Cystopteris bulbifera (Bulblet Fern)

Plant Info
Also known as: Bulblet Bladderfern, Bulblet Fragile Fern
Genus:Cystopteris
Family:Dryopteridaceae (Wood Fern)
Life cycle:perennial
Origin:native
Habitat:part shade, shade; moist rocky or peaty soil; shaded slopes, shaded banks, bluffs, talus slopes, swamps,
Fruiting season:mid-summer
Plant height:12 to 30 inches
Wetland Indicator Status:GP: FACW MW: FACW NCNE: FACW
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Fiddlehead:

[photo of fiddleheads] Fiddleheads appear in early spring on bright red to maroon stems sparsely covered in tiny, pale scales.

Leaves and stems: Leaf attachment: basal Leaf type: compound

[photo of early season frond] Leaves (fronds) are compound, narrowly triangular in outline, widest at the base, 4 to 24 inches long, 2 to 5 inches wide. The earliest fronds gradually taper to a pointed tip; later fronds are more elongated with a long taper to a slender tip (long-attenuate). Fronds have 18 to 25 pairs of branches (pinnae) that are more or less opposite, perpendicular to the stem, oblong to triangular in outline, tapering to a pointed tip, the lower pinnae with 10 or more pairs of lobes or leaflets (pinnules).

[photo of glands and veins on a mid-stem pinnule] Pinnules are irregularly toothed; pinnule veins are branched, sometimes forked, and terminate in the notches between teeth. The pinnule underside and the frond stalk (rachis) are variously covered in short-stalked glands, more densely so near the tip of the frond. Stems are grooved, the upper stem straw-colored to greenish on mature plants, the lower stem more brown or reddish. The plant grows in an asymmetrical clump, the fronds erect to ascending to arching. Old stem bases persist and some shriveled stems may persist to the next season.

Spores: Fruit type: spores_on_leaf

[photo of sori and bulblets] The sori (group of spores) mature in mid-summer and are found on the underside of the leaf. They are circular and arranged in a row along one or both sides of the pinnule midvein about halfway to the pinnule edge. A cup-shaped, translucent tissue (indusium) partly covers the spores, is attached on inner curve and is covered in glandular hairs. Spores ripen to dark brown or black. Larger round propagules (bulblets) also frequently form along the rachis and/or pinnae stalk (costae); these eventually fall off and form new plants. Not all leaves have spores or bulblets; the earliest leaves are mostly sterile and tend to be smaller than later leaves, which are mostly fertile.

Notes:

Bulblet Fern is common in moist forested areas of Minnesota, in the cracks and crevices of cliffs, on rocky slopes, moss-covered boulders, shaded banks, swamps and rock outcrops, often on calcareous substrates. It is probably the easiest of the Cystopteris species to identify: fronds widest at the base and most with a long taper to a slender tip (especially later in the season), veins terminate in the notches between lobes/teeth, pinnae undersides with scattered bulblets and variously covered in glandular hairs, more densely so near the tip of the frond. The bright red to maroon stems of young plants are also quite distinctive.

Cystopteris bulbifera is most similar to Cystopteris laurentiana, the child of C. bulbifera and C. fragilis, and C. tennesseensis, the child of C. bulbifera and C. protrusa. Both of these children have a shorter taper to the frond tip, more sparse glandular hairs on both the pinnae and indusia, veins that terminate in both the lobe notches and tips, and may have misshapen bulblets. C. laurentiana fronds are widest above the base and C. tennesseensis widest at or near the base; the latter also has smaller spores but a microscope is required to see this, and it hasn't been seen in Minnesota in at least 50 years so C. laurentiana is much more likely to be encountered. None of the other Cystopteris species in Minnesota (C. fragilis, C. protrusa, or C. tenuis) have any glandular hairs or bulblets and all have fronds widest at or just below the middle.

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More photos

Photos by K. Chayka taken in Goodhue County and in the garden. Photos by Peter M. Dziuk taken in Fillmore and Goodhue counties, and his garden.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: kate clover - Carpenter Nat. Center, Hastings
on: 2019-04-28 18:57:31

Found this fern on the limestone cliff along the rail grade hike at Carpenter Nature Center, Hastings. 4/19/19. Note the red color on the rachis/ stipes.

Posted by: Sherrie Hood - Big Bog, Waskish MN
on: 2020-08-07 21:14:22

Inconspicuous along the boardwalk along the bog on 8-5-20.

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