Which type of thistle possesses a greater root system, Canada thistle or musk thistle?

Canada thistle is known for its extensive and aggressive root system, which can spread over a wide area. This deep and fibrous root network allows Canada thistle to outcompete other plants for water and nutrients, making it a particularly challenging weed in various ecosystems, including those found in right-of-way settings. The roots can regenerate new shoots even after considerable stress, such as herbicide application or mechanical removal, facilitating its persistence.

In contrast, musk thistle has a less extensive root system that does not replicate the same level of aggressiveness as that of Canada thistle. While musk thistle can still pose management challenges, its root system generally does not have the same depth or spread as Canada thistle's, making Canada thistle the more formidable of the two in terms of its ability to colonize and dominate a space.

Thus, option B accurately reflects the significant difference in root systems between the two types of thistle, emphasizing Canada thistle's more extensive root growth.