Below North America's moistest, most sheltered, shadowy rock ledges lushly mantled with mosses and ferns, very often the most eye-catching, prettiest fern species are maidenhairs. Maidenhair ferns are easy to identify because their cascading, fanlike fronds seem to be composed of pieces of green confetti held in place by slender, wiry, black or blackish stems. You can see a typical maidenhair colony cascading from a rock face along the Río Escanela in the mountains west of Jalpan below:
I think the above species is ADIANTUM TENERUM, the Fan Maidenhair. Along more exposed, drier limestone roadcuts beside the reservoir road there's a different species, ADIANTUM POIRETII, the Mexican Maidenhair, I think it is. Four maidenhair species are listed for the Reserve area. Nine species are listed in the Flora of North America.
The Fan Maidenhair illustrated in the first picture has a history of medicinal service in Mexico. My Las Plantas Medicinales de Mexico says that country folks use it to stimulate menstrual flow. On the Web various sites also claim that it's good for chest complaints, catarrh, to increase lactation, for bad colds, to aid in kidney function, as an antiparasitic, against dandruff, and, as is clear by now, as "a general cure-all."