Pellaea atropurpurea |
Pteridaceae |
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pelléade à stipe pourpre, purple cliff-brake, purple-stem cliff-brake |
brake family, maidenhair fern family |
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Habit | Plants perennial [annual], on rock or terrestrial, of small (rarely large) stature. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Stems | compact, ascending, stout, 5–10 mm diam.; scales uniformly reddish brown (or tan), linear-subulate, 0.1–0.3 mm wide, thin, margins entire to denticulate. |
compact to creeping, branched or unbranched, dictyostelic, bearing hairs and/or scales. |
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Leaves | somewhat dimorphic, sterile leaves shorter and less divided than fertile leaves, clustered on stems, 5–50 cm; croziers villous. |
monomorphic to dimorphic, circinate or noncircinate in bud. |
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Petiole(s) | reddish purple to nearly black, lustrous, rounded adaxially, without prominent articulation lines. |
usually with persistent scales proximally, lacking spines; vascular bundles 1–several, roundish or crescent-shaped in cross section. |
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Blade(s) | elongate-deltate, usually 2-pinnate proximally, 2–18 cm wide; rachis reddish purple throughout, straight, rounded adaxially, densely pubescent adaxially with short, curly, appressed hairs. |
1–6-pinnate, without laminar buds. |
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Ultimate segments | linear-oblong, 10–75 mm, leathery, sparsely villous abaxially near midrib; margins weakly recurved to plane on fertile segments, usually covering less than 1/2 abaxial surface, borders whitish, crenulate; apex obtuse to slightly mucronate. |
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Pinnae | perpendicular to rachis or ascending, not decurrent on rachis, usually with 3–15 ultimate segments; costae straight, 10–100 mm, often longer than ultimate segments. |
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Veins | of ultimate segments obscure. |
pinnate or parallel in ultimate segments of blades, simple or forked, free or infrequently anastomosing in complex patterns. |
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Indusia | (when present) formed by reflexed, recurved, or revolute leaf margin (false indusium). |
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Sori | borne abaxially on veins, often confluent with age and forming a continuous submarginal band, or sporangia densely covering abaxial surface (acrostichoid); receptacle not or only slightly elevated. |
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Sporangia | long-stalked, containing 32 spores, not intermixed with farina-producing glands. |
stalk of 2–3 rows of cells; annulus vertical, interrupted by stalk; spores 64 or 32 (rarely 16) per sporangium. |
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Spores | all 1 kind, brown, black, or gray (rarely yellow), globose to globose-tetrahedral or trigonal, occasionally with prominent equatorial ridge, trilete, or trigonal, variously ornamented (usually cristate or rugose). |
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Gametophytes | green, aboveground, obcordate to reniform, sometimes asymmetric, usually glabrous (glandular-farinose in Notholaena); archegonia and antheridia borne on abaxial surface, antheridia 3-celled. |
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n | = 2n = 87, apogamous. |
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Indument | on petioles, rachises, costae, and blades, rarely absent or commonly of hairs, glands, and/or scales, occasionally of white or yellow farina. |
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Pellaea atropurpurea |
Pteridaceae |
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Phenology | Sporulating summer–fall. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Habitat | Calcareous cliffs and rocky slopes, usually on limestone | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Elevation | 100–2500 m (300–8200 ft) | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Distribution |
AL; AR; AZ; CO; CT; DC; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; MI; MN; MO; MS; NC; NE; NJ; NM; NV; NY; OH; OK; PA; RI; SC; SD; TN; TX; UT; VA; VT; WI; WV; WY; ON; QC; Mexico; Central America in Guatemala
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Worldwide |
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Discussion | Contrary to D. B. Lellinger's (1985) hypothesis, isozyme data indicate that neither Pellaea glabella nor P. ternifolia was involved in the origin of this apogamous triploid. Instead, it appears that P. atropurpurea is an autopolyploid derivative of a single diploid taxon that has not yet been located. A thorough survey of spore number per sporangium in this species should be undertaken to determine whether the diploid progenitor is still extant. Collections from western Canada identified as P. atropurpurea actually represent P. gastonyi, an apogamous tetraploid produced by hybridization between P. atropurpurea and diploid populations of P. glabella. Pellaea atropurpurea has also hybridized with P. wrightiana; the hybrid is a rare apogamous pentaploid known only from western Oklahoma. Pellaea lyngholmii is the apogamous tetraploid hybrid between P. atropurpurea and P. truncata. Pellaea atropurpurea is distinguished from all these hybrids by having rachises that are densely pubescent adaxially, larger ultimate segments, and spores averaging less than 62 µm in diameter. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Considerable disagreement exists concerning the circumscription and proper name of this family. The taxa comprising the Pteridaceae in this treatment were assigned to the Sinopteridaceae and Pteridaceae by D. B. Lellinger (1985) and were included in five families by R. E. G. Pichi-Sermolli (1977). The broad concept followed here is similar (except for the exclusion of Ceratopteris) to that espoused by R. M. Tryon and A. F. Tryon (1982), who applied the name Pteridaceae to the group. Until very recently, the newer name Adiantaceae was more commonly used. As represented in North America, Pteridaceae comprise three major evolutionary lines (the adiantoids, the pteroids, and the cheilanthoids). Characteristics holding the family together include abaxial (usually submarginal) sori that lack indusia or are protected by a reflexed or revolute leaf margin, spores that are usually globose-tetrahedral and trilete, and chromosome base numbers of 30 or 29 (rarely 27). The xeric-adapted members of the family (particularly the cheilanthoids) have undergone extensive parallel and convergent evolution, and they have frustrated attempts to produce a natural generic classification based on macromorphologic characteristics alone. Although some workers have aggregated species into a few large genera (e.g., J. T. Mickel 1979b), most tend to recognize smaller segregate genera based on a combination of morphologic, chromosomal, and biochemical data. The latter approach seems to provide a more useful, evolutionarily informative classification and is the one adopted here. Aspidotis and Notholaena are maintained here as distinct from Cheilanthes, and three recently described genera (Argyrochosma, Astrolepis, and Pentagramma) have been incorporated into the treatment. The reasons for these changes in generic circumscription are discussed under the individual genera. Genera ca. 40, species ca. 1000 (13 genera, 90 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. 122. | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Parent taxa | Pteridaceae > Pellaea | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Sibling taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
Subordinate taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
Synonyms | Pteris atropurpurea, P. atropurpurea var. cristata | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | (Linnaeus) Link: Fil. Spec. 59. (1841) | E. D. M. Kirchner | ||||||||||||||||||||||||||||||||||||||||||||||||||||
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