This is a very attractive Fern, and perhaps the only British species which frequently grows in water. The Marsh Buckler Fern has a creeping rhizome from which arise the fronds at intervals; these are of two kinds, barren and fertile. The barren fronds sometimes reach the length of four feet, the stipes—which is slender and of a pale green colour—being about equal to the leafy portion. The fertile fronds are usually shorter. In both cases the outline of the fronds is the same, being lanceolate. In each case, too, the pinnæ arranged alternately on either side of the rachis are cut almost to the midrib. In the case of the fertile fronds the pinnæ are perhaps a little more contracted; also the margins are inclined to bend over in such a way as to protect the sori. The clusters of sporangia are almost circular, and these are borne on the margins of the lobes on the underside of the pinnæ. The clusters of the sporangia are covered with small indusia which are slightly notched. The indusia are soon thrown off when the spore cases start to develop.
The Marsh Buckler Fern is not uncommon, and in suitably moist positions is often very abundant. It is, however, said to be rare in Scotland. The species will not flourish in a garden unless something in the way of a bog can be provided. The fronds appear in the spring and are cut down by the first frost.
Nephrodium oreopteris. The specific name is connected with the Greek word oros, “a mountain.” In some books this fern is also called N. montana and Lastrea montana. In certain districts, varieties of the species are common. The Mountain Buckler Fern.
In certain respects this species bears a resemblance to the Male Fern. The fronds spring from a tufted root-stock and their outline is lanceolate; they are from one to four feet in length. The foliage of the Mountain Buckler Fern is of a pale green colour. A distinctive feature is the manner in which the frond of this Fern tapers to a point at both ends; this is even more pronounced at the base than at the apex. In the Male Fern any tapering at the base is of a very slight description. The Mountain Buckler Fern is once pinnate, the pinnæ being continued almost through the entire length of the stalk; this makes the stipes very short. The pinnæ, which are generally placed opposite to one another, are cut very deeply.
Nephrodium oreopteris. The Mountain Buckler Fern.
The sori are much more abundant on the upper portion of the frond; we shall find them on the back of the leaf along the margins of the lobes. They are covered by a very slight indusium, which soon falls off. In the Mountain Buckler Fern there are to be detected a number of tiny glands on the back of the frond; these are responsible for rather a pleasant odour when the foliage is passed through the hand.
Back of frond of a typical Nephrodium. Enlarged.
The Mountain Buckler Fern grows on heaths, and it has been found in almost all parts of the United Kingdom. In certain parts of Scotland it is said to clothe the mountain sides with a wonderfully vigorous growth. It is not, however, as its name seems to imply, strictly a mountain species; for it often grows in lowland districts. In cultivation, the species should be given a moist situation. The Mountain Buckler Fern dies down in the winter and the new fronds appear in the spring.