Amaranthus tuberculatus, commonly known as roughfruit amaranth, rough-fruited water-hemp, tall waterhemp, or common waterhemp, is a species of flowering plant. It is a summer annual broadleaf with a germination period that lasts several months. Tall waterhemp has been reported as a weed in 40 of 50 U.S. states. Morphology A distinguishing characteristic of tall waterhemp that sets it apart from similar members of the genus Amaranthus is the lack of hair on its stems and leaves. This characteristic gives the plant a bright, glossy appearance. The leaves of tall waterhemp tend to be long and narrow. The stem is typically erect and slender and can be up to three feet long. The color of the stem is green or red. Tall waterhemp is a dioecious plant. The seedhead branches in the female are numerous, short, and smooth. The male seedhead branches are fewer, longer, and more slender than those of the female. The species has terminal spike inflorescences and very short bracts with simple to highly branched flowers. Seed produced is reddish to black and less than 1/32 inch in diameter. Geographic distribution Tall waterhemp is native to North America. It is believed to have originally had a range north of Missouri and Tennessee to the Great Lakes. It is now found in 40 states but is most common in the Great Plains and Great Lakes regions. Habitat Tall waterhemp predominantly grows in wet habitats, such as ponds, marshes, lakes, creeks, and other riparian zones. It also thrives along roadways and railroads as well as agricultural fields. It can grow in a variety of climates, as evidenced by its widespread range. Growth and development Tall waterhemp is a summer annual that produces a large number of very small seeds. It is considered an r-strategist. Emergence can span several months and often occurs later in the season than other annual weeds, allowing the weed to evade typical weed control strategies such as herbicide application and tillage. One study observed 80% emergence not occurring until ten weeks after the initial emergence. Extreme temperatures have little effect on seed viability. Germination occurs typically after soil temperature alternation, as this is required to break seed dormancy. Waterhemp has been found to germinate in a wide range of soil and temperature conditions. It has been found to germinate 17 years after seed set. While tall waterhemp cannot self-pollinate, due to having separate male and female