Flora of the Canadian Arctic Archipelago


S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, L.J. Gillespie, A.K. Brysting, H. Solstad, and J.G. Harris

Cystopteris fragilis (L.) Bernh.

English: Brittle fern, fragile fern,

French: Cystopté fragile,

Inuktitut: Uivva, uivvaujaq.

Dryopteridaceae, Fern family.

Published in Neues J. Bot. 1(2): 26, plate 2 fig. 9. 1806 [1805].

Type: Plukenet (1696), Almagestum botanicum, tab. 180, fig. 5, selected by Weatherby, Rhodora 37: 376. 1935. Lectotype.

Synonymy. Polypodium fragile L. Sp. Pl. 2: 1091. 1753.

Cystopteris dickieana R.Sim, Gard. Farmers' J. 2, 20: 308. 1848.

Cystopteris fragilis (L.) Bernh. var. dickieana (R.Sim) T.Moore, Handb. Brit. Ferns 81. 1848.

Cystopteris fragilis (L.) Bernh. subsp. dickieana (R.Sim) Hooker f., Student Fl. Brit. Isl. 464. 1870.

Vegetative morphology. Plants (3–)10–25 cm high; perennial herbs; not caespitose; never vegetatively proliferating by bulbils on stems or leaves, in inflorescences, from gemmiphores and gemmae, or by fragmentation. Only fibrous roots present. Roots red-brown, or black (or dark brown). Ground level or underground stems horizontal (covered with erect, old petiole bases); stoloniferous; compact; 2–20 mm wide (often a confused clump-like stem portion). Ground level or underground stems scales present; 1–5 (few). Aerial stems not developed, fern leaves with long petioles arising from a rhizome. Leaves present; arising singly from creeping rhizomes (arising along the horizontal stem); alternate; dying annually and non-persistent, or marcescent (forming a conspicuous grey or brown build-up at the base of the plant). Petioles 15–160(–200) mm long (continental North America petioles (or rachis) with sparse scales at the base, light brown to tan, lanceolate, 0.2–0.4 mm wide; petioles dark at the base but mostly green to straw-coloured, shorter than, or nearly equalling, the blade); glabrescent. Petiole hairs shorter than the diameter of the petiole. Leaf blades compound. Blades 10–150 mm long, 5–35(–50) mm wide (CAN 204410), circinate when young (narrowly elliptic or lanceolate fronds), veins pinnate. Blade adaxial surface without sessile glands, glabrous. Blade abaxial surface glabrous. Blades lobed. Blade margins serrate (margins of the pinnae); apices acute, or obtuse. Leaflet arrangement pinnate (1(-2) pinnate-pinnatifid, widest at the middle or just below).

Reproductive morphology. Sporangia in sori on the undersurface of the leaves. Indusia ovate, whitish, lanceolate scales that fall early.

Chromosome information. 2n = 168, 252, and 336.

2n (4x) = 168. Manton (1950, Europe, 'fragilis' and 'dickieana'); Britton (1953, eastern Canada; 1964, central Canada); Wagner (1955, North America, 'fragilis' and 'dickieana'); Löve and Löve (1961c, Iceland); Sorsa (1961, 1962, Finland); Taylor and Brockman (1966, western Canada); Taylor and Mulligan (1968, western Canada); Löve (1970a, Iceland, 'dickieana'); Löve (1976), 'dickieana' and 'fragilis');

Cody and Mulligan (1982, Canada); Haufler (1986); Dalgaard (1989, western Greenland). Numerous more southern counts.

2n (6x) = 252. Manton and Reichstein (1965, central Europe); Vida (1976, central Europe).

2n (8x) = 336. Vida (1976, central Europe).

Ploidy levels recorded 4x/6x/8x.

Ecology and habitat. Substrates: ridges, cliffs; dry, moderately well-drained areas. Recorded from calcareous ridges with good drainage, rock ledges at the base of cliffs, a calcareous gravel beach (CAN 258542), a limestone gravel beach, dry rocky slopes (CAN 127415), alpine scree, moist rock crevices on a sunny cliff, and a moist habitat with accumulated soil (CAN 518068).

North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago widespread. Uncommon. Arctic, alpine. Arctic islands: Baffin, Devon, Ellesmere, Axel Heiberg, Victoria, Somerset, Southampton, Coats (and Melville Peninsula).

Northern hemisphere distribution. Circumpolar, or circumboreal. Northern Iceland, Northern Fennoscandian, Kanin–Pechora, Svalbard – Franz Joseph Land, Polar Ural – Novaya Zemlya, Yamal–Gydan, Taimyr – Severnaya Zemlya, Anabar–Olenyok, Kharaulakh, Yana–Kolyma, West Chukotka, Wrangel Island, South Chukotka, East Chukotka, West Alaska, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, Ellesmere Land – Peary Land, West Greenland, East Greenland.

General notes. Cystopteris fragilis occurs at higher latitudes and/or elevations than other species of Cystopteris. It is a polymorphic complex, and morphologically distinct hexaploid cytotypes have been reported from disjunct populations in Ontario, Alaska, Arizona, Colorado, Montana, and Wyoming. Isozymic profiles of each of these populations indicate that the hexaploids are polyphyletic and should not be accorded species status (Haufler et al. 1993). Werth and Windham (1991) suggested that this polymorphic polyploid is probably actively speciating at the tetraploid level, perhaps through gene silencing.

The presence of verrucate spores (as opposed to the normal spiny spores) has been used to circumscribe Cystopteris dickieana. It is possible that the verrucate spore is a recessive feature controlled by one gene, or only a few genes. While present at low frequency in much of the range of C. fragilis, verrucate spores are particularly prominent in the Great Plains, and some specimens from the Arctic have been assigned to C. dickieana, although there is no agreement on such assignments.

Elven et al. (2003) discussed the separation of these entities: "The only consistent feature that separates 'dickieana' from 'fragilis' s.s. is the spore ornamentation. In the North Atlantic area there is no connection between this ornamentation and other morphological features, and it is impossible to separate 'dickieana' on macromorphology. It also occurs more or less occasionally within populations [see, e.g., Berg 1992, and Berg, in Jonsell 2000]. Cystopteris dickieana has been finally 'killed' as a taxon by the investigations published by Dyer et al. (2000) [Edinb. J. Bot. 57: 71–81] and Parks et al. (2000) [Edinb. J. Bot. 57: 83–105]. Even if the reticulate spore ornamentation has a certain geographic pattern, this is to be considered as a geographical variation in one character (possibly caused by a single gene), not associated with other characters, and not nearly enough for recognition of a taxon at any level" .

Illustrations. • Habitat: Dorset. Plant growing in cryptogamic mat on exposed site among rocks with occasional fireweed plants. Site on higher ground on the south facing side of the island. Baffin Island, Cape Dorset. 3 August. 2005. Aiken. No voucher. • Ground-level stems. Tiny High Arctic plants with well-developed stems covered with leaf bases that have broken off. A. Stem horizontal. B. Stem tending to vertical with four new leaves produced this growing season. By counting the number of leaf bases, one can estimate the age of the plant. Nunavut, Ellesmere Island, Lake Hazen. CAN 483324. • Habitat. Small fern plants growing on a turfy slope, under the shelter of a rock, near the sea. Nunavut, Baffin Island, Iqaluit, Apex area. 27 July, 1982. J.M. Gillett 19077. CAN. • Close-up of plants. Fragile fern growing in the shelter of rocks. Nunavut, Baffin Island, Ogac Lake. 9 July, 2004. Aiken and LeBlanc 04–215. CAN. • Baffin habitat. Lush plants growing among the rocks at the base of bird cliffs. Nunavut, Baffin Island, Iqaluit. 4 July, 2002. Aiken. No Voucher. • Leaves. Autumn leaves with mature spores. Spores of this specimen are rugose, i.e., the 'dickieana' type. Finland, Inarin lappi, Kevojoki. September, 1996. R. Elven. O. • Leaf with young sori. A. Lower surface of leaf pinnae showing each sorus covered with a whitish, scale-like indusium that falls early. B. Upper surface of the leaf pinnae. The leaf veins are not very visible, but the position of the underlying sori can be seen. Nunavut, Baffin Island, Nettilling Lake, Burwash Bay. CAN 518068. • Arctic Island Distribution.

This publication is available on the internet (posted May 2011) and on CD-ROM (published in 2007). These versions are identical in content, except that the errata page for CD-ROM is accessible on the main index page of the web version.

Recommended citation for the web-based version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. NRC Research Press, National Research Council of Canada, Ottawa. http://nature.ca/aaflora/data, accessed on DATE.

Recommended citation for the CD-ROM version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. [CD-ROM] NRC Research Press, National Research Council of Canada, Ottawa.