Sagittaria latifolia (Broad-leaf Arrowhead)
|Also known as:||Common Arrowhead, Duck Potato|
|Family:||Alismataceae (Water Plantain)|
|Habitat:||part shade, sun; swamps, streams, wet ditches, shallow water|
|Bloom season:||July - September|
|Plant height:||1 to 4 feet|
|Wetland Indicator Status:||GP: OBL MW: OBL NCNE: OBL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Flowers are whorled in groups of 3 in a spike-like raceme up to 1 foot long. There are usually both male and female flowers on the same stem, but sometimes a stem has a single gender. Both genders are about 1 inch across with 3 broad white petals and 3 small pale green sepals behind the flower. Female flowers have a bulbous green center, covered in tiny carpels.
At the base of the whorl are 2 or 3 boat-shaped bracts that are 1/8 to 1/3 inch long and typically less than half as long as the flower stalks. The bracts shrivel up quickly, the brown, papery remains persisting through fruiting. A plant has 1 or more flowering stem, each with 3 to 9 whorls of flowers. The flowering stem may be taller or shorter than the basal leaves.
A rosette of basal leaves surrounds the flowering stems. Leaves are toothless, hairless and arrowhead shaped with the basal lobes at least half as long as, and usually up to a little longer than, the remainder of the blade. Leaves are up to 16 inches long but are usually about half that.
The width is highly variable. In shallow water or drier soil conditions leaves are broad, and narrow when the plant is submersed in deeper water. Leaf stalks are up to 2 feet long. Flowering stems and stalks are hairless.
Of the 6 Sagittaria species in Minnesota, Broad-leaf Arrowhead is the most common, found in wet ditches and the shallow waters of lakes, ponds and streams all across the state. All Arrowheads have similar white, 3-petaled flowers and long-stalked, basal leaves. Ways to distinguish them are the size and shape of the bracts at the base of the flower whorl, the size of (or absense of) the leaf basal lobes relative to the rest of the blade, and the angle of the beak on the seeds. Broad-leaf Arrowhead has the largest leaves of the MN species, the basal lobes are at least half as long, often as long as, the remainder of the blade, seed beaks are horizontal, and the boat-shaped bracts relatively short.
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- Broad-leaf Arrowhead plant, in a stream
- narrow-lobed plants in deeper water
- a colony of Broad-leaf Arrowhead
Photos by K. Chayka taken at Vadnais/Snail Lake and Battle Creek Regional Parks, Ramsey County, and Interstate State Park, Chisago County. Other photos courtesy Peter M. Dziuk.
Have you seen this plant in Minnesota, or have any other comments about it?