Date of this Version
The growth and control of Canada thistle is covered here.
Canada thistle plant
Canada thistle [Cirsium arvense (L) Scop.] is a native of Eurasia and was probably introduced to America around 1750. Since that time it has spread throughout the northern part of the United States. Canada thistle is estimated to infest 800,000 acres in northern and western Nebraska.
A perennial that reproduces from seed and by an extensive root system, Canada thistle is dioecious, with the male and female flowers on separate plants. For viable seed to be produced, both male and female plants need to be present.