Northern Prairie Wildlife Research Center
Northeast Wetland Flora
Field Office Guide to Plant Species
Myriophyllum heterophyllum Michx.
- Family: Water-milfoil (Haloragaceae)
- Flowering: June-September
- Field Marks: All the leaves of this species are whorled, the fruits have a pair of ridges down
their otherwise rounded back, the leaves and bracts that protrude above the water are
lanceolate to elliptic, and the 4 petals are up to 1/6 inch long.
- Habitat: Ponds, streams, shallow water.
- Habit: Aquatic perennial.
- Stems: Rather stout, smooth, branched.
- Leaves: All in whorls, the submersed ones pinnately divided, up to 2 1/2 inches long, with 6-12 pairs of segments, the emersed ones lanceolate to spatulate, up to 1/4 inch wide, with or without teeth along the edges.
- Flowers: Crowded in spikes, the male usually in the upper part of the spike, the female in the lower; each spike up to 12 inches long; flowers subtended by ovate, toothed bracteoles up to 1/24 inch long.
- Sepals: 0.
- Petals: 4 (at least in the male flowers), free from each other, up to 1/6 inch long, usually absent in the female flowers.
- Stamens: 4.
- Pistils: Ovary superior, 4-lobed, smooth.
- Fruits: Nearly spherical, pebbly, usually with a pair of ridges down the otherwise rounded back, distinctly beaked.
- Notes: The fruits are eaten by waterfowl.
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