Flora of North America species comparison

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Polystichum imbricans

Polystichum californicum

imbricate sword-fern, narrow-leaf sword fern, rock sword-fern

California sword-fern
Stems

ascending to erect.

erect or ascending.
Leaves

erect to arching back at tip, 2–8 dm;

bulblets absent.

monomorphic, arching or erect, 2–8 dm;

bulblets absent.
Petiole

1/4–1/3 length of leaf;

scales abruptly diminishing in size distally and falling off early but retaining conspicuous tuft of brown scales at base.

1/5–1/3 length of leaf;

scales light brown, abruptly diminishing in size distally, falling off early distally.
Blade

linear-lanceolate to linear, 1-pinnate, base not or slightly narrowed.

lanceolate to linear-lanceolate, 1-pinnate-pinnatifid, base slightly narrowed.
Pinnae

oblong, slenderly lanceolate, or falcate, usually overlapping, in 1 plane or twisted out of plane of blade, 2–4 cm;

base oblique, auricles well developed;

margins serrulate-spiny with teeth ascending;

apex cuspidate or apiculate with subapical teeth smaller than apical tooth;

microscales lanceolate to linear with straight or sharply angular projections, sparse, on abaxial surface only.

oblong to lanceolate to falcate, shallowly to deeply divided, pinnae overlapping or not, in 1 plane, 2–10 cm;

base oblique, acroscopic auricle lobed;

margins not incised to costae, serrulate-spiny with teeth ascending;

apex acute-attenuate, subapical and apical teeth same size (southern form) or obtuse and cuspidate with subapical teeth smaller than apical teeth (northern form);

microscales filiform, dense abaxially, sparse adaxially.
Indusia

entire to sharply dentate.

ciliate.
Spores

dark brown.

brown.
2n

= 164.

Polystichum imbricans

Polystichum californicum
Habitat On forest floor in southern part of range and in rock crevices at cliff bottoms (most commonly andesite) to north
Elevation 100–850 m (300–2800 ft)
Distribution
from FNA
CA; OR; WA; BC; only in the flora
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
Discussion

Polystichum imbricans is one of the postulated ancestors of two allopolyploids, P. californicum and P. scopulinum (D. H. Wagner 1979). Relationships to P. munitum are discussed under that species.

Subspecies 2.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Polystichum californicum is restricted to the Coast Ranges and the Sierra-Cascade axis. It is most abundant in the Coast Range north of San Francisco.

Polystichum californicum is an allopolyploid, the evolutionary roots of which include P. dudleyi as the 2-pinnate ancestor. Morphologic and ecological data indicate P. imbricans is ancestor to the northern forms and P. munitum is ancestor to southern forms, suggesting P. californicum is an amalgam of interfertile tetraploids with polyphyletic origins (D. H. Wagner 1979). Cytological analysis corroborates this (A. D. Callan 1972; W. H. Wagner Jr. 1973), but chloroplast DNA studies have detected only the involvement of P. imbricans in the ancestry of P. californicum (P. S. Soltis et al. 1991).

The more xeric, rock-inhabiting members of the complex (showing the parental influence of P. imbricans) occupy the northern half of the range whereas plants of more mesic habitats are found to the south. Hybrids with both P. dudleyi and P. munitum are found frequently, because these three species are often sympatric (W. H. Wagner 1973). The hybrid with P. dudleyi (a triploid) will key to that species. The hybrid with P. munitum resembles a less-incised form of P. californicum with aborted sporangia. Polystichum californicum × imbricans has been found only once, in Oregon (A. D. Callan 1972). Another hybrid that will key here, based on its overall appearance, is P. munitum × scopulinum. It lacks filiform microscales and also has malformed sporangia. Such a specimen was the basis of the report of Polystichum californicum in eastern Washington (C. L. Hitchcock et al. 1955–1969, vol. 1). The sterile diploid hybrid between P. dudleyi and P. munitum is indistinguishable from P. californicum except for aborted sporangia and chromosome number (W. H. Wagner Jr. 1973).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Pinnae oblong, less than 5 times longer than wide, adaxial surfaces facing upward and twisted out of plane of blade; leaves stiffly erect to tip; at base of boulders or in cliff crevices in exposed sites; California to British Columbia.
subsp. imbricans
1. Pinnae narrowly lanceolate, more than 5 times longer than wide, generally in 1 plane; leaf tips arching back; on forest floor in shade; only in California.
subsp. curtum
Source FNA vol. 2. FNA vol. 2.
Parent taxa Dryopteridaceae > Polystichum Dryopteridaceae > Polystichum
Sibling taxa
P. acrostichoides, P. aleuticum, P. andersonii, P. braunii, P. californicum, P. dudleyi, P. kruckebergii, P. kwakiutlii, P. lemmonii, P. lonchitis, P. microchlamys, P. munitum, P. scopulinum, P. setigerum
P. acrostichoides, P. aleuticum, P. andersonii, P. braunii, P. dudleyi, P. imbricans, P. kruckebergii, P. kwakiutlii, P. lemmonii, P. lonchitis, P. microchlamys, P. munitum, P. scopulinum, P. setigerum
Subordinate taxa
P. imbricans subsp. curtum, P. imbricans subsp. imbricans
Synonyms Aspidium munitum var. imbricans, P. munitum subsp. imbricans, P. munitum var. imbricans Aspidium californicum, P. aculeatum var. californicum
Name authority (D. C. Eaton) D. H. Wagner: Pteridologia 1: 50. (1979) (D. C. Eaton) Diels: in Engler & Prantl, Nat. Pflanzenfam. 1(4): 191. (1899)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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