By the deep sea

The most striking seaweeds owing to their size and abundance are those comprised in the Fucaceæ, all the species of which are olive-brown in colour. There are four species of Fucus which are very abundant on our shores, as well as representatives of other genera included in the family. On the highest of the rocks, that only become covered by high spring-tides, and are only washed by rough seas, there grows in abundance a little leathery plant called the Channelled Wrack (Fucus canaliculatus). During the greater part of its existence it is dry and shrivelled and of black hue, but when covered by the tide it absorbs the water, and becomes soft, with an olive-brown tint. The frond is much branched, the segments long and narrow, the edges being turned in so that on one side they appear to be deeply channelled. It is the smallest of our species of Fucus, and is readily distinguished from its congeners, not only by its size, but by the channel-like folding, the absence of air bladders, and the lack of a mid-rib. At the extremity of some of its fronds there are irregular warty pod-like organs of a dark orange tint. These are known as the receptacles, and they contain the elements necessary for the production of spores, whereby the plant is reproduced. In one plant these elements will be all male (antherids), in another all female (oogones). If you will examine one of these club-shaped orange organs with your pocket lens, you will observe that its surface is pitted with a considerable number of round pores, and if you cut across the whole body just on the edge of one of these pores, you will find it communicates with a globular cell in the substance of the receptacle. These cells are known as conceptacles, and their number corresponds to that of the pores. Their walls are clothed with a felt-work of threads, upon which are borne, in the male conceptacles, minute egg-shaped cells (antherids), which ultimately burst, and set free thirty-two or sixty-four tadpole-like bodies (antherozoids), each with two tail-like threads (cilia) attached to the under part. By the lashing of these organs they make their way out through the pore of the receptacle into the sea.

With the development of the antherozoids, a similar activity has taken place in the female conceptacles, where bodies approaching more to an ellipsoidal or spherical form (oogones) have appeared, and their contents have broken up into two, four, or eight smaller bodies (the oospheres). On their escape into the water, they are each surrounded by a number of the antherozoids, which pierce the substance of the oosphere, become absorbed in it, and so fertilise it. Development then commences in the oosphere, and it gives rise to a new Fucus plant. This form of reproduction is by no means common to the whole class of seaweeds; on the contrary, there are many important variations of it, which for want of space we shall be unable to refer to in detail. This is the highest type of reproduction in the Algæ.

The Channelled Wrack never exceeds a few inches in length, but another species, which agrees with it to the extent of possessing no mid-rib, varies from two to six feet. This is the Knotted Wrack (Fucus nodosus), which may be at once identified by the possession of solitary bladders in the centre of its rib-less frond, and producing a very gouty appearance at intervals. These are air-cells, sometimes measuring two inches, which give buoyancy to the plant. Above the bladders the frond divides, and from these branches (but not at their extremities, as in the Channelled Wrack) the pear-shaped reproductive organs are produced.

Another Wrack that possesses these vesicles, is the so-called Bladder Wrack or Black Tang (Fucus vesiculosus), though there is little danger of confusing the two species. The Bladder Wrack has a much broader, flatter frond than the Knotted Wrack, and a very distinct mid-rib. The bladders, too, are smaller, and instead of being solitary, are arranged in groups on each side of the mid-rib. The plant is about two feet in length, and exceedingly plentiful.

Very similar, and equally plentiful, is the Saw-edged Wrack (Fucus serratus), with flat, branched fronds and mid-rib, the branches much broader than in Bladder Wrack, and the edges cut into bold, sharp, distant teeth. Its usual length is from two to three feet, but it may occur as long as five or six feet. The width of frond also varies, for it may be anything between half an inch and two inches. Where the frond branches the mid-rib becomes thicker and bolder. It is quite innocent of bladders. The name of the genus is founded upon the word Phukos, which is the Greek name for a seaweed.

Almost equally plentiful with those species of Fucus we have named, is the Pod-weed (Halidrys siliquosa), with long attenuated compressed fronds, four or five feet in length, much branched, most of the branches being exceeding short, but others ending in air vessels. These are ribbed transversely, and bear a very close likeness to the seed-pods of the furze. They run out to a narrow point at the free end, and are divided into small air-chambers within. But there are other pods that contain the reproductive elements, and these may be known by the pores by which their surfaces are perforated. The name Halidrys, signifies sea oak (Greek, Hals, the sea, and drus, oak), but the why and wherefore of the name are not easily determined. If the abundant pod-like vessels are kept in mind, there is no difficulty in knowing this species the first time it is seen.

At low-water, you will often find, attached to the rocks, a shallow horny cup, or button, of olive hue, about the size of a penny. This is the Sea-thongs (Himanthalia lorea), which gets its name from a very long, branched, strap-like growth from the centre of the cup. The cup is the frond—the plant proper—and the extraordinary straps, which may be half an inch wide and twenty feet long, are merely the receptacles containing the reproductive organs, which open by pores all over their surfaces. The receptacles are not produced until the second year of the plant’s life, so that many examples will be met consisting of the cup-like frond only. It is a local plant, and not therefore to be found on all parts of the coast.

In the lower series of tide-pools, a tufted weed attracts the sight by reason of its brilliant iridescence, which often causes it to be plucked from its native pool, only to be thrown back again, for on emergence from the water all the beautiful play of colour has gone. It does not appear to have any common name, but to give it a chance of being popularly known, let us call it the Rainbow Bladder-weed (Cystoseira ericoides). The many branches of its frond are full of little bladders, whence its scientific name (Kystos, a bladder; seira, a cord), and it gets its specific title of ericoides from its habit somewhat resembling that of the Heath-plant (Erica). A tuft pulled up and carefully overhauled will afford the zoologist a number of diverse forms of life. Several species of crustacea make it their home, and the leaf-worms hide themselves in the centre of the little bush. Mollusks, sponges, and ascidians are there also, and the description of the animal inhabitants of such a tuft would make a fair chapter.

All the species of seaweeds to which we have already referred, are members of the class Fucaceæ. We have now to take a glance at other brown and olive weeds, some of which are the giants of the tribe, but which belong properly to the deeper waters, though every gale will make us well acquainted with their forms heaped up upon the shore. In this class—known to botanists as the Phæosporeæ—the reproduction is generally of a lower type than in those we have been considering. In the majority of forms there is no sexual process, the species being reproduced, as a rule, by zoospores, which are somewhat similar to the antherozoids of Fucus. They are produced in special cells, the contents of which break up into a number of these zoospores, which escape through a pore, and germinate.

Getting down into a drang at extreme low spring-tide, we shall find the rocks to seaward covered with Tangle (Laminaria digitata), whose huge round stems clasp the rocks with their claw-like false roots. The leafy portion is broad, of a pale olive-brown, and slit up into several sections, so that the whole frond has a rough resemblance to the diverging fingers of a huge hand: hence its name, digitata (having fingers). The substance of the frond is thick and leathery. A species with undivided glossy narrower fronds, puckered and frilled, is the Sugar Tangle (Laminaria saccharina), so-called because, when drying, it produces on its surface a white powder of a sweet taste, called mannite, or manna. This substance can also be obtained from the cells by maceration. Subsequent evaporation of the brew results in a deposit of crystals. This is the species that inland trippers carry away on their visit to the coast to act as a hygrometer, hanging it on a nail, and feeling it from time to time to find if it is dry and hard, or moist and pliable, for its cells readily absorb moisture from the atmosphere, and as readily part with it when the air is again dry and clear.

A third species is called the Sea Furbelows (L. bulbosa), and it may often be found washed up in great heaps after a storm. It springs from a great hollow sphere, which is perforated, and thus affords a home for many creatures. This so-called bulb is sometimes a foot across, and from its stem there is a great expanse of thin leather split up into many broad ribbons. These three species, with the larger Fuci, are largely used by farmers near rocky coasts for manuring their fields, and in former days, more widely than now, they were employed in the manufacture of “kelp” and iodine. These Laminarians have the curious habit of casting off the lamina or blade of the frond each year, by a constriction above the stem, whence a new one grows. This, too, it should be stated, is the growing point, the blade increasing in length by additions near the stem, instead of by the lengthening of the free end. The spores are produced in large patches upon the surface of the frond.

The Badderlocks or Murlins (Alaria esculenta) of our northern coasts, belongs to this group, but is distinguished from the Laminaria by the possession of a mid-rib or central nerve. The stem is short and cylindrical, and the blade of the frond ranges from three to twenty feet in length, usually much torn by the waves. There are a number of finger-like receptacles given off by the stem, and in the outer coats of these are the conceptacles bearing the spores. The plant is used as food by the poorer classes resident on the shores where it is plentiful, and is eaten raw, when it is said to be the best of our esculent seaweeds; the parts preferred are the mid-rib and the receptacles. “Badderlocks” is a corruption of Balder’s locks, the split fronds being likened to the locks of the Scandinavian hero Balder, to whom all plants except mistletoe swore fealty.

To this class also belongs the slender and very extensive Sea Lace (Chorda filum), which consists of a rounded frond, hollow, and without branches. It is remarkable how tenacious the thong-like, slimy fronds are, and it is not difficult to imagine the difficulties of a swimmer who should have to force his way through a bed of them. The tubular interior is divided up into a number of cells by transverse partitions; and the spores are embedded in the outer surface. It prefers a sandy or muddy bottom in creeks and harbours, and in such places it grows in dense patches, the fronds attaining a length of from twenty to forty feet. The free end is constantly dying off, but the plant increases by growth at the lower end, just above the false roots.

The Fennel-leaved Netweed (Dictyosiphon fœniculaceus) is abundant in rock-pools all round our coast. As its name implies, the frond is much branched and thread-like. It is a light olive in colour, and grows in tufts on stones and larger weeds. The arrangement of the cells in the walls of the frond produce a net-like appearance.

Everyone knows the thin flat transparent fronds of Sea Lettuce (Ulva latissima), which grows everywhere on the coasts, its margins crisped, folded, torn, or otherwise diversified by Nature, or the many things that feed upon it. It is mentioned out of its place here, in order that we may bring into its proper order a plant that is frequently taken as a mere aberration of the Ulva. This weed is the Asperococcus turneri, a hollow green bladder on a short stalk, and rough with the spore-bearing organs. It is commonly found adhering to stones between tide-marks.

One of the most beautiful of our seaweeds is known as the Peacock’s Tail (Padina pavonia). It is really a tropical species, but its range of distribution extends to our most southern shores, and, strange to say, without suffering any deterioration in its brilliance of hue or its stature. From a very narrow base the frond gradually expands to a broad fan-shape, and the edges are curled in so that it assumes a cup-shape. But the chief beauty of the plant is given by a number of concentric lines and bands. Several of these bands are white, as though they had been chalked: their colour is in fact due to a chalky powder, calcium carbonate, which is secreted by the plant. Many of the lines are formed by a fringe of glistening hairs, which reflect the light and break it up into all the colours of the spectrum, and a more distinct fringe decorates the upper margin of the frond. Reproduction takes place by the formation of large spores, which are found in heaps between the zones. These are known as tetraspores, because the contents break up into four smaller spores. Sometimes this weed is what botanists term proliferous, that is, it produces new plants upon its frond. Like all those showing iridescence, it is a much more beautiful species in the water than in the herbarium; though it is not without beauty there, and it is a prize eagerly sought by collectors.

It is worthy of note that fresh-water Algæ are, with very few exceptions, green, whilst few of the marine species are truly green; brown and olive, and red, are the prevailing hues. The green marine weeds are nearly all found in shallow water. Of course, they all possess the green colouring matter called chlorophyll, but in the deep-water species, according to Murray and Bennett, “it appears to be essential ... that the green colour of the chlorophyll should be masked by a coloured pigment, red in the case of the Florideæ, brown in those of the Phæosporeæ and Fucaceæ.” It is from these latter classes our examples have been already drawn; we must now give a turn to the Florideæ, which contains many of the most popularly sought species, because they are often so charmingly tinted and so delicate in structure.

It must not be supposed from the foregoing remarks that the whole of this class are red weeds; the majority are not only red but brilliant red; whilst others are purple, brown, yellowish, or dirty-white. They are chiefly small weeds, but they make up for the want of stature in their delicacy of texture and fineness of division.

A very beautiful genus of delicate red and purple weeds, chiefly growing upon the larger and coarser kinds, is called Callithamnion (Greek, Kalli, beautiful, and thamnos, shrub). Some attain the length of half a foot, but most of them are much smaller. They require careful examination with lens or microscope to decide the species, and oftentimes in order to distinguish them from other finely branched red weeds. For their proper discrimination we advise reference to a book devoted exclusively to Seaweeds, such as Landsborough’s, Gray’s, or the splendid “Phycologia Britannica” of Harvey. The general characters of the genus are: frond branched, often pinnate, consisting of jointed threads, with tetraspores scattered along the branches.

Other small red seaweeds will be found, representing several genera, but they require the assistance of coloured figures to make descriptions interesting and useful. There is the silky Ptilota, with finely divided fronds, consisting of cells alternately filled with a pink and a transparent fluid; the rosy red Griffithsia, with thread-like fronds and clear transparent joints; the forking threads of Ceramium, their tips curled in towards each other; the exquisite Plocamium, with its flat crimson, hair-like branches, toothed on one side only.

The Coralline (Corallina officinalis) grows in every pool, and its stony-coated joints are well-known, though it is a shock to some persons to find it classed among plants, when they had long imagined it to be related to the corals of which necklaces and islands are constructed. There are, in fact, several genera whose members secrete carbonate of lime, and so hide their vegetable character. The coralline was, however, once soft and flexible. Melobesia is equally stony, but grows in thin horizontal pink and purple plates or solid masses. A little weak muriatic acid will soon dissolve the lime, and reveal its true character. Jania somewhat resembles Corallina, but its branches are exceedingly slender, and much shorter than Corallina.

Another edible weed is the well-known Irish Moss or Carrageen (Chondrus crispus), which was in such favour years ago as an invalid’s food. It is well shown in the illustration, but is subject to great variation, especially as regards colour, ranging from greenish-white, and yellow, to a dull purple. In some of its forms it closely resembles Gigartina mamillosa, to which it is not very distantly related, and the danger of confusing the two is increased by Gigartina often growing amongst Chondrus. The tips of Gigartina’s frond, however, are usually broader than those of Chondrus, and the frond is rough, with little tubercles like grape-stones (Greek, gigarton), which contain the spores. The usually purplish fronds will be found, on cutting them across, to be not solid, as they appear, but composed of delicate threads, in a firm clear jelly.

A pretty little red weed, that is abundant in the rock-pools, growing upon other weeds, is the Chylocladia parvula, which has swollen, cactus-like ovate joints, of a clear red, appearing as though they were skins filled with liquid. It is allied to Plocamium and Rhodymenia.

The most striking of all these red-spored algæ, at least, so far as the British flora is concerned, is the (for a seaweed) extraordinary Ash-leaved Seaweed (Wormskioldia sanguinea), whose frond has a distinct leaf-like form, with a mid-rib and branching nervures. Its texture is so very thin, that in spite of its beautiful rosy tint, if a specimen were laid upon this page, the print could be read through it. Its margins are more lax than the mid-rib, so that when mounted for the herbarium, the edges show many foldings over. The plant was formerly placed in the genus Delesseria, but is now separated on account of important differences in the matter of propagation. In this species minute leaf-like organs spring from the mid-rib, and may be taken for young plants springing from the parent, but these are really the bodies that bear the spores.

The Winged Delesseria (Delesseria alata) is a finely and intricately branched plant, of a rich dark crimson colour, with a suggestion of a mid-rib, along each side of which is a narrow expanse of thin membrane, the “wings” of its popular and technical names. It occurs in thick tufts on the stems of Laminaria digitata.

My space is getting rapidly used up, though I have only been able to mention a few of our fairly common seaweeds. There are still two or three that I must mention. One of these is an exceedingly pretty little form, which would be very like a soft feather that has been cast by one of the greener varieties of the canary-bird, if it were not so vividly green. The weed is called Bryopsis plumosa. It will be found growing on the shaded walls of deep pools, and if the eye is placed just over the edge of the pool, the Bryopsis will be found growing at right angles with the wall, and looking so very feathery that it will be identified at once.