It is called Pteris multifida and it is in the Pteridaceae (Maidenhair Fern Family). Other more familiar genera in the family are Adiantum, Cheilanthes and Pellaea. In Pteris, as other members of the family, the indusia (structures covering the sori) consists of revolute margins. You can see this in the photo of the lower frond surface below.
Sadly, this charismatic fern is not native to North America. It is an Asian species that is sold as a cultivated plant. Like many other cultivated plants, it escapes containers and yards and establishes itself in places native plants could potentially colonize. This specimen was growing on a dripping ledge near one of only two uncapped hot springs. There is a large population of Pteris here growing adjacent to a small population of the native Adiantum capillus-verneris. This is symptomatic of the Hot Springs area in general where total habitat alteration and rapidly colonizing invasive species have left little room or hope for naturally functioning ecosystems.