Fiddlehead:

Fiddleheads appear in early spring on bright red to maroon stems sparsely covered in tiny, pale scales.

Leaves and stems:

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).

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:

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.