Notholaena aschenborniana
Linnaea 20: 417. 1847.
Stem scales concolored, margins black, undifferentiated, thick, ciliate. Leaves 8–35 cm. Petiole black, much shorter than blade, rounded adaxially, covered with ciliate and stellate scales. Blade lanceolate, usually 2-pinnate, 3–6 times longer than wide, abaxially with whitish or yellowish farina completely concealed by overlapping ciliate and deeply dissected stellate scales, adaxially with scattered stellate scales; basal pinnae equal to or slightly smaller than adjacent pair, ± equilateral, proximal basiscopic pinnules not greatly enlarged. Ultimate segments sessile to subsessile, narrowly adnate to costae; segment margins slightly recurved, rarely concealing sporangia. Sporangia containing 32 spores. n = 2n = 90, apogamous.
Phenology: Sporulating summer–fall.
Habitat: Rocky slopes and cliffs, apparently confined to limestone
Elevation: 300–1900 m
Distribution
Ariz., Tex., Mexico
Discussion
Although Notholaena aschenborniana is often described as nonfarinose, the abaxial glandular farina characteristic of all species of Notholaena as defined here is present beneath the dense covering of scales. All individuals examined chromosomally by M. D. Windham (unpublished data) were apogamous triploids that apparently arose through autopolyploidy. Further investigation is necessary to determine whether or not 64-spored, diploid populations of N. aschenborniana are still extant.
Selected References
None.