Which of the following plants is classified as an Annual?

Redroot Pigweed is indeed classified as an annual plant. This classification is based on its life cycle, which typically completes in one growing season. Annuals like Redroot Pigweed germinate, grow, flower, and produce seeds within a year, after which they die. This characteristic allows them to reproduce quickly, often taking advantage of favorable environmental conditions within a single growing season.

On the other hand, the other options refer to plants classified as either perennials or biennials. Field Pennycress is a winter annual, meaning it germinates in the fall and completes its life cycle in the spring. Perennial Sowthistle and Canada Thistle are both perennial species, surviving for multiple growing seasons and reproducing through various means over several years. Perennials typically develop a root system that allows them to grow back even after being cut back or dying back in a particular season.

Thus, the classification of Redroot Pigweed as an annual is significant because it influences its management and control in agricultural practices, especially regarding herbicide application when dealing with different plant life stages.