Cystopteris fragilis (L.) Bernh.
  • Neues J. Bot.
  • Brittle fern, fragile fern, cystoptère fragile

This taxon is accepted by Cystopteridaceae
Notes: More details could be found in The Plant List v.1.1. Originally in The Plant List v.1.0

General Description

Rhizomes shortly or long creeping, scaly at apex and stipe bases; scales brownish, broadly lanceolate. Fronds approximate or caespitose; fertile fronds (3.5-)20-35(-49) cm; stipe brown at base, upper part stramineous or chestnut-colored, usually shorter than lamina, nearly 1/3-2/3 as long as lamina, occasionally slender and slightly longer than lamina when plant in crevices, 5-14(-20) cm, (0.2-)1-1.5 mm in diam., with sparse, shiny scales; lamina usually 2-pinnate to 2-pinnate-pinnatifid, occasionally pinnate or 3-pinnate, lanceolate to broadly lanceolate, 17-28 × (0.8-)4-5(-8) cm, shortly acuminate at apex; pinnae 12-15 pairs, ascending, basal 1 or 2 pairs slightly shortened, or nearly not shortened, ovate to ovate-lanceolate, (0.4-)2-4(-7) × (0.2-)1-2.5 cm, obtuse or shortly acuminate, toothed at apex, subopposite, subsessile, widely separated from each other, usually 1-2 × as long as wide, 1.5-4.5 cm apart, base parallel to rachis on acroscopic side, ± cuneate on basiscopic side; pinnules 5-7 pairs, ovate or oblong, acroscopic side truncate, basiscopic side cuneate at base, sessile or shortly stalked, entire or toothed at margin, or pinnatifid, rounded or obtuse and toothed at apex; middle pinnae similar to lower pinnae, but slightly longer, separated from each other by 1.2-2.5 cm, subopposite or alternate, subsessile; upper pinnae pinnatipartite, toothed only on apices and acroscopic margin; veins pinnate, costules slightly tortuous, terminating in entire teeth. Lamina herbaceous when dried, green or yellow-green. Rachis and costae, especially their bases, ± with sparse unicellular to long multicellular hairs, even with few scale hairs. Sori small, orbicular, medial on veins, 2-4 pairs per pinnule, 1 or 2 sori at acroscopic side in upper pinnules; indusia pale green or brownish, ovate to lanceolate, membranous. Spores dark brown, perispore surface with regular, denser spines. 2n = 84*, 168, 252, 336.

Stems creeping, not cordlike, internodes short, beset with old petiole bases, hairs absent; scales tan to light brown, lanceolate, radial walls thin, luminae tan. Leaves monomorphic, clustered at stem apex, to 40 cm, nearly all bearing sori. Petiole dark at base, mostly green to straw-colored distally, shorter than or nearly equaling blade, base sparsely scaly. Blade lanceolate to narrowly elliptic, 1(--2)-pinnate-pinnatifid, widest at or just below middle, apex acute; rachis and costae lacking gland-tipped hairs or bulblets; axils of pinnae lacking multicellular, gland-tipped hairs. Pinnae usually perpendicular to rachis, not curving toward blade apex, margins serrate to sharply dentate; proximal pinnae pinnatifid to pinnate-pinnatifid, ± equilateral, basiscopic pinnules not enlarged; basal basiscopic pinnules sessile, base truncate to obtuse, distal pinnae deltate to ovate. Veins directed mostly into teeth. Indusia ovate to lanceolate, without gland-tipped hairs. Spores spiny or verrucate, usually 39--60 µm. 2 n = 168, 252.

Cystopteris fragilis (L.) Bernh., Neues J. Bot. 1(2): 27. 1805; Polypodium fragile L. Fig. 40 A–C.

Rizoma compac­to, cortamente rastrero, 2–4 mm de diámetro, con escamas lanceoladas, enteras, café lustrosas; hojas fasciculadas, 2-pinnadas a 3-pinnado-pinnatífidas, hasta 50 cm de largo, pecíolo en sección transversal con dos haces vasculares; lámina ovado-lanceolada, hasta 35 cm de largo y 15 cm de ancho, herbácea, opaca, con 1 ó 2 pares de pinnas proximales algo reducidas; raquis glabro o con tricomas glandu­lares; pinnas 7–17 pares, 1–4 cm de largo; últimos seg­men­tos oblongos; nervios libres, terminando en dientes o en pequeñas emarginaciones; soros redon­dos, indusio apicalmente subentero o lacerado, glabro.

Nebliselvas, bosques de pino-encinos o bosques secos; Williams 23898; 1500 m; norte y oeste de Norte América hasta Chile  y Brasil, Antillas Mayores e Islas Juan Fernán­dez, Europa, áfrica, Asia y Hawaii. Esta especie crece en poblaciones grandes, sobre taludes, rocas o pare­des húmedas. Sus poblaciones presentan gran varia­ción feno­típica, a veces crece en poblaciones mixtas con especies de Adiantum o de Anogramma. EN

"Lvs glabrous or inconspicuously glandular, in a small cluster on a short, densely scaly rhizome, 0.5–3.5(–4) dm, the dark brown (or distally greenish) petiole shorter than or to as long as the blade; blade mostly 3.5–20(–25) × 1.5–8 cm, (2–)2.5–4(–5) times as long as wide, 2–3 times pinnate, with 8–18 pairs of pinnae (the members of a pair often offset, especially the distal pairs), the lowest pair equaling or generally a little smaller than the next pair, the upper ones gradually reduced so that the blade tapers into a narrow tip; veins typically directed to the teeth of the pinnules, but the tooth sometimes apically slightly indented so that the vein ends in a small sinus; indusium pale, not glandular; 2n=188 in ours. Moist, mostly wooded slopes and ledges in circumneutral soil; circumboreal, s. in our range to Va. and Mo. We have 2 vars. with widely overlapping distribution:"


Common Names

Brittle fern, fragile fern, cystoptère fragile


 Information From

World Flora Online Data. 2017.
  • A CC0 1.0 Universal (CC0 1.0).
New York Botanical Garden
Descriptions of plants should be attributed to the full citation for each individual article, chapter or book that is the source for each record, which should include the authors of original publication.
  • B Content licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
Flora Of CHina @
'Flora of China @ eFloras (2008). Published on the Internet [accessed August 2016]' Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
  • C Missouri Botanical Garden
Flora of North America @
'Flora of North America @ eFloras (2008). Published on the Internet [accessed August 2016]' Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
  • D Flora of North America Association
Flora de Nicaragua
WD Stevens, CU Ulloa, A Pool and OM Montiel. Missouri Botanical Garden Press, 2001
  • E Missouri Botanical Garden
World Flora Online consortium
World Flora Online Data. 2018.
  • F CC0 1.0 Universal (CC0 1.0).