Tall Waterhemp

Waterhemp (Tall or Common)

Amaranthus tuberculatus (Moq.) Sauer

(includes plants once classified as Amaranthus rudis J.D. Sauer)

Amaranthaceae (Pigweed Family)

▲ seedlings

▲ ▼ young plants

▲ ▼ young, mature plants

▲ ▼ plants showing different stem colors possible, from green to red

▲ ▼ mature plants, showing elongated inflorescences

▲ ▼ inflorescences

Amaranthus tuberculatus (Moq.) Sauer.; Common Waterhemp: (Bayer Code: AMATU; US Code AMTU)

Warm-season, aggressive annual weeds, with upright, pyramidal to slender growth habit
Terminal inflorescences very long--often several feet tall
Has both male and female plants & inflorescences
- Female plant inflorescences appear more “sparse" than male inflorescences
Common in cultivated fields--often most common of pigweeds--and in disturbed soils, roadsides, wetland and non-crop areas
Prefers more moist soil, but can be found in any soil type
Tall waterhemp (Amaranthus tuberculata) and common waterhemp (Amaranthus rudis) were considered as two separate species based on minor seed characteristics differences, but now are considered all one species
Can readily hybridize with other pigweeds, resulting in weeds with varying pigweed/amaranth/waterhemp characteristics
Similar to palmer amaranth in long inflorescences, but waterhemp has narrow, lanceolate leaves, compared to diamond-shaped leaves of palmer amaranth
Can develop colonies of herbicide-resistant plants fairly easily where repeated use of one or similar herbicides is practiced--one of the new "superweeds"

(Updated January 15, 2019)