Cystopteris protrusa (Weath.) Blasdell - Lowland Brittle Fern, Southern Fragile Fern

Cystopteris protrusa plant

Family - Dryopteridaceae

Stems - Rhizomes scaly, horizontal, with fibrous roots, densely reddish-yellow pubescent, 3-4mm in diameter. Scales typically 5-6mm long.

Leaves - From 1-5cm behind the tip of the rhizome, densely clustered, narrowly lanceolate to oblong in outline, to +/-30cm long, 5-6cm broad. Petioles long (+/-15cm), darker brown at the base, greenish apically, with an adaxial groove, when cut transversely 2 vascular bundles are noticeable. Leaves 1-2 pinnate. Pinnae mostly alternate, at right angles to the rachis, typically bipinnatifid, glabrous, serrate.

Cystopteris protrusa frondFrond without the petiole.

Inflorescence - Sori originating from the lateral veins on the pinnae, globular, .3mm in diameter. The indusia originating from one side of the sorus, glabrous, small. Typically +/-15 sporangia per sorus.

Cystopteris protrusa soriSori on the abaxial surface of the pinnae

Flowering - Spores produced April - July.

Habitat - Mesic and bottomland forests, rich soils of slopes, ravine bottoms, streambanks, sinkhole bottoms.

Origin - Native to U.S.

Other info. - This springtime fern can be found throughout Missouri in the habitats mentioned above. It is the only member of its genus in Missouri to not grow from rock ledges or crevices. The plant typically wilts once the daytime temperatures start to really rise but plants can persist until late summer.

Photographs taken at the Dr. Frederick Marshall Conservation Area, Platte County, MO., 5-6-01.


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