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SEASONAL IDENTIFICATION
CANADA THISTLE (Cirsium arvense)
SPRING
SUMMER
LATE
SUMMER
SPRING
-
FALL
SUMMER
FALL
-
WINTER
Seedlings and vegetative root sprouts are prevalent in
spring. Look for lobed leaves with spine tips and hairs on
upper leaf surface.
Plants are single stemmed until they develop flower buds.
As flowers emerge, branches develop on the upper portion
of the plant.
Canada thistle colonies in seed are quite noticeable. The
flowers develop into white puffs of cottony seeds that are
dispersed by wind.
Leaves have hairs on the upper surface and are wavy and
lobed with prominent spines at the tip of each lobe. Stems
are hairless.
Round, green flower buds turn purple and produce
attractive purple flower petals. Flowers look like a shaving
cream brush.
Canada thistle retains aboveground form until the first heavy
snow fall. Since this is a perennial weed, the root system
remains alive underground.
