Which of the following is a Perennial plant?

A perennial plant is characterized by its ability to live for more than two years, developing a root system that allows it to regrow each growing season. Canada Thistle is classified as a perennial because it has a deep and extensive root system that enables it to survive adverse conditions and come back year after year.

In contrast, the other plants listed—Redroot Pigweed, Blue Mustard, and Tumble Mustard—are annuals or biennials, which means they complete their life cycle in one growing season or over two years, respectively. While they can establish and produce seeds relatively quickly, they do not have the established long-term living infrastructure like perennial plants, which is a hallmark of Canada Thistle.