Introduction

Notholaena greggii is a species of northern Mexico. It extends barely into the US in the Big Bend area of Texas, where all known populations occur within 25 km of the Mexican border (Windham, 1993a). Morphology strongly suggests that it is most closely related to N. bryopoda; plastid DNA sequence data are equivocal, and place N. greggii in an unresolved position within core Notholaena II (Rothfels et al., 2008). Notholaena greggii prefers limestone ledges or gypsum-rich habitats, but is not as specialized a gypsum species as N. bryopoda.