Even if you have a small outdoor space, it doesn't mean that your plants need to make a small impact. Pick these tall options to make use of vertical space.

A Monarch butterfly feeds on a native tall thistle. Tall thistles, with silvery leaves, flower in August and September and are a good thistle.

Our Mystery Plant (Tall thistle, Cirsium altissimum) is a thistle, and I was able to enter a patch of this stuff on a recent field trip in the upstate of South Carolina. Spiny stuff!

Our Mystery Plant (Tall thistle, Cirsium altissimum) is a thistle, and I was able to enter a patch of this stuff on a recent field trip in the upstate of South Carolina. Spiny stuff!

“Tall thistle and other native thistles are not a problem, and we don’t want people going out and killing the native thistles, but unfortunately, that probably happens a lot,” Moraz said.

Two black swallowtail butterflies, Papilio polyxenes, drink nectar from Field Thistle at Heritage Park in Champaign. Griesbaum Griesbaum Two black swallowtail butterflies, Papilio polyxenes, drink ...

See if you can correctly identify this week's mystery plant. [Answer: "Tall thistle," Cirsium altissimum] Photo by John Nelson ...

“For example, many non-native thistles spread by rhizomes and are very invasive, whereas the tall thistle does not.

Our Mystery Plant is a thistle, and I was able to enter a patch of this stuff on a recent field trip in the upstate of South Carolina. Spiny stuff! It is, in fact, one of a series of species in ...

Our Mystery Plant (Tall thistle, Cirsium altissimum) is a thistle, and I was able to enter a patch of this stuff on a recent field trip in the upstate of South Carolina. Spiny stuff!