Another week, another “I Spy in the Sea to Sky”! How many of you got last week’s riddle? Hopefully this new one stands out to you, with its spiny stature and purple blooms!
Bull Thistle (Cirsium vulgare) was brought over to North America from Eurasia as a seed contaminant and can be found in abundance in the Sea to Sky region.
Although visually similar to native thistles, this nasty weed is much pricklier. Its purple flowers are 2.5 cm to 4 cm wide, accompanied by dull leaves with pointy white hairs on the underside. Along the stems are spiny “wings” that look like a continuation of the leaves, giving them a villainous look. Believe it or not, these spiky plants can grow up to 2 meters tall!
Bull Thistle is an aggressive weed that can out-compete native plants and form monocultures. Commonly found in disturbed soils, it decreases forage value (when harvested with hay), overruns clear-cuts, and restricts access to recreational sites. Hardy as it may be, this resilient weed tolerates very little shade, growing among the sunniest patches of an infested area.
This petulant plant is placed under the “strategic control” category under SSISC’s priority species list. That means, due to its widespread distribution, control measures are implemented only in high priority areas in the Sea to Sky, like wildlife corridors.
Think you’ve spotted Bull Thistle? Report it here or email us at email@example.com. If you choose to do some weed control yourself, hand-pulling small infestations (please wear gloves!) or mowing close to the surface several times a year, have proven to be effective methods. Plants that are cut prior to flowering can be left aside to decompose. If they are cut post-flowering, bag, seal, and dispose of the waste in the household garbage stream at the landfill or transfer station. Do not compost!