Data from: Pellaea zygophylla, a new combination for a distinctive and well-known but neglected fern

Pellaea ovata is a widespread species, sexual diploid in Texas
and northeastern Mexico but an apogamous triploid in northwestern
Mexico, south to northern Argentina, and on Hispaniola. The type
belongs to the southern, apogamous triploid form. Although these two forms
have been discussed repeatedly in the literature, morphological
distinctions between them have been overlooked and they have not been
recognized taxonomically. However, they are distinct. Pellaea ovata s.s.
has puberulent rachides and costae; pinnae usually 2-pinnate with
a well-defined main axis and pinnules borne singly; fertile
pinnules ovate, cordate basally and rounded apically. The sexual
diploid form has rachides and costae glabrous; pinnae
pseudo-dichotomously branched and pinnules usually paired;
fertile pinnules narrowly rounded-trapeziform, obliquely truncate to
cordate basally and truncate apically. Riddell named the sexual
diploid form Pteris zygophylla, from which I give it the new combination
Pellaea zygophylla.