Notholaena is a genus of ferns in the family Pteridaceae found exclusively in the New World. Ferns of this genus are mostly epipetric (growing on rock) or occurring in coarse, gravelly soils, and are most abundant and diverse in the mountain ranges of warm arid or semiarid regions. They typically have a creeping or erect rhizome and leaves that are pinnatifid to pinnate-pinnatifid with marginal sori protected by a false indusium formed from the reflexed margin of the leaf. Members of Notholaena also have a coating of whitish or yellowish farina (a powdery wax that prevents desiccation) on the surfaces of the leaves. The farina is often limited to the abaxial (lower) leaf surface, but may occur on the adaxial (upper) leaf surface as well.
The similar genus Argyrochosma also has farinose leaves, but in that genus the ultimate segments of the leaves have entire margins and are distinctly stalked, whereas in Notholaena the ultimate segments are usually lobed or pinnatifid and sessile or subsessile. Notholaena has in the past been used as a "catch-all" genus for a wide variety of species that did not fit well in other arid fern genera but it has more recently been defined in a much narrower sense, making the genus much more morphologically and evolutionarily coherent. The genera Argyrochosma and Astrolepis were recently segregated from Notholaena, and other former members of Notholaena are now in the genus Cheilanthes.Selected species
Assessment of the genetic diversity of Frankia microsymbionts of Elaeagnus angustifolia L. plants growing in a Tunisian date-palm oasis by analysis of PCR amplified nifD-K intergenic spacer.(NOTE)
Mar 01, 2007; Abstract: Diversity of Frankia microsymbionts of non-native Elaeagnus angustifolia L. plants spontaneously growing in a Tunisian...