There is a legend that Canada thistle docs not reproduce viable seed in southern Iowa. There exists diversity of recorded statement as to whether the root or the stem is responsible for the vegetative spreading of this plant. The deep-penetrating and horizontally growing root of Canada thistle appears, if judged by structure and behavior, to be organized for extension of its area of occupation, for water and nutrient absorption, as well as for food storage. It bears numerous upward-growing, stem-producing buds whose photosynthetic activity maintain its supply of carbohydrate food. The plant seeds throughout Iowa wherever male and female plants grow sufficiently close to each other.
Proceedings of the Iowa Academy of Science
©1932 Iowa Academy of Science, Inc.
"Iowa Field Notes on Reproduction of Canada Thistle (Cirsium arvense),"
Proceedings of the Iowa Academy of Science, 39(1), 137-137.
Available at: https://scholarworks.uni.edu/pias/vol39/iss1/25