted, perennial forb that grows in shallow water; white flowers are borne in whorls on many branched flower stalks; style shorter than or (equal to) ovary, anthers rounded; oval leaf blades held above the water or float on it.

Habitat

Shallow ponds, stream margins, marshes, and ditches.

Plant Community
Riparian
Low elevation
100
High elevation
4900

Flower Characteristics

Bisexual, with 1/16 to 1/8 inch long sepals; 3 white petals are 1/16 to 1/8 inch long with a long pointed tip and slightly unevenly cut margins. Flowers are in a loosely branched (panicle) stalk.

Flower color
White
Flower shape
Regular
Tubular
No
First bloom month
July
Last bloom month
September
Flower clusters
Elongated

Leaf and Stem Characteristics

Leaves rise above the surface (rarely floating), to 7 inches long and 4-3/4 inches wide, egg-shaped to elliptic; stems triangular-shaped.

Leaf type
Simple
Leaf color
Green
Leaf shape
Round or oval
Leaf margin
Smooth
Leaf attachment
Alternate & Opposite
Leaves clasp
No
Leaf hairs
None
Spines
No

Fruit and Seed Characteristics

Cluster of achenes (small 1-seeded dry fruit that does not split open) 1/16 to 1/4 inch in diameter. Each achene has an ascending prolonged tip, is about 1/16 inch long, and has a rounded outer edge with a single groove.

Fruit type
Achene