Cystopteris bulbifera

Bulblet Fern

Bulblet Fern, Photo courtesy USDA Plants Database
Bulblet Fern
Photo courtesy USDA Plants Database

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The natural history of the northwoods


  • Cystopteris, from the Greek, kustis (cystis), "bladder" and pteris (pteris), "fern", a reference to the inflated indusia of these ferns.
  • bulbifera,from the Greek, bolbos (bolbos), "bulbous root, bulb; onion", and the Latin, fero, "to bear"; hence, "bulb bearing".
  • Common name from the green bulblets that form on the underside of the fronds, dropping off to grow into new ferns.
  • Other common names include Berry Bladder Fern, Bladder Fern, Bulblet Bladder Fern, Bulblet Fragile Fern, Cystoptère Bulbifère (Qué)


  • Kingdom Plantae, the Plants
    • Division Polypodiophyta, the True Ferns
      • Class Filicopsida
        • Order Polypodiales
          • Family Dryopteridaceae, the Wood Ferns
            • Genus Cystopteris, the Bladder Ferns
  • Taxonomic Serial Number: 17481
  • Also known as Filix bulbifera, Polypodium bulbiferum


  • A small, deciduous fern of rock faces forming asymetric clumps, 12" to 30" tall.
  • Fronds monomorphic, seasonally bearing sori (earliest leaves lack sori, subsequent leaves with sori).
    • Petiole (leaf stalk) reddish when young, but usually green or straw-colored throughout (occasionally darker) in mature specimens; shorter than blade, base sparsely scaly.
    • Blade broadly to narrowly triangular, often with a stretched-out appearance, almost always widest at base. Thrice-cut and lacy with leaf ribs usually densely covered by hairs, often with bulblets.
    • Rachis (axis) usually densely covered with hairs, often with bulblets.
    • Pinnae (primary leaflets) mostly perpendicular to rachis, not curving toward blade tip, margins toothed.
    • Pinnules (secondary leaflets) sessile to short-stalked, veins directed into notches.
  • Rootstalk creeping, not cordlike, internodes very short, less than ¼", heavily beset with old petiole bases; hairs absent; scales brown.
  • Sori few and scattered, back from leaf edge.
    • Indusia cup-shaped, typically with hairs.
    • Spores spiny.


  • Identifiable as a Bladder Fern by thrice-cut, lacy fronds which are widest at the base.
  • WARNING: Cystopteris species are distinguished from one another with great difficulty and often not a little bit of frustration. The "distinguishing" characteristics are often difficult to identify clearly and there is a fair amount of overlap. That said:
    • Distinguished from Fragile Fern (Cystopteris fragilis), and Upland Brittle Bladder Fern (Cystopteris tenuis), by its characteristic bulblets, narrowly triangular fronds with stretched tips, and tiny hairs on leaflet stems.
    • Distinguished from St. Lawrence Bladder Fern, Cystopteris laurentiana by frond axis and leaflet ribs densely covered with hairs, by frequently bearing bulblets, and byall but the earliest fronds of the season bearing sori. The frond axis and leaflet ribs of St. Lawrence Bladder Fern is only sparsely covered with hairs, occasionally bearing bulblets (often misshapen), and nearly all leaves bear sori.
  • Field Marks
    • rocky habitat, especially rock faces
    • triangular fronds with stretched tips
    • tiny hairs on frond axis and leaflet ribs
    • bulblets on leaflet edges


  • Ontario to Newfoundland, south to Missouri, Arkansas, Texas, Alabama, and Georgia. Also Utah, Arizona, and New Mexico.


  • Cracks and ledges on moist, shaded cliffs and outcrops; usually on calcareous substrates
  • On rock in dense woods; occasionally on the ground in northern swamps.






  • By spore and vegetatively by rhizome.


  • By rhizome division
  • .


  • Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
  • Occasionally available by mail order from specialty suppliers.



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Last Updated on 26 February, 2004