Polystichum braunii |
Dryopteridaceae |
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Braun's holly-fern, polystic de Braun |
wood fern family |
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Habit | Plants perennial, terrestrial or on rock, occasionally hemiepiphytic or epiphytic. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Stems | erect. |
creeping to erect, rarely arborescent, sometimes climbing, branched or unbranched, dictyostelic, bearing scales. |
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Leaves | monomorphic, arching, 2–10 dm; bulblets absent. |
circinate in bud, monomorphic or dimorphic. |
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Petiole | 1/8–1/6 length of leaf, densely scaly; scales light brown, gradually diminishing in size distally. |
usually not articulate to stem, scales usually persistent at base, in cross section with 2–many roundish bundles, or bundles 2 and lunate. |
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Blade | broadly lanceolate, 2-pinnate; base narrowed. |
simple to commonly 1–5-pinnate or more divided, leaf buds absent or present. |
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Pinnae | oblong-lanceolate or falcate, proximal pinnae ± rectangular, not overlapping, in 1 plane, 2–10 cm; base oblique except proximal 3–4 pinnae, where auricles not developed; apex acute, subapical and apical teeth same size; microscales filiform to linear, lacking projections, dense abaxially, sparse adaxially. |
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Veins | pinnate or parallel in ultimate segments, simple or forked, free or anastomosing, areoles sometimes with included free veinlets. |
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Indusia | ciliate. |
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Sori | borne abaxially on veins or at vein tips (but usually not marginal), or sporangia acrostichoid and covering abaxial surface, if in discrete sori then variously shaped (round, oblong, or elongate); receptacle not or only slightly elevated, with or without indusium, indusium variously linear, falcate, or reniform, sometimes hoodlike, cuplike, or round. |
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Sporangia | with stalk of 2–3 rows of cells; annulus vertical, interrupted by stalk. |
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Spores | brown. |
all of 1 kind, usually not green (except Matteuccia, Onoclea), oblong or reniform in outline, monolete, variously ornamented (often broadly winged), 64 per sporangium (32 in apogamous spp.). |
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Gametophytes | green, aboveground, cordate, glabrous or often bearing glands or hairs; archegonia and antheridia borne on lower surface, antheridia 3-celled. |
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Pinnules | ± stalked, short-falcate to oblique-rhombic, acroscopic auricle well developed on proximal pinnules; margins dentate, with slender bristle tips; apex broadly acute. |
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Indument | on blade commonly of glands, hairs, and/or scales, especially on rachis and costae abaxially. |
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2n | = 164. |
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Polystichum braunii |
Dryopteridaceae |
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Habitat | Moist places in boreal forests, interior moist forests | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Elevation | 0–300 m (0–1000 ft) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Distribution |
AK; CT; ID; MA; ME; MI; MN; NH; NY; VT; WI; BC; NB; NF; NS; ON; QC; YT; SPM; Eurasia
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Worldwide |
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Discussion | Because no diploid ancestors have been found, Polystichum braunii is thought to be an ancient tetraploid. Its sterile hybrid with P. acrostichoides, P. × potteri, is discussed under P. acrostichoides. Polystichum braunii × lonchitis has been reported from southeast Alaska (S. L. Welsh 1974). This hybrid has been cytologically confirmed in Europe and named P. × meyeri Sleep & Reichstein (A. Sleep and T. Reichstein 1967). It has narrower and less divided leaves than P. braunii and poorly developed auricles. Polystichum braunii × lonchitis was described by J. Ewan (1944), but the type (from British Columbia) is P. braunii × munitum (A. Sleep and T. Reichstein 1967). This latter hybrid is the postulated progenitor of P. setigerum (D. H. Wagner 1979). North American P. braunii has been segregated as var. purshii Fernald, distinguished from European populations (var. braunii) by having broader microscales. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
The family Dryopteridaceae has been variously circumscribed; it is here delimited in a manner similar to that of R. M. Tryon and A. F. Tryon (1982) but with the inclusion of Nephrolepis. In many works, the family has gone under the illegitimate name Aspidiaceae. Some authorities define Dryopteridaceae more narrowly, to exclude Athyrium, Deparia, Diplazium, Cystopteris, and Gymnocarpium (Athyriaceae or Woodsiaceae), Woodsia (Woodsiaceae), Lomariopsis (Lomariopsidaceae), Nephrolepis (Nephrolepidaceae or Davalliaceae), Onoclea and Matteuccia (Onocleaceae), and Ctenitis and Tectaria (Tectariaceae). Characteristics holding Dryopteridaceae (as circumscribed here) together include the bilateral, monolete spores, often broadly winged perispore, absence of needlelike hairs, scaly stem and petiole bases, abaxial (nonmarginal) sori, base chromosome number of 40 or 41 (also 38 and 39 in Woodsia, 37 in Onoclea, 42 in Cystopteris), and usually indusiate sori. Loss of indusium, dimorphism, areolate venation, and reduced blade dissection have occurred repeatedly along many evolutionary lines in Dryopteridaceae, and in general these characteristics are often not very useful in delimiting genera or assessing intergeneric relationships. In some genera, especially Phanerophlebia and Polystichum, the blade bears very narrow scales (sometimes called microscales) that resemble uniseriate hairs. These scales may be only one or two cells wide. Every intergradation exists between these filiform microscales and more typical, wider scales, and the two types are the same color, generally tan to brownish. Microscales are probably not homologous with true hairs, which may be either unicellular or multicellular, uncolored or sometimes reddish (as in Tectaria and Ctenitis), glandular (as in Woodsia) or not. Hairs in Dryopteridaceae, if present at all, are generally readily distinguishable from the needlelike, transparent ones found in Thelypteridaceae. Genera ca. 60, species perhaps exceeding 3000 (18 genera, 79 species in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 2. | FNA vol. 2, p. 246. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Parent taxa | Dryopteridaceae > Polystichum | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Sibling taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Synonyms | Aspidium braunii, P. braunii subsp. purshii, P. braunii var. purshii | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | (Spenner) Fée | Herter | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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