Milk thistle (Silybum marianum) can be a pain if it's growing ... classified as a noxious weed in several states. It spreads by seed that can remain viable for years, she adds, and 'has the ...

Winged thistle is a winter annual, which means it generally establishes from seed in autumn, grows as a typical thistle ... but not as strongly as in variegated thistle (Silybum marianum). Each flower ...