26

CRYPTOGAMIA.-FERNS.

hence spoken of as acotyledonous. On the other hand, of the Flowering-plants some possess one and others two cotyledons; and this difference in the structure of the seed is accompanied by so many other differences in the structure of the stems, the leaves, flowers, &c. that it serves to mark the two principal subdivisions of this portion of the Vegetable Kingdom. That in which only one cotyledon exists is termed Monocotyledonous; and that in which there are two, Dicotyledonous. The common Bean or Pea will serve as a characteristic illustration of the former; and the Wheat and other Grass-seeds, of the other.

1

22. The general aspect of the Flowering-plants is sufficiently well known to render a more minute account of them here unnecessary; since the object of this preliminary view of the Vegetable Kingdom is to render the student, who may have been previously entirely ignorant of the subject, prepared to enter with advantage on that detailed description of the mode in which the several tribes grow and reproduce themselves, which it is the object of the Physiological portion of this volume to communicate. A fuller sketch of the principal divisions of the Cryptogamia will, however, now be given, as few ordinary observers bestow much attention on them.

23. Of all the CRYPTOGAMIA, the Ferns approach most nearly to Flowering Plants. The general aspect of those inhabiting this and other temperate countries is well known. They present a small number of leaves,-generally much divided into leaflets, and these again often minutely subdivided,-each arising from the ground by a woody stalk, which is commonly regarded as the stem of the plant. The true stem, however, is buried beneath the ground, or sometimes creeps along its surface; and the branches it sends upwards into the air are really the leaf-stalks. (Fig. 1.) In many Ferns of tropical climates, the true stem rises upright, like that of a tree, and bears at the top a beautiful crown of those peculiarly graceful leaves for which the Ferns are remarkable. The height of these Tree Ferns, which are most luxuriant in the small islands, where they are furnished with a more regular supply of atmospheric moisture than they can obtain at a greater

distance from the sea, is sometimes as much as 40 or 45 feet; so that we must not judge of the whole race by the comparatively insignificant specimens which our own climate affords. These stems do not, however, afford any wood sufficiently solid to be employed in the arts. (Fig. 2.)

24. The organs of reproduction in Ferns have no evident analogy with the flowering system in higher plants. Nothing like a flower is ever seen in this group; and the fructification is incorporated, as it were, with the leaves,-being generally found, when mature, in brown spots or lines on their under surface or at their edges; the nature of the organs composing these will be hereafter described. In most Ferns, all the leaves are con

28

GENERAL CHARACTERS OF FERNS.

cerned in producing the fructification; but in some (of which the Osmunda regalis, or Flowering-Fern as it is commonly but incorrectly termed, is an example) certain leaves are devoted to the production of the fructification, and are termed fertile: whilst others only perform the usual functions of leaves, and are called sterile leaves, from the absence of reproductive power in them. The term frond is generally applied to the leafy portions of the Cryptogamia, as distinguishing them from the true leaves of Flowering Plants, which have only one set of offices to perform. Sometimes the fertile frond of Ferns altogether loses its leafy aspect, its edges being completely rolled in so as to inclose the fructification; and this separation of the reproductive from the nutritive portion of the system, is as complete as any which the Cryptogamia exhibit.

25. One of the most interesting peculiarities of the Ferns is the spiral mode in which its leaflets and leaves are rolled up before their first appearance; each leaflet being rolled up towards the rib which supports it,—the ribs again towards the midrib, and the midrib towards the footstalk. The unfolding leaves, in a state closely resembling those represented at the top of Figure 2, may constantly be seen during spring in spots frequented by this group; and, when examined, display the most provident and beautiful arrangement of the numerous minute parts of which the whole leaf consists. Few common objects, indeed, are more interesting than this, which requires neither skill nor the assistance of instruments for the detection of its beauties.

26. Although Ferns constitute but a comparatively small part of the present vegetation of this country, they must have been much more abundant in a former period of the earth's history, especially at the time when the beds of coal were being formed; since their remains now constitute by far the largest part of those which are preserved to us with tolerable perfection in a fossil state. This is partly due, however, to the remarkable power which these plants possess, of resisting the action of water; by which other plants and trees were decomposed,-their remains

GENERAL CHARACTERS OF MOSSES.

29

having contributed to form those immense masses of Coal, which are so important to man, not only for his personal comfort, but for the arts of life. The Ferns are able to withstand the effects of even a very prolonged immersion in water, with scarcely any change; whilst not only the soft tissue of plants, but the heartwood of most trees, decays so completely under the same circumstances as to leave little or no traces of their character. In tropical islands, the Ferns constitute a most important part of the whole vegetation; being equal in number, in the Sandwich islands, to one-fourth, and in Jamaica to one-ninth, of all the Flowering plants existing in each of these localities.

27. The next principal group of Cryptogamia, that of Mosses, is as interesting from the delicacy and minuteness of all the plants composing it, as other tribes of the Vegetable Kingdom are for the majesty of their forms, or the vast extension of their foliage. These are so generally and easily recognized as such, that a minute description of them is at present unnecessary; but it should be stated that the term Moss is commonly applied not only to the true Mosses, but also to many Lichens. The true Mosses, however, are always to be known by the green colour they possess except when dried up, while the Lichens are usually greyish in their

aspect. Mosses usually possess

a sort of stem, round which the minute leaves are arranged with great beauty and regularity; but neither this stem, nor the leaf-stalks of the leaves, have any truly woody structure; and they more closely resemble the simple tissue of the lowest plants, than the complex fabric of those already noticed, to which they seem to bear a greater resemblance in external form. Mosses do not, like

30

MOSSES. -MUNGO PARK.

Ferns, bear their fructification upon the leaves or modifications of them; it is inclosed in a little case or urn, which is furnished with a lid, and is borne on a long distinct stalk, so as to be very easily observed when full-grown. The interior of this minute organ usually contains a structure of great beauty, which will be hereafter described in detail; but it is interesting to know that it was by the contemplation of this that the heart of Mungo Park, the African traveller, was revived, when the difficulties by which he was surrounded had almost extinguished hope within him. The passage has been often quoted; but, it may be hoped, never without its use; and it does not seem superfluous to introduce it here.

28. This enterprising traveller, during one of his journeys into the interior of Africa, was cruelly stripped and robbed of all that he possessed by banditti. "In this forlorn and almost helpless condition," he says, "when the robbers had left me, I sat for some time looking around me with amazement and terror. Whichever way I turned, nothing appeared but danger and difficulty. I found myself in the midst of a vast wilderness, in the depth of the rainy season,-naked and alone,-surrounded by savage animals, and by men still more savage. I was five hundred miles from any European settlement. All these circumstances crowded at once upon my recollection; and I confess that my spirits began to fail me. I considered my fate as certain, and that I had no alternative but to lie down and perish. The influence of religion, however, aided and supported me. I reflected that no human prudence or foresight could possibly have averted my present sufferings. I was indeed a stranger in a strange land, yet I was still under the protecting eye of that Providence who has condescended to call himself the stranger's friend. At this moment, painful as my reflections were, the extraordinary beauty of a small Moss irresistibly caught my eye; and though the whole plant was not larger than the top of one of my fingers, I could not contemplate the delicate conformation of its roots, leaves, and fruit, without admiration. Can that Being (thought I) who planted, watered,