What is an asparagus fern?

They aren't ferns at all!

Asparagus "ferns" are actually slightly woody evergreen plants that belong to the order Asparagales (genus Asparagus and Protoasparagus), and are often sold as ornamental plants, but are also considered an invasive weed in many parts of the United States and Australia.

They are native to South Africa and are called "asparagus ferns" because, from a distance, they do sort of look like ferns.

"Asparagus ferns" are mostly drought tolerant plants that have an extensive network of storage roots. The produce small white flower during the summer months, the fruits measure between 3 and 4mm in diameter and turn black on maturity.