Ordinarily, people don't think of ferns when they think of deserts because most ferns are distributed in wet, humid habitats. Our area has quite a few, although they look shriveled and dead much of the time, that's one of their adaptations to desert conditions. They use water-saving desert adaptations, such as small fronds (leaves) with shading hairs, scales, or waxy coverings to hold in water. When it rains, the dead-looking dry fronds turn green in a few hours and begin the process of photosynthesis.
The plants referred to as "ferns and fern allies" are plants that have vascular tissue (xylem and phloem for conducting water and sugars), but do not produce fruits and seeds. They mostly reproduce by spores or vegetative reproduction. Ferns are very ancient plants that date back more than 300 million years. Their ancestors date back to the Carboniferous period when coal deposits were forming.
Carlsbad Caverns National Park has 13 known species of ferns, including maidenhair fern, cloak fern, lipfern, cliffbrake, and spleenwort. The park's fern allies include one horsetail (also called a scouring rush) and four species of spikemosses, some of which are called "resurrection ferns."
See the park's plant list for all the names.