Birdfoot Cliffbrake

Pellaea mucronata encompasses two morphologic extremes that tend to occupy different habitats and are treated here as subspecies. The typical 3-pinnate form ( P . mucronata subsp. mucronata ) is scattered throughout California and southern Nevada, usually below 1800 m elevation. The 2-pinnate form with ascending, overlapping pinnae ( P . mucronata subsp. californica ) is apparently confined to the Sierra Nevada and Transverse Ranges of California at elevations greater than 1800 m. The taxonomic status of these entities remains in dispute, and they are often treated as mere ecological forms. W. H. Wagner Jr. et al. (1983) indicated that natural hybrids formed between P . bridgesii and these two taxa are morphologically distinct, suggesting that the differences observed between the subspecies of P . mucronata are genetically based. In addition to P . bridgesii , subsp. mucronata apparently hybridizes with both P . truncata and P . brachyptera (see comments under those species).

Stems compact, ascending, stout, 5--10 mm diam.; scales bicolored, linear-subulate, 0.1--0.3 mm wide, centers black, thick, margins brown, thin, erose-dentate. Leaves monomorphic, clustered on stem, 7--45 cm; croziers sparsely villous. Petiole dark brown, lustrous, flattened to slightly grooved adaxially, without prominent articulation lines. Blade ovate-deltate, (2--)3-pinnate proximally, 4--18 cm wide; rachis brown throughout, straight, shallowly grooved adaxially, usually glabrous. Pinnae perpendicular to rachis to strongly ascending, not decurrent on rachis, usually with 9--40 ultimate segments; costae straight, 10--70 mm, much longer than ultimate segments. Ultimate segments narrowly oblong, 2--12 mm, leathery, glabrous; margins recurved to strongly revolute on fertile segments, usually covering more than 1/2 abaxial surface, borders greenish, usually dentate; apex mucronate. Veins of ultimate segments obscure. Sporangia short-stalked, containing 64 spores, intermixed with abundant farina-producing glands.

Allosorus mucronatus D. C. Eaton, Amer. J. Sci. Arts 22: 138. 1856; Pellaea ornithopus Hooker

Pellaea mucronata is a species of fern known by the common name bird's foot cliffbrake.

It is native to much of California, and parts of Oregon, Nevada, Arizona, and Baja California, where it grows in various types of rocky habitat. The subspecies californica is limited to California, while ssp. mucronata can be found outside that state's borders.

Each leaf is 7 to 45 centimeters long and is borne on a thin petiole. It is composed of a thin, straight, brown rachis lined with widely spaced leaflets. The leaflets are divided into small narrow terminal segments, or these may be subdivided into another set of segments. The smallest segment measures up to about a centimeter long and is green to dark purplish in color. The edges may be rolled under. The sporangia are located under the edges.