Between July and September, it puts on a rogue show of thistle-shaped purple flowers that bob over black-mottled bracts — hence the name. It's considered invasive and noxious across most U.S ...

It is called a thistle cup because its shape is designed to look like the head of a thistle flower. The base is rounded and the rim turns outwards at the edge, which copies the shape of the flower.

The midrib underneath the sow thistle leaf usually has no hairs, whereas the midrib of hawksbeard leaves often does have hairs. The shape of the flower head tends to differ as well, and the leaves of ...

disk-shaped, and covered in spines often found with multiple flowers per stem wind dispersed seeds carried by clusters of cotton-like fuzz Note: European marsh thistle is distinguished from Canada ...