colony-forming weed, growing up to 6 feet tall, with a spiny stem
and long fleshy taproot. Musk thistle reproduces solely by seed.
inflorescence is terminal, solitary, 1 ½ to 3 inches in diameter,
and usually bent over. They are deep rose, violet, purple, or occasionally
white in color. There are broad, spine-tipped bracts found directly
below the inflorescence.
yellowish-brown with a plume of white hair-like fibers, 3/16 inch
green with a light green midrib, deeply lobed, with spiny margins.
thistle invades pasture, range, and forestlands. It is often found
on roadsides, waste areas, ditch banks, stream banks and in grain
fields. It spreads rapidly, forming extremely dense stands that
crowd out desirable forages. Musk thistle is shade intolerant.
to a broad range of soils, establishment is best on bare soil. Musk
thistle is tolerant of saline and acidic soils.
thistle is a noxious weed in Utah. Chemical control is effective.
An introduced biological control agent, the musk thistle weevil,
feeds on the seeds and can limit the spread of this plant. but will
not eliminate it.
Musk thistle is not palatable to livestock because of its long sharp
spines. Musk thistle does provide a source of nectar for high quality