Interrupted Fern (Osmunda claytoniana)


The Interrupted Fern (Osmunda claytoniana) is in the Royal Fern Family (Osmundaceae) and order Polypodiales. The order name is from the Greek for "many feet," probably referring to its rhizomic nature.

Ferns are easily recognized by the fronds that resemble a single-stem, compound leaf rising from a common base in the ground. The leaves on the frond of the Interrupted Fern are elliptical, deeply-toothed and arranged in opposite pairs. The lengths of the leaves become progressively shorter the higher they are on the stem.

Fronds of the Interrupted Fern are of two types: spore-bearing or sterile. The fronds of this plant are arranged in a vase-like arrangement with the spore-bearing fronds in the center and somewhat erect. The sterile fronds are on the outside and lean out from the center.

The brown spores are born on two to five pairs of pinnate leaves in the center of a spore-bearing frond. As seen in the photograph above, these leaves turn brown as the spores develop. Notice that the leaves above and below the spore-bearing leaves remain green and sterile. The spore-bearing leaves "interrupt" the spore-bearing fronds, whence the common name.

The root system is rhizomic.

The Interrupted Fern (Osmunda claytoniana) stabilizes the soil and filters water.

Different species of ferns can look very much alike but they can usually be differentiated by the arrangement of the leaves on the fronds, the distribution of the fronds and the character of the spore generation.

Ferns, including the Interrupted Fern, are frequently grown as ornamental plants. However, wild species should be left undisturbed because they become established slowly.

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