Although to most people the study of fossil botany may appear to be an uninviting pursuit, there can be no question as to the importance of the science. It is only in this way that we are able to appreciate the changes which have led up to the existing types of plants. Now the question of the past history of the Vascular Cryptogams is of very special interest in more ways than one. It is, of course, most fascinating to be able to discover what kinds of Ferns flourished, for instance, at the period when the coal deposits were being formed. But, even in a cursory description, it will be quite impossible to allow the matter to rest there. The story of the past, in the case of the Vascular Cryptogams, is closely interwoven with some of the most absorbing phases in the evolution of the Flowering Plants which are such a dominant feature on the earth at the present time. Quite recently we have had to alter our views materially on the matter of the past history of the Ferns. Within the last few years it has been proved that a huge number of the fossil remains, belonging to the PalÆozoic formation at any rate, are not Ferns at all. They belonged to a very distinct race of plants altogether, known Now the interesting point about these Ferns is that they were not vastly different, in many ways, from the species which exist on the earth at the present time. Of course certain types, of which we have living examples, were more fully represented than is the case nowadays; on the other hand, some of our most widely distributed families seem to have been at rather a low stage in their history. As well, the remains evidence a large number of very simple species, which perhaps give us an idea of what the original Ferns were like. But on the whole there is nothing to show that our living Ferns are any more developed than the highest types which grew in the coal forests. In these far-away times there were Tree Ferns; but so there are, of course, at the present time. The early botanists who strove to prove that Ferns were, so to speak, the last development before the Flowering Plants were not, perhaps, very far from the truth. It has been seen that during the period when the coal deposits were being formed there flourished side by side races of true Ferns and Fern-like plants which bore seeds—the Pteridosperms. The point has also been suggested that in all probability these two groups of plants had a common origin. With the coming of later times (the Cretaceous and Jurassic periods) there appeared the BennettiteÆ. These remarkable plants seem to have entirely taken the place of the Pteridosperms, and were an enormous advance towards the Flowering Plants of the present day. Only recently have the BennettiteÆ been properly described and their interesting features fully understood. We have a few representatives of this important group in the Cycads, plants bearing a superficial resemblance to Palms, but actually very different in all other ways. By the manner in which the reproductive organs are produced, and the way in which the scheme is carried out, these BennettiteÆ appear to be a half-way house between the cryptogams and the advanced flowering plants. The stamens bearing the pollen are produced on the fronds very much like the sporangia of Ferns. On the other hand, the seed-bearing structures are collected together into a sort of pistil. This was borne at the tip of the branches and ended their growth, just as happens in the case of Flowering Plants. For some reason which we cannot understand these BennettiteÆ seem to have fallen back in the race for supremacy, for the group is but poorly represented in our modern Cycads and a few allied plants. In all the world When we come to consider the past history of the Club Mosses the record is of a different nature to that of the Ferns. Nowadays the Club Mosses are not of great importance in the world, even though, as will be shown later, the number of species is considerable. But when we travel back to PalÆozoic times, particularly in the coal period, it is evident that these plants were represented by a number of very large and dominant families. Some of these early Club Mosses certainly came very near to rivalling the Flowering Plants. Probably the tendency of the world to become drier has had something to do with the decline, seeing that in all cases the fertilization is carried out under water. We may gather some idea of the importance of the Club Mosses in PalÆozoic times from the fact that in every part of the world where coal deposits have been examined great numbers of the fossil remains of these plants are always discovered. Many of these grew into large trees which were a hundred or more feet in height, sending out great branching shoots above and an enormous root system below. From a botanical point of view there is no doubt that some of the Club Mosses, particularly those belonging to the family SelaginellaceÆ, have approached very nearly to the Flowering Plants. At the present time the existing species, the Selaginellas, bring us up to the very threshold of the dominant group. The lowest division The Horsetails, like the Club Mosses, have had To complete our brief survey of the Vascular Cryptogams it is now necessary that we should review the position of these plants at the present time. Of course in number the Ferns are enormously in advance of all the other plants put together. In the whole world, there are not far short of seventy distinct genera, which include anything between three and four thousand species. The Ferns of the United Kingdom number not far short of fifty, and there are certain variations from the type which some folk are tempted to include as species. For some reasons which we cannot well understand, the Ferns alone amongst the Vascular Cryptogams have been able to hold their own in the world. It is probable that Luckily many kinds of Ferns are still very common in the United Kingdom. Of course, in much-visited localities the ravages of the trippers have practically exterminated some interesting species in these particular districts. Naturally, one hardly expects to find the Royal Fern flourishing to any extent in the popular holiday haunts—none the less, there are still As far as number is concerned, the living Club Mosses represent a comparatively insignificant group when compared with the Ferns. In all the world there are probably not more than five or six hundred species. These are very widely distributed, and there is hardly any part which cannot offer at least a few species. We have five species of Lycopodium in the United Kingdom. All are rather local, though often enough they occur in great abundance in special localities. Only one (Lycopodium inundatum) ever occurs in lowland districts; all the rest must be looked for on highland moors. A few exotic Lycopodiums grow to a fair size, though this is largely due to the fact that their creeping stems straggle along the ground for a considerable distance. The Selaginellas are a much more important group as far as the world generally is concerned. There are certainly as many as four or five hundred species, and some of these assume almost a shrubby habit. A species from Borneo (S. grandis) is said to attain the height of two feet. In the United Kingdom we have but a single species of Selaginella—S. spinosa, an insignificant little plant. Many exotic kinds are frequently grown in greenhouses, so that a Authorities vary as to the exact number of species which belong to the only genus of the Horsetail—Equisetum; the estimate is never higher than forty. Nearly all these plants are striking in appearance, and some are quite large. A tropical American species is said to attain the height of thirty feet, though this is not so remarkable when one considers that the plant has a climbing habit. In the United Kingdom we have at least eight distinct species. Some of these are exceedingly common, and owing to their vigorous growth will often hold their own against all comers. Indeed, the existing Horsetails are, to use a common expression, “putting up such a good fight” that it is certain they will continue to hold their own for many a long day. Unlike the Club Mosses, the Horsetails seem to be quite happy in the vicinity of towns, and are often seen at their best on railway embankments and in similar situations. Although the Vascular Cryptogams played an important part in helping to build up our vast stores of coal, it is astonishing to note of what little direct economic value they are to mankind at the present time. In a few parts of the world, where the native races make little or no attempt at agriculture, the root-stocks of Ferns—often rich in starch—are eaten. Thus the Maoris of New Zealand and some of the South Sea Islanders secure a poor kind of sago from some of the Tree Ferns which grow in their districts. The Japanese use the growing tips of the Bracken as food. Years ago, Ferns used to be burnt for potash in this country, and their astringent properties naturally attracted the old-world pharmacist. They are practically Coming to the Club Mosses, it is even more difficult to find that they are of any direct benefit. Some kinds in South America are said to yield a blue dye. Our Common Club Moss is in its huge quantity of spores responsible for the “Lycopodium Powder” which at one time was employed in the making of fireworks. The powder is said to be highly inflammable, but when shaken straight out of the cones it does not always ignite very readily. One of the Horsetails, the Dutch Rush (Equisetum hyemale), was—and perhaps is still—used in polishing, owing to the large amount of silica which is present in its stems. In addition, those who are interested in coast erosion say that the stronger-growing species of Equisetum should be planted to keep clay cliffs from falling. From an ornamental point of view the Ferns and some of the Club Mosses are, of course, of great value. They are widely cultivated in garden and greenhouse, and we may say that these plants make up in Æsthetic value what they lack from an economic point of view. |