Polystichum scopulinum |
Polystichum acrostichoides |
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Eaton's holly fern, mountain holly fern, polystic des rochers, rock sword fern |
Christmas fern, polystic faux-acrostic |
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Stems | ascending. |
erect. |
Leaves | erect, 1–3(–5) dm; bulblets absent. |
dimorphic (only in this species); fertile pinnae distal, much contracted; sterile leaves arching, 3–8 dm; bulblets absent. |
Petiole | 1/5–1/3 length of leaf, densely scaly but scales falling off distally; scales light brown, abruptly diminishing in size distally. |
1/4–1/3 length of leaf, densely scaly; scales light brown, diminishing in size distally. |
Blade | narrowly lanceolate, 1-pinnate-pinnatifid, base narrowed. |
linear-lanceolate, 1-pinnate; base narrowed. |
Pinnae | oblong-lanceolate, overlapping, folded inward and twisted horizontally, 1–3 cm; base oblique; margins serrulate with teeth curved inward; apex obtuse to cuspidate with subapical teeth smaller than apical tooth; microscales narrowly lanceolate, with stout projections, sparse, on abaxial surface only. |
oblong to falcate, not overlapping, in 1 plane, 2–6 cm; base oblique, acroscopic auricles well developed; margins serrulate-spiny with teeth ascending; apex acute or blunt with subapical and apical teeth same size; microscales filiform, lacking projections, dense, on abaxial surface only. |
Indusia | entire-ciliate. |
|
Sori | confluent, completely covering abaxial surface of pinnae (only in this species); indusia entire. |
|
Spores | brown. |
light brown. |
2n | = 164. |
= 82. |
Polystichum scopulinum |
Polystichum acrostichoides |
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Habitat | Rock crevices and at base of boulders, serpentine to acidic substrates, usually exposed to full sun | Forest floor and shady, rocky slopes |
Elevation | 0–3500 m (0–11500 ft) | 0–1500 m (0–4900 ft) |
Distribution |
AZ; CA; CO; ID; MT; NV; OR; UT; WA; WY; BC; NF; QC
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AL; AR; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; VT; WI; WV; NB; NS; ON; PE; QC; Mexico; naturalized in Europe
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Discussion | Polystichum scopulinum is widely distributed in the United States west of the 110th meridian, where it occurs in sporadic, usually small populations. The species is abundant only on montane serpentine outcrops. The populations in Newfoundland and Quebec are dramatically disjunct. Polystichum scopulinum is an allopolyploid, believed on morphologic grounds to be derived from P. imbricans × lemmonii (D. H. Wagner 1979). Based on putative hybridization between P. scopulinum and P. munitum (P. S. Soltis et al. 1989; W. H. Wagner Jr. 1973), however, P. munitum may also be involved. This hybrid is discussed under P. californicum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Polystichum acrostichoides is a common species most closely related to P. munitum (G. Yatskievych et al. 1988), which also occurs extensively on forest floors. The dimorphic pinnae of Polystichum acrostichoides are not unique to the genus; they are found also in some Asian species. Numerous variants have been named, mostly as forms, but none are of taxonomic consequence. Hybrids are known with P. braunii (P. × potteri Barrington) and P. lonchitis (P. × hagenahii Cody). The latter hybrid is rare, known only from its type locality in Ontario, where it grows with both parents. It is recognized by its intermediate morphology (leaves wider than P. lonchitis, narrower than P. acrostichoides, with slightly contracted sorus-bearing pinnae) and malformed sporangia and spores. Polystichum × potteri is much more widespread, from Nova Scotia, New Brunswick, and Quebec through New England to Pennsylvania. It resembles P. braunii but has narrower leaves bearing malformed sporangia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 2. | FNA vol. 2. |
Parent taxa | Dryopteridaceae > Polystichum | Dryopteridaceae > Polystichum |
Sibling taxa | ||
Synonyms | Aspidium aculeatum var. scopulinum, P. mohrioides var. scopulinum | Nephrodium acrostichoides |
Name authority | (D. C. Eaton) Maxon: Fern Bull. 8: 29. (1900) | (Michaux) Schott: Gen. Fil. plate 9. (1834) |
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