Kruckeberg's Hollyfern

Polystichum kruckebergii is widely but sporadically distributed in small numbers in both the Sierra-Cascade and Rocky Mountain systems. Populations sometimes consist of only two or three dwarfed plants that are difficult to distinguish from P . scopulinum , with which they may occur. The spreading teeth of equal size at the pinna apex will usually distinguish this species. Polystichum kruckebergii is a tetraploid presumed to be of hybrid origin, with P . lonchitis and P . lemmonii as its diploid progenitors (W. H. Wagner Jr. 1973), although this hypothesis has not been confirmed. The hybrid with P . munitum has been found in Washington (P. S. Soltis et al. 1987) with both parents, and it is distinguished by intermediate morphology and abortive sporangia.

Stems ascending. Leaves erect, 1--2.5 dm; bulblets absent. Petiole 1/10--1/5 length of leaf, sparsely scaly; scales light brown, gradually diminishing in size distally. Blade linear, 1-pinnate-pinnatifid, base narrowed. Pinnae rhombic-ovate to short-falcate, proximal pinnae ± triangular; pinnae overlapping, twisted somewhat out of plane of blade, 0.5--1.5 cm; base oblique, acroscopic auricle well developed; margins shallowly incised to merely dentate or serrulate, teeth spreading and spiny at tip; apex acute with subapical and apical teeth same size; microscales lanceolate with few projections, confined to costa, on abaxial surface only. Indusia entire. Spores dark brown. 2 n = 164.

B.C.; Calif., Idaho, Mont., Nev., Oreg., Utah, Wash.

Rocks and cliffs in subalpine to alpine habitats; 1500--3200m.

Polystichum kruckebergii is a species of fern known by the common names Kruckeberg's sword fern and Kruckeberg's hollyfern. It is native to western North America from Alaska to Utah to California, where it grows in rocky mountain habitat in subalpine and alpine climates.

This fern produces several narrow, erect leaves 10 to 25 centimeters long. Each leaf is made up of many oval to triangular leaflets, each no more than about 1.5 centimeters long. The leaflets overlap and are somewhat twisted in their axes. Their edges are cut or toothed, the teeth sometimes tipped with spines.