HERE is my thread from last year on aralia, you might check it out.

Looks like the non-native Aralia elata, not the native Aralia spinosa.

Without a location from the OP, it would be difficult to determine native or not but my first thoughts were A. elata also.

Most obvious difference between the two is the architecture of the inflorescences.

...or the presence/absence of leaf petioles

Thanks everyone! I'm located in East Tennessee. I'm assuming it's not a desirable plant to have in a landscape.

"I'm assuming it's not a desirable plant to have in a landscape."

That depends entirely in whether or not you like them. Some find them to be an attractive landscape addition, if not a very friendly one :-)

They sprout all over the place and are hard to remove. I'd get rid of it and it won't be easy.