Like many other biennial invasives, bull thistle is able to produce a large seed bank that can remain viable for up to 10 years! As a result, the plant can easily spread and form dense stands in ...

Californian thistle is one of the most common thistle species in New Zealand. It is very troublesome in pastures because it is so difficult to control. Once a plant is established in pasture, it forms ...

The Sacramento Mountains thistle is a rare purple flower than can grow to be six feet tall and lives only in wet, high-elevation habitats in the Sacramento Mountains near the town of Cloudcroft, New ...

European marsh thistle, a terrestrial and wetland herbaceous biennial in the Asteraceae family, is an invasive plant that prefers moist soils. European marsh thistle frequently invades fens, wetlands, ...