The stem may be of two kinds—long, thin, and creeping, as in the common polypody, or short, stout, and upright, as in the common male fern.
At intervals along the creeping stem, or arranged more or less regularly around the crown of the erect stem, little buds appear, which eventually form the fronds which are the really conspicuous portion of the plant, and whose aspect is familiar to us all. The buds present a character of great interest and singularity. Instead of being simply folded together, as leaves generally are,—in all but two of our British kinds the fronds are rolled up after the fashion of a crosier or shepherd's crook. In divided fronds, the sections are rolled up first, and singly, and then the whole are rolled up again, as if forming but a single piece. The aspect of some of these young fronds—in the common bracken, for instance—with their many divisions all partially unrolled, is often highly curious.
But in this I am proceeding too far. The first crop of fronds, even in those kinds which when mature are most deeply cut, are usually very simple in form—almost or wholly undivided.
This fact is often a source of great confusion to beginners. I well remember two perplexities of the kind in which I was involved during the earlier season of my attention to this subject.
Growing upon a rock by the roadside, I found a small fern, more exquisitely beautiful than any I had seen before. I gathered and preserved it, but for many months was wholly puzzled as to its nature. Fancies arose that I was the happy discoverer of a new species,—and what if Professor Lindley or Sir William Hooker were to name it after me—Asplenium, or Polystichum, or something else, Meredithii? That would be better than a peerage.
These were but fancies, and I was well pleased when further experience—for books helped me not at all—showed that it was a young plant of the common lady-fern. It was divided once only—into simple leaflets—while the fully-developed frond of the matured plant is one of the most highly subdivided our islands can produce.
When I began collecting ferns, I had not seen a specimen of the rare holly-fern, and it was pardonable in me on finding some fronds which evidently belonged to the shield fern genus, and were divided into spiny leaflets only, to refer them to this species and tell a friend that I had made a great discovery. But on going to the same plant a year later, my mistake was made plain, as the new fronds were much more divided, and showed the plant to be of the common kind, the prickly shield-fern.
On the rocky sides of little Welsh and Highland rivers, in glens where the sunlight seldom enters, complete series of this fern in all its stages—from the tiny simple leaf to the deeply-cut and boldly-outlined frond of nearly three feet in length—may easily be obtained, and will beautifully illustrate its varied and increasingly-divided forms.
Some fronds of course, as those of the graceful hart's-tongue, are undivided even at maturity, except in occasional instances in which, like creatures endowed with more sentient life, they become erratic, and show a disposition to pass beyond the ordinary limitations. Curious examples of tendency to a greater than even their proper large amount of subdivision are occasionally shown in specimens of the lady-fern, which become forked at the extremities not only of the fronds but of the leaflets also.
The manner in which the fronds divide into lobes, segments, leaflets, and so on, is of course largely dependent upon the character of the veining, which differs widely from that of the flowering plants. In these, the veins are either netted or parallel, but in ferns they are forked, each branch again forking, and so on outward to the margin. This is only partially true of the scale-fern, and not true at all of the adder's-tongue; but it is the case with all other of our native kinds.