They spread via seeds and stray plant parts. Since musk thistle (Carduus nutans) can produce over 20,000 straw-colored seeds singularly, it quickly carpets the area, outcompeting native vegetation.

Milk thistle (Silybum marianum) can be a pain if it's growing in your yard. It's non-native and can be an invasive plant, as Keri Wilson, horticulturist and writer for Garden Media Group ...