It is a fern, but I do not know which.

Sensitive Fern.
Called that, I believe, because it caves in completely at the first touch of frost.

After checking some more on Google images, I believe it's a Wort Fern. The tell-tale bumps on the back of the leaf are not evident in this photo, but they are there.

Thanks for the guesses.

Vince

Don't think so. You don't say where you are but Wart Fern is a tropical plant and doesn't look much like your sample imo. All ferns get bumps, ie spore bearing bodies, on the backs of the leaves. But Wart Fern has bumps visible on the tops. I don't see any on yours. Plus the fronds are slimmer, pointier and more clearly opposite than on your specimen.