Cystopteris protrusa (Weath.) Blasdell

Lowland Brittle Fern


CC = 5
CW = 0
MOC = 84

© SRTurner

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.


© DETenaglia

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.


© DETenaglia

Flowering - Spores produced April - July.

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

Origin - Native to the 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 (DETenaglia); also along the Katy Trail near Treloar, Warren County, MO, 4-22-2022 (SRTurner).