Flowerless plants : how and where they grow

Preface

There are few more encouraging signs at the present time than the widespread interest in Nature Study. The age in which we live is an intensely practical one. Whatever our calling may be, it is likely that the majority of us spend most of our time in the keen pursuit of a professional or business career. The crowded days leave little space for that quiet reflection in which alone the spirit can find refreshment. It is surely, then, a matter for congratulation that there is an increasing tendency to turn to the satisfying joys which are waiting for everyone who cares to take up the wonderful book of Nature. Herein the tired man and woman will find an enchanting story, old as the earth itself, and yet ever fresh in its power to charm away the dull cares of a workaday world.

In spite of the large number of Nature Study books which are available at the present time, there are still many subjects which have been scarcely discussed from the ordinary person’s point of view. The important division popu-

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IV

PREFACE larly known as the Flowerless Plants is an excellent instance. Of course, there are plenty of admirable books dealing with the various groups of these interesting plants ; but it is to be feared that many of them can make little appeal to the general reader. Invaluable as works of reference for the more advanced student, they impress the beginner with the idea that the subject under discussion is decidedly dull. Now, whatever Nature may be, she is never dull ; all her doings are so full of vitality that the most indifferent can hardly fail to be impressed. In the textbooks of the specialists the interesting facts are all there, but they are often completely buried in technical phraseology. It would seem, then, to be the first duty of the writer of a Nature Study book for beginners to emphasise the attractive features in the life histories with which he has to deal. He will do this, feeling confident that when once a genuine interest is aroused the student will have entered for ever the charmed circle of those who worship at the shrine of Nature.

It is in some such spirit that the author has undertaken the present volume. If the reader cares to peruse the book to the end he will have scarcely advanced beyond the threshold of a very important matter ; yet it

PREFACE

V is to be hoped that what he has read will be sufficient to kindle in him a desire to know more about the Flowerless Plants and all that appertains to these singular groups. Then, indeed, will he find that the textbooks of the specialists are the best possible friends, incomplete in themselves, but priceless as guides to those things which alone can be truly studied in the open air.

S. Leonard Bastin.

Lyndhurst, 1913.

Contents

CHAPTER PAGE

1. A General Survey i

6. The Strange Story of the Lichens . . 105

Chapter II

Few of our native plants call forth such universal admiration as the graceful members of the fern tribe, and it is quite certain that it would be impossible to find subjects which present a more fascinating life history. Early observers were much perplexed as to the manner in which the reproduction of the fern was carried out. In some way they connected the brown scaly substance on the backs of the leaves with the increase of the kind, but of seeds there was none to be found, and the fern plants seemed to arise spontaneously from the soil. Modern research has dispelled most of the mysteries which surround the story of the fern, and we may now follow the marvellous process by which the new plant comes into the world from start to finish. Yet, even though our knowledge on these matters is now fairly complete, a description of the process is much more than a mere recital of facts. Right from the beginning, when the spore — a tiny speck of life — first of all appears on the scene, until the final unfolding of the mature plant, there is a strong element of romance such as is not by any means always present in a scientific record.

It is not easy to give a decided opinion on the real position of ferns in ancient times. It was formerly considered that a large number of the fossil remains now classed as BennettitecB were true ferns. As we have seen in the previous chapter, these really represent a very distinct type. When we consider the conditions, atmospheric and otherwise, of the steamy coal forests, it is likely that ferns very similar to those on the earth at the present time were strongly represented. With club mosses and horsetails they must surely have been a leading feature of the vegetation at that period. Many of the non-flowering plants are mere masses of cellular tissue, but the ferns are very striking in their manner of growth. Moreover, as in the case of flowering species, these plants have roots, stems and leaves in a well defined sense. Several of our native ferns grow into large plants which, on account of their size alone, would attract a good deal of

THE MALE FERN {yiphrodlum fiUx-mas.

attention. Of these the Bracken, the handsome Royal Fern, and the very common Male Fern are good examples. In some parts of the world, as we have already seen, ferns grow into tall trees with woody trunks.

Even though the group is such a large one, it would seem that the fern tribe have failed to maintain their former standing in the world. This appears to be due to an extent to their apparent inability to adapt themselves to changing conditions. By far the greater number of ferns cannot live save in very moist conditions, atmospheric and otherwise ; as we have seen, they throve to perfection in the saturated atmosphere of the Carboniferous Period and formed a dominating race of the peculiar vegetation of the time. Nowadays there are few parts of the world where ferns occupy such a position in the plant life of the country, save, perhaps, in New Zealand, and some islands in the southern seas. Curiously enough, almost the only ferns which are very general in the world at the present time are the few kinds which are not so dependent upon moist conditions. Of this there is no better example than the Bracken Fern, which occurs in Europe,

Asia, parts of America, and throughout the southern hemisphere. Of course, one can hardly say that the species is identical in character throughout the world ; slight variations do occur, but to all intents and purposes the plant is the same which grows so abundantly in this country. In Britain we may, of course, find the Bracken equally at home on the open hillside or under the dense shade of the forest trees ; in both situations it seems to prosper amazingly.

For the purpose of our study of the life history of the fern we can hardly do better than take an example of the Male Fern (Nephrodium filix-mas). This plant is not only a common wild species, but is also very largely to be met with in gardens, a circumstance which does not apply in the case of the Bracken — not an easy subject to cultivate. So familiar are most people with the Male Fern that a detailed description is scarcely necessary. The leaves of the plant are very variable and may very well be four or five inches in height or, in fine examples, as many feet. The stem is thick, and, in the case of old examples which have been left undisturbed for many years.

A COLONY OF LITTLE MALE FERNS may assume a trunk-like nature. It is covered with a chaffy material, and is also well adorned with the remains of leaf stalks. The Male Fern is deciduous in habit, although its leaves will quite often stand through the winter in sheltered places. If a leaf stalk is pulled away it will be noticed that the roots adhere to its base, and not, as might be expected, to the stump-like stem. As will be seen later, this is a feature which is to be observed in the case of other species of ferns.

An examination of the developing fronds in the month of April is particularly recommended. These have been in preparation for two or three years, and succeeding generations may be discovered inside the circle. How beautifully the opening leaves are coiled, and in what a thorough manner the young growth is protected with the brown chaffy deposit ! This doubtless plays a part in preventing loss of heat and moisture. Should the weather be wnrm the development of these ferns will proceed at a very rapid rate, and if the plant is visited at weekly intervals it will scarcely be recognised from one time to another.

With the maturity of the fronds of the Male

Fern it is noticed that the backs of the leaves are freely covered with brown patches. It is very easy to see that these spots are kidney-shaped, and on examination with a lens it will be found that they represent mere scales covering a number of tiny stalked bodies. This will be clearly seen if a magnifying glass is used, but under a microscope the true nature of the brown patches will be even more plain. The botanist calls each patch on the fern frond a sorus, whilst the stalked bodies are known as sporangia. Of course, these latter contain the spores by means of which the fern plant is reproduced. As soon as the spores are ripe the covering shrivels up and the spore cases burst open. The sudden opening of the sporangium is brought about by reason of the fact that, when ripe, a row of hard cells which occupy about three-quarters of its length acts like a spring, tearing apart the walls of the case. Thus the spores inside are thrown out into the world, and, being very light, float away on the breezes.

A spore, which is infinitely more simple than any seed, has never, perhaps, been better described than as a tiny spot of living matter ;

THE SPORANGIA OF A FERN

An enlarged view showing the little cases which contain the spores

A FERN SPORANGIUM ( Enlarged )

A MUCH ENLARGED SPORANGIUM

In the act of bursting to expel the spores

BABY FERN WITH PROTHALLUS

(Slightly larger than life size)

individually these specks are quite invisible to the naked eye, although collectively they appear like so much dust on a piece of white paper. One is amazed at the gigantic number of spores which each one of our fern fronds will produce. Every sporangium, it is computed, will be responsible for, perhaps, fifty spores ; each tiny sub-division of the leaf will bear quite this number of sporangia, whilst the tapering leaflets at the side of the stalk may carry thirty or forty fertile sub-divisions. Thus every leaflet on the fern frond, bearing spores at all, may produce quite one hundred thousand spores, and the total spore output of each frond must be many millions of spores. Truly a prodigious total ! Yet the world is not overrun with Male Ferns, although every spore produced is capable of giving rise to a specimen. Of course, a very large number of the spores are completely lost, owing to the unfavourable situations in which they alight.

The very best thing that can happen to the spore is that it shall settle down in some moist shady place. Here, after an interval, the tiny speck of life begins to develop, not into a mature fern, but into a flat green scale which has been called the prothallus. As a rule this process will be about half-an-inch, or something less, in diameter, though it may vary a good deal in the different species of ferns. If we hunt on the moist banks of a hedge round mature fern plants in the autumn, we shall almost certainly find a number of these green scales. An even more easy way to study the development of the prothallus will be to secure a packet of spores from some seedsman (or these may be collected from fronds), scatter them on moist soil, and keep the whole surface closely covered with a tumbler. It is advisable to sterilise the soil in the first instance by baking it in an oven in order to check fungus pests. A close examination of the prothallus will show that it is secured to the soil by delicate root-hairs, and that it is of a very thin texture, quickly shrivelling on exposure to a dry air.

The succeeding stages in the development of the fern plant cannot be followed with the unaided vision. With a powerful hand-lens, or, better still, of course, a microscope, a close examination of the underside of the prothallus will reveal the presence of certain special cells in addition to the root-hairs which have already

THE UNDERGROUND STEM OF THE BRACKEN FERN

In the foremost part of the shoot are to be found the buds for two years ahead

THE BRACKEN FERN. SHOWING FRONDS been mentioned. One group of these, that near the lower part of the prothallus, amongst the root-hairs, which in the case of the Male Fern is somewhat heart-shaped, represents the antheridia, or male cells. The collection of bodies near the upper portion of the prothallus are the archegonia, or the female cells of the system. The actual fertilisation of the female organs will take place when there is plenty of moisture surrounding the prothallus, such as might be caused by rain or dew. At such times the cells open, and the male organs discharge strange little spirally curved bodies— the spermatozoids. These, passing through the watery element, impelled by some motive which has given rise to a great deal of speculation, make their way to the female organs, enter the neck, and so complete the act of fertilisation. It is now generally believed that the explanation of the unerring movements of the male bodies lies in the circumstance that they are attracted towards the female cells on account of a certain substance which is given out from the archegonia at this time. As a rule only one archegonium on each prothallus is fertilised.

It is not very long before the new fern plant appears on the scene, at first in the form of a tiny bud, relying for its nutriment upon the prothallus which bears it. Later on the baby plant starts to send down a root into the soil, a little leaf is sent upwards, and from thenceforward it begins to lead an independent existence. Gradually the prothallus withers up, its purpose in life having been fulfilled.

The abundance of the Bracken Fern {Pteris aquilina) justifies a few remarks on the life-story of the plant. The general appearance of this fern is well known. The great frond varies much in size, and may well be less than a foot high in exposed places, or as much as three yards in shady situations. The foliage of the Bracken dies down during the winter, and the new shoots usually appear during the month of April. These are a pretty pale green, and quite often are tipped with old gold. The leaf stalks arise from a stout creeping stem, or rhizome, which throws out a plentiful amount of fibrous roots, chiefly produced under the leaves. In a sandy place it is not a difficult matter to dig up a portion of the root-stock, and this is worth an examination. The leaf stalks are seen to arise from each side of the stem, and going

back from the one, or possibly two, leaves which have been produced during the present season, we shall find the remnants of leaf stalks which have served during past years. If the stem is followed up in this direction we shall finally come to a place where it is rotting ; as a matter of fact this process of decay is almost keeping pace with the active extensions which are going on at the growing point. Beyond this year’s leaf it will be possible to find the buds for next year, and even the season after that. Thus should any accident happen to the developing leaf of the present season there will be another in a fairly advanced state to take its place. The root system of the Bracken is constantly extending, seeing that buds of new stems are continually being produced at the bases of the leaf stalks. This explains the wonderful way in which the fern captures situations. Indeed, it is very likely that, should all the land in the United Kingdom become uncultivated, it would not be many years before the Bracken Fern had claimed the major part for its own.

So complete is the arrangement for the increase of the Bracken Fern by means of its underground stems that propagation through the agency of spores is uncommon, at any rate in exposed situations. Spores are, however, pretty freely produced in stalked cases which are developed round the edges of the leaflets ; these are curved inwards in such a way that a groove is formed. During the late summer the spores are released in great numbers, sufliciently so at times to coat surrounding objects with a brown powder. The subsequent development of the spore consists in the formation of a frothallus with sex organs which were observed in the case of the Male Fern. For most people the best chance of watching the development of the new Bracken Fern from the spores consists in growing them on the lines suggested in the case of the Male Fern. It is curious to note that the underground habit of the plant does not at once become apparent. It is only after the production of a number of the leaves that the stem divides into two branches which grow downwards into the soil, whence they never again come up to the light.

A number of species of ferns which are more or less common in Great Britain and Ireland show certain distinguishing features. The Lady rue-leaved SPLEENWORT {Aspicnlun, rn/„.„noar/..)

A typical wall species

Fern (Athryium filix-fcBmina) bears a general resemblance to the Male Fern, save that it is a paler green and of an altogether more delicate growth. The manner of spore production is on somewhat similar lines to that of the Male Fern, though there are certain small differences. One of the chief of these is that the covering of the spore mass in the sporangium is fixed at one side, instead of in the middle, as in the case of the Male Fern.

Many of the ferns are well able to exist in dry situations. The Black Maidenhair Spleenwort [Asplenium adiantum nigrum) is a widely distributed species which is always distinctive by reason of its black stalks. This fern seems to be quite happy growing on the top of a wall or in the cleft of a rock. The sori, or clusters of sporangia, are elongated in shape, and are covered with a very pale green or white scale, during the early stages of development. After a while, however, the spore cases commence to swell, burst through the covering, and fill up the spaces between the clusters, so that eventually the back of the frond may appear to be entirely covered with the deep browm cases. The Rue-leaved Spleenwort [A. ruta muraria) is another species, a common enough kind on walls, but very often overlooked on account of its small size. The root-stock of this plant is often tightly pressed between bricks or pieces of rock, from which arise a number of small fronds, sometimes only an inch or so in length. As in the case of the Black Spleenwort, the spore cases, when becoming ripe, swell up so that the whole underside of the leaf is covered with the brown masses. This very much adds to the appearance of the handsome green leaves.

The Scaly Spleenwort {A. ceterach) is remarkable for the manner in which the fronds are protected on the underside with an abundance of rust-coloured scales. There is little doubt that these play a part in protecting the foliage against undue loss of moisture, a danger which is very real in the case of wall plants. As well in dry weather the whole leaf rolls up, so that most people might fancy that the fern was dead. With the coming of moist weather the normal habit of growth is resumed. The spore cases which are clustered on the underside of the leaf have little in the way of a special protecting scale, on account of the abundant covering already mentioned.

MAIDENHAIR SPLEENWORT Aspkuium t richow.DicA

THE H ART’S-TONGUE {Scolof>c>u{riunt ■t'ul^are)

Showing the curious arrangement of the sort

It may, perhaps, be well to mention that all these spleenworts vary very much in size according to the situation in which they are growing. On damp walls or rocky hedgerows, where there is an abundance of moisture, the size of the frond is much greater than when the plants are in dry places.

Many species of ferns show a very distinctive manner of producing their spore cases. Everybody is familiar with the common Hart’s- tongue (S colop endrium vulgar e) . The plant is, of course, exceedingly variable (several hundred different kinds have been identified), but its main points are fairly stable. The chief characteristic of the leaf is its undivided form, in outline generally tongue-shaped and tapering to a fine point. The spore cases are usually confined to the upper two-thirds of the back of the leaf, and have been likened to a number of long brown caterpillars. The clusters are placed on the veins of the leaf, and are usually at a distance of about one-eighth of an inch from each other. Each actually consists of two clusters of spores, and is covered when young with a thin white scale. This is, of course, thrown aside when the spore cases ripen.

A few species of ferns produce their spores on parts of the leaves which are specially reserved for this purpose, or on altogether different fronds. In the former class must be included the magnificent Royal Fern [Osmunda regalis), a plant which, owing to the depredations of trippers, is far less common than was formerly the case. It is still, however, abundant in some of the out-of-the-way parts of the kingdom. In a moist place the Royal Fern may frequently be found with its leaves eight or ten feet in height, and with many of the fronds the upper leaflets are entirely devoted to the business of spore production. On this account the plant is very widely known as “ the flowering fern.” An examination of the “ flowering ” portion will show that here the leaflets are very much contracted and bear upon their borders clusters of spore cases, which are usually so abundant as to give to the divisions a uniformly brown appearance. Under a magnifying glass it will be seen that the spore cases are stalked and globular in form.

Two kinds of fern which are not so familiar as they might be if people were only more observant are the Moonwort {Botrychium iW

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THE BLACK MAIDENHAIR SPLEENWORT THE MOONWORT {.noirychhnu hn,nr!„

lunaria) and the Adder’ s-tongue {Ophioglossum vulgatum). In both these cases the leaves are very decidedly divided into two parts ; the business of one portion is that of an ordinary frond, whilst the other section is concerned with spore production. These ferns are chiefly to be found growing amongst grass ; the Moonwort seems to prefer a somewhat drier situation than that favoured by the Adder’ stongue. A very careful search will be necessary to find them, however, as they seem to blend to a striking extent with the surrounding vegetation. The frond of the Moonwort usually appears about the month of April, and at a certain distance from. the root-stock it divides into two stems, one barren and the other fertile. The barren frond develops into curious sections shaped something like half - moons, whilst in the case of the fertile stalk there are produced divisions bearing clusters of spore cases, which, when ripe, are red brown in colour. The Moonwort sends up but a single leaf each year, and by cutting open the base of the stalk it is possible to discover the frond for the next season, and within this even the leaf for the third year may be discerned.

Much the same kind of thing occurs in the case of the Adder’s-tongue. Here, again, we may observe the curious double frond, which is divided into a fertile and a barren portion. The barren portion of the frond is not divided at all, but is of a simple egg-shaped design. The fertile division runs up into a kind of spike, at the upper part of which the spore cases are arranged in a double row. In both these strange ferns the leaves only last for a few months and usually die right down, the nutriment passing into the little root.

In the case of the Hard Fern [Lomaria spicant) the fertile fronds are quite distinct from the ordinary leaves. The barren leaves, which vary very much in length according to the amount of moisture which the plant is able to secure, are remarkable for the neat arrangement of the leaflets, not, as at first appears, in opposite pairs, but actually in alternation. The fertile fronds are usually much taUer and a good deal more erect in habit. There is a marked contraction of the leaflets, which are really very narrow, and bear on each side of the mid-veins clusters of spore cases. When these are fully ripe, however, they cover in almost the whole

THE HARD FERN (/. 'maria sph ani)

THE ADDER’S TONGUE THE POLYPODY . .v/i.,/;, )

One frond is turned so as to show the round ,< of the underside of the leaflet. In their early days the spore cases are covered with a protecting scale.

After all, it is likely that one of the most familiar ferns is the common Polypody [Polypodium vulgar e). This plant is very happy in many situations, but it is really most at home on the trunks and branches of old trees, especially oaks. The creeping stem, from which the leaves arise at regular intervals, pushes its way in and out through any leaf mould which may have accumulated. The stem is fleshy, and stands the plant in good stead during very dry weather, when, often enough, the shrivelled appearance of the fronds make it appear that the Polypody is dead. A few showers of rain soon revive the foliage, which is evergreen in habit. The spore cases are chiefly confined to the upper part of the leaf, and these are arranged in clusters on either side of the midrib of the sub-divisions. When in a ripe state the groups are often very closely set, so that a good deal of the back of the frond will appear to be covered with an orange-coloured coating. This often gives a very attractive appearance to the leaves of the Polypody. For its supply of moisture the Polypody must needs rely to a considerable extent upon that which it can secure from the atmosphere. In some ways, therefore, it strongly resembles the curious epiphytes of the tropical forests.

It may be the good fortune of the traveller in rocky districts to come across one or other of the dainty species of filmy fern. Wherever there are rocks, which from some cause or another are maintained in a moist condition at all times, there one may hopefully look for the Tunbridge Filmy Fern {Hymenophyllum tunhridgense) or the One-Sided Filmy Fern {H, unilaterale). These ferns are very similar in appearance, the chief distinguishing feature being that in the latter plant the fronds are much narrower than is the case in the first named. One is at once struck by the semitransparent nature of the little fronds, which rise from wiry rootlets, often so closely interwoven as to form a great mat, which may well be several yards square. The spore cases are borne in cup-shaped scales on the backs of the frond, and should be examined with the aid of a magnifying glass.

All those who really love ferns will resist

THE SCALY SPLEENWORT (As leniinu cctcrach)

Usually to be found grrowing; on old walls

THE TUNBRIDGE FILMY FERN (! lyiiit'iiof>hyllui)i 'rinthriiigcnsc)

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- y k - the temptation to tear up masses of the attractive fronds, seeing that these species could never be cultivated in an ordinary garden. Indeed, with all ferns it is a wise rule to refrain from uprooting unless one has a very good place in which to put the specimens. Even then only very small portions should be secured, and if the species is a real rarity, the genuine student will not feel it a sacrifice to leave the plant in its natural home, and take a solemn vow not to reveal its hidingplace to anyone.

Chapter III

Whilst there is no doubt that the homely names of many plants are the nicest, it is to be feared that quite often they are misleading. Of this there is perhaps no better instance than the case of the so-called “ club mosses," which, of course, are not true mosses at all. Indeed, in their general manner of growth these plants are quite closely allied to the fern tribe, albeit a number of the species bear a superficial resemblance to the mosses. It is interesting, in view of a certain amount of confusion, to indicate in a brief manner the habits of the typical club mosses, so that the observer will be able to decide in a few moments the nature of the plant which has come under his notice. However moss-like these plants may seem at the first glance, a small examination will reveal several distinctive features.