The first plant—Seaweeds in hot baths—Breaking of the meres—Gory Dew—Plants driven back to the water—Marsh plants—Fleur-de-lis—Reeds and rushes—Floating islands—Water-lilies—Victoria regia—Plants 180 feet deep—Life in a pond, as seen by an inhabitant—Fish-farming—The useful Diatom—Willows and Alders—Polluted streams—The Hornwort—The Florida Hyacinth—Reeds and Grass-reeds—The richest lands in the world—Papyrus of Egypt—Birds and hippopotami—Fever and ague.

WHAT was the first green plant? When was the surface of the earth first covered with flowers? Such questions are quite impossible to answer. We cannot even tell how plants ever came to exist on the earth at all. Wonderful as are the stories of the hardihood of bacteria, of spores, and of seeds, it is not possible to imagine that they could have been whirled or drifted through infinite space to this particular planet.

Yet it is at least probable that the first real plant on this world was a seaweed or alga.

In Germany and Austria there are certain springs in which the water coming from immense depths is at an exceedingly high temperature. These hot springs are used as natural hot baths, and have many interesting peculiarities. Amongst others there is the fact that certain seaweeds or algÆ are found luxuriating in the hot water. Some of these can even live in springs with a temperature of 176° F.! Such algÆ may have remained living in exceedingly hot water ever since that long distant time, the very first of all the geological periods, when there was no distinct separation betwixt land and water, and when the waters which were below the firmament had not been separated from those which were above it. Then the world seems to have been all fog and mist at a very high temperature.

But all theories on the origin of the world might be briefly summarized by the last nine words!

At any rate, the first plant was almost certainly a seaweed or alga not unlike those which produce the so-called "breaking of the meres."

At some seasons the water of certain lakes, usually quite clear and pure, becomes discoloured, turbid, and everywhere crowded with multitudes of tiny, bright, verdigris-green specks. The fish at once begin to sulk, refuse to take the fly, and live torpid at the bottom of the water. The minute green particles consist of a certain seaweed or alga. Mr. Phillips put the head of a common pin in the water so as to obtain a very small drop. When placed under a microscope, this minute amount of water was found to contain 300 individual algÆ.[102] This was in Newton Mere (Shropshire), and as this lake extends over 115 acres, it is possible to imagine the millions upon millions of algÆ which must have existed in it. The names of these seaweeds are many thousand times longer than the algÆ themselves, and it is not really necessary to give them. One of them, however, Aphanizomenon flos-aquÆ, has been noticed "tingeing with its delicate green hue the margin of the smallest of the Lochs Maben, in Dumfriesshire."[103] Yet it is not so big as the dot on the i in its name. Many other cases have been recorded of lakes that were coloured sometimes a "pea-green," or even brown or red by similar tiny little seaweeds. As we shall see, the water of such lakes generally contains a very large amount of suspended or floating vegetable life.

Another curious appearance is Gory Dew. Patches of a deep blood-red or purple colour are found on the ground or on walls. They have just the appearance of recently-shed blood. This also is due to an alga (Porphyridium cruentum). Dr. Cooke quotes from Drayton as follows: "In the plain, near Hastings, where the Norman William, after his victory found King Harold slain, he built Battle Abbey, which at last, as divers other monasteries, grew to a town enough populous. Thereabout is a place which, after rain, always looks red, which some have attributed to a very bloody sweat of the earth, as crying to Heaven for vengeance of so great a slaughter."

The ordinary "Rain of Blood" which appears on not too fresh meat, and looks like minute specks of red-currant jelly, is due to one of the Bacteria (Micrococcus prodigiosus).

The original algÆ or seaweeds probably had descendants which migrated to the land and eventually after many geological periods became our flowering plants and ferns. But the earth has become so richly supplied with plants of all sorts and kinds that it is now by no means easy for any plant to find a roothold for its existence. So that a considerable number have been forced back to the water, and have accustomed themselves to live in or even under water in company with their lowly cousins, the seaweeds, who remained below its surface.

These water plants are very interesting. They are always competing with one another. There is a perpetual struggle going on round every pond and loch, and by every river side.

If you look carefully round the edge of a loch or pond which lies in a grass field, certain series of plants are generally found to follow one another in quite a definite way. The first sign of water in grass is generally the presence of moss or "fog" between the grass-stems and the appearance of what farmers call the "Blue Carnation Grass." It is not a grass but a sedge (Carex glauca or C. panicea) with leaves rather like those of a carnation. A little nearer the border of the pond, there may be a tall coarse grass (Aira caespitosa or Festuca elatior). Next there is almost certain to be a fringe of Rushes. Where the Rushes begin to find the ground too wet for them, all sorts of marsh plants flourish, such as Water Plantain, Cuckoo-flower, the Spearwort Buttercup, Woundwort, and the like. As soon as the actual water begins, one finds, whilst it is still shallow, the Flag series of yellow or purple Irises, Bogbeans, Marsh Cinquefoil, Mare's Tail, and Sedges of various kinds. In this part the water ranges from an inch or two to about eighteen inches deep.

The Flag or Iris is a very common and yet interesting plant. It has a stout, fleshy stem lying flat on the mud, and anchored to it by hundreds of little roots. The flower is the original of the Fleur-de-lis, or Lily of France, which took the fancy of the King of France as he rode through the marshes towards Paris. (It is true that there are some unromantic authors who hold that the emblem was really intended to represent a frog or toad!)

The flower consists of three upright petals and three hollow sepals, which make so many canals leading down to the honey, and roofed over by an arched and coloured style. As the bee hurries down the canal to its nectar, its back is first brushed by a narrow lip-like stigma and then dusted with pollen. The leaves overlap in a curious way, and, when they have withered, their stringy remains serve to protect the fleshy stem. Orris root, which is used in perfumery, is the stem of the Iris florentina.

Most of the other plants in this Flag series will be found to have prostrate main stems growing under the water, but giving off flowering and foliage stems which stand up above it, so that the leaves and flowers are above the surface.

In the next part of the pond, where the water is from eighteen inches to nine feet deep, masses of reeds will be found usually swaying, sighing, and whispering in the wind. There are many kinds, such as Bulrushes, Phragmites, Horsetail, Scirpus, etc. It seems to be the depth, the exposure to wind, the character of the soil, and other unknown factors, that determine which of those will be present. All of them are tall, standing well above the water; their main stem is usually flat on the bottom of the pond, or floating horizontally in the water, but giving off many upright branches.

Floating islands are often formed by some of these horizontal main stems breaking off and being carried away. Those Chinese who possess no land make floating islands of such reeds for themselves, and grow crops on them. There are hundreds of such islands in the Canton River.

Beyond the reeds, one sees the large flat, floating leaves and beautiful cup-like white or yellow flowers of the Water-lilies. They grow in water which is not more than fifteen feet deep. Their long stalks and leaf-stalks are flexible and yield readily, so as to keep the flowers and leaves floating. There are narrow submerged leaves as well. The actual stem of the White Water-lily is about three inches in diameter, and stout and fleshy. It is full of starchy material, and lies upon the mud deep down at the bottom of the pond. There are many advantages in the position of the flowers, for bees, flies, and other useful insects can reach them easily, but slugs, snails, and other enemies cannot do so. The little seeds have a curious lifebelt-like cup, which enables them to float on the surface.

Of course, our own British water-lilies cannot compare with the magnificent Victoria regia of the tropics. Its petals are white or pink on the inside, and its gigantic leaves, six feet or more in diameter, can support a retriever dog or a child. There used to be some of them at Kew Gardens. A curious point about these enormous floating leaves is that they are covered with little spiny points on the under side and at the margin; that is probably to keep some sort of fish from nibbling at the edges.

But to return to our pond. Beyond the water-lily region and so long as the water is from twelve to twenty-four feet deep, Pondweeds are able to grow, and their leaves may be seen in the water, whilst their stalks stand up above the surface so as to allow wind to scatter the pollen.

This depth of twenty-four feet seems at first sight very great, but it is a mere nothing compared with the regions entirely below the water, where certain Stoneworts (Chara) and Mosses have been found flourishing. The former has been dredged up from depths of ninety feet, and a little moss was discovered in the Lake of Geneva growing quite comfortably at a depth of 180 feet below the surface.

But it is quite impossible to appreciate the wonder and beauty of the life in a pond unless by a strong effort of the imagination. Suppose yourself to be a fish two or three inches long, and accustomed to the dim, mysterious light which filters down through the water from the sky above. Every here and there great olive-brown leaf-stalks and stems cross and, branching, intercept the light. Everything, the surface of the mud, the stems and branches of the submerged water-plants, is covered by an exquisite golden-brown powder, which consists of hundreds and thousands of "Diatoms." Here and there from the Pondweed and other stems hang festoons or wreaths or threads of beautiful green AlgÆ. Little branching sprays of them, or perhaps of the brown kind, are attached here and there to the thick stems.

Even the very water is full of small, floating, vivid green stars or crescents or three-cornered pieces which are free floating AlgÆ or Desmids. Other diatoms are also free or swim with a cork-screwing motion through the water. Great snails and slugs crawl upon the plants, and weird large-eyed creatures, with a superfluity of legs and an entire absence of reserve as to what is going on inside their bodies, skirmish around. So that such a pond is full of vegetable activity. The free-swimming diatoms and desmids make up the food of the snails and crustaceans. These latter in turn are the food of fishes.

It is even possible to-day by carefully stocking an artificial pond with water plants, by then introducing Mollusca and Crustacea, and finally by the introduction of "eyed ova" or fry of the trout, carp, or other fishes, to produce a regular population of fishes which can be made more or less profitable, and the process can be spoken of as "fish-farming." Unfortunately there are a great many gaps in our knowledge as to what fish actually feed on, and we know even less about what the Mollusca and Crustacea require. There is, however, a distinct annual harvest of these minute seaweeds, of which different sorts appear to develop one after the other, just as flowering plants do. The two months January and February, which are almost without flowers, are also those in which most of these minute vegetables take their repose in the form of cysts or spores.

But these diatoms are too important and too interesting to be dismissed in such a cursory manner. Each consists of a tiny speck of living matter with a drop or two of oil enclosed in a variously sculptured flinty shell. They have, in fact, been compared to little protected cruisers which pass to and fro in the water and multiply with the most extraordinary rapidity.

If you (1) use dynamite to blast a rock, (2) if you employ a microscope or telescope, (3) if you paint an oil picture, (4) if you make a sound-proof partition in a set of offices, the probability is that it has been necessary to use the substance diatomite in each case. This consists of the accumulated shells of myriads of diatoms.

Nor does that represent by any means the whole of the usefulness of these tiny seaweeds. The oil shales, such as occur in Linlithgowshire and elsewhere, are supposed to be the muddy, oily deposits of such ponds as we have endeavoured to describe. The oil found in the shales was probably worked up by these diatoms in long-past geological ages. It may be used to-day either (1) to drive motors, (2) to light lamps, (3) to burn as so-called "wax" candles, (4) to eat (as an inferior sort of chocolate cream).

Interesting as these diatoms are, it is not really possible to understand their structure without the use of a microscope, so that we must pass on to another side of the activity of water plants. Let us, for instance, notice some of the ordinary plants to be found along a riverside. Willows and Alders are the ordinary trees, because they are specially fitted to stand the danger of being regularly overflowed. They easily take root, so that branches broken off and floated down are enabled to form new trees without much difficulty. In the United States, it has become a custom to plant Willows along the banks, because they are then not so liable to be broken down and worn away. Yet when a big Willow tree has become undermined, the weight of the trunk may cause it to fall over towards the water, so that a large section of the bank may be loosened and serious damage may be done if it is torn away by a heavy flood.

Amongst such Willows, should be mentioned the "cricket bat" kind, which has to be grown with the very greatest care, and of which a single tree may be worth £28.

Many of our rivers are, alas, sadly polluted by artificial and other impurities which kill the fishes and destroy the natural vegetation. When this happens a horrible-looking whitish fungus (Apodytes lactea) coats the stones and banks under water and the water swarms with bacteria. This fungus and the bacteria are really purifying the water, for they break up the decaying matter in it.

The oily or slimy character of the outside skin of all submerged plants is of very great importance to them. It allows the water to glide or slip over them without any friction.

Still keeping to our river bank, let us look for submerged plants. What is that dark green feathery plume? It is the Hornwort (Ceratophyllum) gently wriggling or moving from side to side. It has probably never been still for a moment since it first began to grow. Take it out of the water, and it collapses into a moist, unpleasant little body, but as soon as it is put in its natural element again it is seen to have a thin flexible stem along which there are circles of curved, finely divided leaves. Watch it in the water and one is filled with astonishment at the perfection of the shape, arrangement, and character of the leaves, which enables them to hold their place even when a flood may cover them with an extra twenty feet of water! The same sort of leaf, but with great difference in detail, is found in the submerged Water Crowfoot, Water Milfoil, Potamogetons, and others which live under the same conditions.

If it were the St. John's River, we might see that extraordinary Florida Hyacinth which has swollen, gouty-looking leaf-stalks, and grows with such extraordinary rapidity that it covers the whole surface of rivers, choking the paddle-wheels of steamers and destroying the trade in timber, for no logs can be floated down when it covers the water. Its rosettes float on the surface, and are very interesting to examine. If you upset one or turn it upside down in the water, the "buoys" or swollen stalks act as a self-righting arrangement, and it slowly returns to its proper position.

But in most rivers, one is certain to come across backwaters where it is impossible to force a boat through on account of the reeds and other marsh-plants.

There are places on the Danube where hundreds of square miles are occupied by waving masses of the feathery-plumed Phragmites, almost to the exclusion of any other sort of vegetation. Giant specimens of it eighteen feet high have been observed.

The same reed occurs in North and South America and far up towards the Arctic regions. At first sight it seems as if this was a mistake of Nature; why should so much of the surface be occupied by this useless vegetable? But it is necessary to say a little more about its habits and its object in life.

The most interesting and curious point is the way in which it grows in dense thickets; the main stem is really horizontal and below the water, but it gives off a number of upright stalks. Now every flood will carry in amongst the stalks quantities of silt and rubbish. Those upright stems will sift the water: all sorts of floating material, sand, silt, dead leaves, fruit, etc., are left amongst them. So that such a marsh or bed of Phragmites is gradually, flood by flood, collecting the deposits of mud, and the bed becomes every year more shallow. At the edge of the marsh there is scarcely any water visible, and grasses and other plants are beginning to grow between the Phragmites stems. Eventually these latter are choked out, and a marshy alluvial flat occupies the site of the old reed-bed.

So that the work of Phragmites is of the greatest possible importance: it has to form those fertile alluvial flats which are found along the course of every great river, and which are by far the most valuable lands in the whole world.

Look, for instance, at the population of Belgium, Holland, and Lower Germany, and notice how dense it is upon the alluvial flats where the Meuse, Rhine, and other rivers approach the sea. It is just the same in Britain. London lies on the great alluvial flats of the Thames, Glasgow on the Clyde, Liverpool on the Mersey. In China it is the Yang-tze-kiang valley (especially near its mouth); in India, the Ganges, of lower Bengal, and in the Argentine the La Plata River, which show the greatest accumulations of humanity. In every case it is the rich flat alluvium, which is exceedingly fertile when drained and cultivated, that has originally attracted so many people. Lower Egypt is the gift of the Nile, but it is not so much the Nile as these neglected water plants which made the rich lucerne, cotton, and food crops of Lower Egypt possible. Amongst the Egyptian Reeds one especially is of great importance. The Papyrus antiquorum, ten feet high, has much the same habit as our Phragmites and other water plants. It forms dense, almost impassable thickets, sometimes completely occupying and choking a small valley, or leaving only a passage, often changing and half choked, through a larger one. This, with other plants, makes the "sudd" of the Nile, which is one enormous accumulation of marsh plants and reeds floating on the water and covering a length of over 500 miles.

It was from the Papyrus that the ancient Egyptians made their paper. The stems are six to seven inches in diameter. "The pith of the larger flowering stems ... cut into thin strips, united together by narrowly overlapping margins, and then crossed under pressure by a similar arrangement of strips at right angles, constitutes the Papyrus of antiquity."

These great marshes and reed-beds are full of interest to naturalists. The Fens of Lincolnshire and the Norfolk Broads show the way in which water plants keep hold of the worn and travelled rubbish of the hills, and prevent most of it from becoming useless, barren sea-sands. These places, however, like the sudd of the Nile, and the Roman "Campagna," have an evil reputation so far as climate is concerned. This used to be the case even in lower Chelsea, in London (where snipe were shot not so very long ago). It is as if Nature had desired to do her own work in peace and without being disturbed, for fever, ague, mosquitoes, and malaria are very common. Yet a certain number of people always live in such places. In France, e.g., the leeches in the great marshes near the Landes form a source of riches. Such reeds also are or were the home of the hippopotamus, crocodile, and other extraordinary animals. The extinct British hippopotamus no doubt found in the Chelsea or other marshes a home as congenial to its tastes as is the sudd of Egypt to its living descendants or allies. In other places the enormous quantities of water birds, myriads of ducks, geese, swans, regiments of flamingoes, snipe, and the like, have called into existence peculiar kinds of industry in fowling and netting that are not without importance. The decoys in the Fens yield hundreds of birds for the London market, and the duck-punts with their huge guns also bring in quantities of wild fowl.

But all this industry is very trifling compared with that of Phragmites and its associates, who have strained from the water of the Thames most of the ground on which London now stands.