Flower:

Flowers are whorled in groups of 3 in a spike-like raceme at the top of a naked stem. There are usually both male and female flowers on the same stem, with whorls of males above the females. Both genders are ½ to ¾ inch across with 3 broad, paddle-shaped, white petals and 3 small, pale green to brownish sepals behind the flower. Male flowers have a group of yellow stamens in the center. Female flowers have a bulbous green center, covered in tiny carpels.

At the base of the whorl are 2 or 3 narrowly triangular to lance-shaped bracts that are sharply pointed at the tip, and ¼ to 1½ inches long, often nearly 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 stems, each with 2 to 10 whorls of flowers. The flowering stem may be taller or shorter than the basal leaves and is sometimes branched at the lowest whorl of flowers.

Leaves and stems:

A rosette of toothless, hairless basal leaves surrounds the flowering stems. Emersed leaves are up to 3½ inches long, to 2 inches wide, typically arrowhead shaped, with the basal lobes shorter than the remainder of the blade, or sometimes egg to somewhat heart-shaped, without the basal lobes. Emersed leaves are long stalked and may be erect, rising above the water, but often floating on the surface.

Submersed leaves are ribbon-like, flat and linear with sharply pointed tips and may grow to 18 inches long in deeper water. Flowering stems and leaf stalks are hairless.

Fruit:

Fruit is a globular head, about ½ inch in diameter, of beaked seeds. The beak is erect at the top of the seed

Notes:

Of the 6 Sagittaria species in Minnesota, Arum-leaved Arrowhead most closely resembles Broad-leaved Arrowhead (Sagittaria latifolia), but in miniature. The arrowhead-shaped leaves differ with S. latifolia having basal lobes that are usually about as long as the remainder of the blade and the seeds have a horizontal beak, where S. cuneata has shorter lobes and an erect beak. This is the predominant Sagittaria species in drainage ditches in western Minnesota and the Dakotas.