Waterhemp
Amaranthus tuberculatus
Washington State Classification
Class A — Eradication Required Statewide
Waterhemp grows fast, has high seed production, and is drought tolerant.
Quick Reference
Identification
Growth Habit
Waterhemp is a summer annual, broadleaf herbaceous plant, which grows p to 3 meters in height, but can be much shorter.
Leaves
Leaves are attached to the main stem by stalks, which grow alternately up the stem. Leaves can be egg, lance, or diamond shaped. They can grow to 4 inches long and over 1 inch wide.
Flowers
Flowers are light green, inconspicuous, not showy, and grow in clusters on spikes at the tops of the plants or along the stems near where the leaves grow. Male and female flowers grow on separate plants. Male plants have softer flowering clusters, which have a lot of pollen when mature. Female plants' flower clusters are much more bristly to the touch.
Fruit & Seeds
Seeds are very tiny (about 1mm long), dark brown to black, and are very numerous.
Impact
Waterhemp grows fast, has high seed production, and is drought tolerant. It is highly competitive in crop fields. Due to herbicide resistances, waterhemp is difficult to control once established.
Ecology & Spread
Habitat
Despite growing well in wet and riparian areas, waterhemp is very drought tolerant and can also grow in dry and disturbed areas. It grows well in agricultural fields.
Spread Mechanisms
Reproduction
Seed only.
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