IDENTIFICATION
Biennial.
At 4 - 5 centimetres, bull thistle's large, bright pink (to dark
purple) flowers are hard to miss. Blooms form at the ends of branches,
supported by equally large, spine-covered bracts.
Deeply divided leaves have stout spines at the ends and at the tips of
each segment. Leaves clasp the stem with distinctive spiny wings. Mature
height ranges from 0.3 to 2 metres tall. First year growth is a rosette.
DAMAGE
Heavy infestations can exclude livestock from areas and the presence of
bull thistle in hay decreases forage value.
HABITAT
Bull thistle grows in dry to moist habitats that include roadsides,
cultivated fields, pastures, logged forestland, and disturbed
sites. It is generally intolerant to shade. It is widespread and abundant
in all areas of British Columbia.
SPREAD
Seeds are highly viable and usually
germinate rapidly whenever conditions are favourable. Seeds have silky
down and can be windblown for long distances, but most seeds land near
the parent plant.
