Because of their beauty, abundance and inherent interest, the ferns of this region occupy an important place in its botany. They lend an effect of almost tropical luxuriance, in places, to the forests of the lower Canadian zone where they are found in greatest abundance. However, they are, by no means, limited to this habitat. Some species may be found growing in the meager soils in or about talus slopes of the Hudsonian zone. Some anchor themselves in small niches in moist, moss-covered rocks at various altitudes, while others clothe the soils of open, sunny places - as in the case of the bracken which quickly attempts to rehabilitate burned areas in the forests of the northwest.
Nor is the interest in our ferns limited to the summer season. Certain species are evergreen and may be noted throughout the year. The most common of these evergreen ferns, which are native to Mount Rainier National Park, are the Sword Fern (Polystichum munitum) and the Deer Fern (Struthiopteris spicant) which are indigneous to the lower wooded Canadian zone forests.
Place of ferns in the organization of the plant kingdom.
In the systematic organization of the plant kingdom the various individuals that compose this broad, complex and important group are segregated with regard to certain basic characters and grouped into four main divisions.
I-Thallophytes: This group is composed of plants that have, in general, no well defined organs simulating roots, stem or leaves and which do not possess vascular tissue. In this group we find the most lowly of our plants, but it also exhibits great diversity of form, in the species which it contains, as can readily be noted from the fact that in the thallophytes we find the bacteria, algae, slime molds, diatoms, fungi and lichens.
II-Bryophytes: The mosses and liverworts compose this group. They are small, green plants of simple structures and while they may be differentiated into organs resembling roots, stem or leaves, true roots and vascular tissue are absent.
III-Pteridophytes: This group includes the ferns and fern allies. Here, too, we find a wide variety of form that is often confusing to the novice. Yet, while many of the plants contained do not outwardly appear to resemble ferns, as we generally understand that term, they all possess well defined characters by which they are grouped in this division. The Pteridophytes may be broadly classified as spore bearing plants which possess vascular tissue in leaves and stem and which are possessed of true root structures. It is with this division that this particular issue of Mount Rainier National Park "Nature Notes" deals.
IV-Spermatophytes: This group includes all the seed bearing plants. It is the highest of the four plant divisions and is the one that is, generally, best known and appreciated.
Thus briefly outlining the general characteristics of the four main divisions of the plant kingdom we indicate the relative position of the ferns with other common plants with which most people are familiar.
Number and diversity of ferns.
There are more than six thousand known species of ferns scattered throughout various parts of the world. They vary in size from hair-like, creeping stems bearing a few simple moss-like leaves to tall tree-like growths in the case of the tree ferns that are possessed of an erect single stem. Often this stem will be a foot or more in diameter and many feet in height, the foliage of the plant being borne in a whorl-like cluster at the top. At one time, before the seed bearing plants were evolved, ferns in all their variety of form were the dominant plant life. It is from them, laid down in the carboniferous period, that our present coal beds are derived. The average person can barely conceive of that remote era in the earth's past when vast forests of giant tree ferns grew in tangled abundance in the soggy, shaded marshes bordering the nucleii of present land areas as these rose slowly from the sea. However our coal fields are reminders of that time when ferns were the dominant plant life on the earth.
Thirty-three ferns and fern allies are listed as native to Mount Rainier National Park (see page 8). This group is characteristic of the diversity in form and appearance of the Pteridophytes, for therein we find not only plants of typical fern structure such as the bracken, sword fern and deer fern, but also others of radically different appearance - such as the Club Moss (Lycopodium), horsetails (Equisetum), Grape Fern (Botrichium) and Quilworts (Isoetes). These, while differing in outward appearance from those plants commonly regarded as ferns, nevertheless have the same basic characters by which they are united in a common division of the plant kingdom.
The growth and development of a fern.
Ferns, of course, are not flowering plants. Instead of possessing seeds, they reproduce by means of spores which, instead of developing directly into the fern plant that we see, produces an intermediate growth known as the prothallus (see page 4) That term was coined from the two Greek words which mean "before the shoot". Upon the underside of this prothallus are the sex organs. It is from this intermediate growth or prothallus, after the fertilization and development of the egg has taken place, that the fern that we see along the trail develops. This process is known as the alternation of generations and, as it requires the development of two distinctly different plants, it furnishes one of the most interesting features of fern study. Briefly the development of a fern may be traced in the following manner -
1. The ordinary fern plant (known as the sporophyte) serves merely to bear numerous spores which make their appearance in the early summer on the underside of the fronds and enclosed in light yellow or brown spores cases. If you will look at the underside of the fronds at the proper season you will notice these numerous brown "dots". Each one of these is composed of a considerable number of sporangia and the "dot" itself is known as a sorus.
2. Upon maturity the spore is discharged and, if favorable conditions are found, it develops into the sexual stage of the plant (the gametophyte) which we have previously termed the prothallus. This is a very small, obscure, thin, green heart-shaped plant, upon the underside of which are the sex organs (antheridia, the male and archegonia, the female) which correspond, in general function, to the stamens and pistil of the flowering plant.
3. Fertilization of the archegonia follows; the egg develops and the fern plant begins to grow. About seven years are required for a fern to develop from the spore to the stage when it is also a mature spore bearing organ.
In some cases ferns may propogate vegetatively - that is, by runners. Also, in a few cases the tips of the leaves may bend over to the earth and take root. There are no species of the latter type native to Mount Rainier National Park, however.
The early history of mankind and his attempt to fathom the apparent mysteries of plant life are replete with fanciful legends and tales that try to explain the development of plants with which he came in daily contact. Ferns were no exception to this rule. Before the compound microscope came into use, and thus before the steps by which the fern developed were understood by science, many theories that attempted to explain the origin of ferns were put forth. Students were aware that ferns bore no seeds - yet ferns continued to grow and develop. During the middle ages, ferns were supposed to have an invisible seed since it was thought necessary for all plants to have seed in order to grow, develop and reproduce. It is reputed that this invisible seed was greatly sought after by those who wished to make themselves invisible. This sort of tale was typical of the misunderstandings that existed in those times and which modern science and careful research has dissipated.
Ferns used for medicinal purposes.
Because of the magical powers that were attributed to ferns they naturally came into early use in medicine. Even as early as Nero's time, the bracken and several other species were used in the preparation of prescriptions for various ills. As time went on many ferns were gradually proven to be of little or no medicinal value. An exception is found in the Male fern which is sometimes used as a vermifuge (to expell worms from the body). It is interesting to note that it was used thus over 2000 years ago.
Thus ferns have captured the interest and fancy of the world for centuries. We known considerably more about them today and the knowledge that we have gained has made them of even greater interest to the student and the lover of the outdoors.
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