Tall Waterhemp

[Amaranthus tuberculatus (Moq.) Sauer]

Amaranthaceae (Pigweed Family)

▲ seedlings

▲ ▼ young plants

▲ ▼ young, mature plants

▲ ▼ mature plants, showing elongated inflorescences

▲ ▼ inflorescences

Waterhemp:  (pp. 34-35, Weeds of the Great Plains—not in Weeds of the Northeast)

o       warm-season, aggressive annual weeds, with upright, pyramidal to slender growth habit

o       terminal inflorescences very long—often several feet tall

o       has both male and female plants & inflorescences

o       female plant inflorescences appear more “sparse” than male inflorescences

o       common in cultivated fields—often most common of  pigweeds—and in disturbed soils, roadsides, wetland and non-crop areas

o       prefers more moist soil, but can be found in any soil type

o       common waterhemp and tall waterhemp are main species found around here—can distinguish only by seed characteristics; some taxonomists now believe they are same species

o       can readily hybridize with other pigweeds, resulting in weeds with varying pigweed/amaranth/waterhemp characteristics

o       can develop colonies of herbicide-resistant plants fairly easily where repeated use of one or similar herbicides is practiced