SEAWEED
When descends on the Atlantic
The gigantic
Storm-wind of the equinox,
Landward in his wrath he scourges
The toiling surges,
Laden with seaweed from the rocks;
From Bermuda's reefs; from edges
Of sunken ledges
In some far-off, bright Azore;
From Bahama and the dashing,
Silver-flashing
Surges of San Salvador;
· · · · · ·
Ever drifting, drifting, drifting
On the shifting
Currents of the restless main;
Till in sheltered coves, and reaches
Of sandy beaches,
All have found repose again.
Longfellow.
The minute algæ, which form patches of purple color on rocks, slimy layers or spots on wharves, bluish-green slime on mud, emerald-green films on decaying algæ, blue-green slime on brackish ditches, and so on, are various species of the subclass Cyanophyceæ. The prevailing color of these plants is blue-green, but some are purple, brown, or pink. Some of them are gelatinous in texture and shapeless, others have more definite forms; but all are too small to classify without the aid of a powerful glass, and are not of special interest except to the botanist.
Genera Oscillaria and Spirulina
The genus Oscillaria is so named from an oscillating movement which these filamentous plants show when viewed under the microscope. They are very delicate blue-green threads occurring singly, or in loose or felt-like floating masses, or like slime or scum, on mud or woodwork. In Spirulina the filaments are spirally twisted like a corkscrew and also have a vibrating movement. Spirulina is often found growing with Oscillaria, and forms purple patches on wharves.
Genus Calothrix ("Beautiful hair")
Filaments one tenth of an inch long, terminating in transparent hair-like points, occasionally branching. The plant grows in fine tufts or like a fringe on algæ or in patches on rocks. Sometimes it forms a spongy layer, again a velvety stratum. The color varies in different species; it may be bright green, brownish-green, [pg050] or dark bluish-purple. The genus is very common, and the plants are often found on the bottoms of boats.
Genus Lyngbya (Named for Hans Christian Lyngbye, a Danish botanist)
L. majuscula, mermaid's-hair. The filaments are curled or crisped, long, thick, and tenacious, matted together at the base, and blackish-green. The species grows in tufts on eel-grass and algæ, and is often found floating free. It is common in summer everywhere south of Cape Cod and on the Pacific coast.
L. ferruginea or æstuarii. In this species the filaments are thin, soft, and without stability (flaccid), so that they lie flat like a thin stratum. They are verdigris-green in color, and are found in brackish pools and ditches and on muddy shores near the sea. [pg051]
"There can hardly be a more fascinating group of plants than this, whether to the strictly scientific botanist or to the more catholic lover of nature. The green algæ are among the most widely diffused of plant forms. They grow practically in every place where enough moisture, together with light and air, is to be had. Between tide-marks on almost every coast, floating on the surface of the deep sea, covering damp earth, walls, palings, and tree-trunks, sticking to the surface of leaves in the moist atmosphere of tropical forests and jungles, and inhabiting almost every river, brook, pond, ditch, or casual pool of rain-water in all quarters of the globe, are members of this ubiquitous group to be found."[3]
The grass-green seaweeds are more simple in structure, and therefore are lower in order, than the red or brown algæ. They are among the lowest of all plants, many of them being minute single cells. They abound in fresh as well as in salt water, and in this respect differ from the other groups, the red and the brown algæ being almost exclusively marine plants.
As one approaches the shore, the attention is often attracted by the green mantle which covers everything overflowed by the tides. This consists largely of the confervoid algæ, which are very abundant and are found almost everywhere. They are dense tufts of fine thread-like plants, often matted at the base; sometimes they are sponge-like, floating masses.
The Ulvaceæ, the plants next higher in order, are the first which assume ribbon- and leaf-like expansions, and usually first engage the attention of the collector. [pg053]
In the green algæ are found the extreme forms of one-celled plants. In Pleurococcus the cell is microscopic in size. In the Siphoneæ the plant still consists of a single cell, but it attains large dimensions and develops into forms resembling, in outward appearance, leaf, stem, and root (see Caulerpa).
Other plants consist of single rows of cells, called filaments (Confervaceæ), or of cells arranged in layers or flat surfaces, called membranes (Ulvaceæ).
The silkweeds. This order is characterized by cylindrical cells strung end to end, forming threads or filaments, branched and unbranched. The plants inhabit both fresh and salt water, and are very abundant and widely distributed. They grow in dense tufts, often matted at the base.
Genus Ulothrix
A yellow-green, unbranched, decumbent, soft, hair-like fleece on the surface of rocks, extending indefinitely. This genus differs from Chætomorpha in the character of its filaments, which are soft and gelatinous in Ulothrix, but bristle-like and wiry in Chætomorpha.
Genus Chætomorpha
The frond is filiform; the filaments are coarse, rigid, and unbranched. In some species the filaments grow straight and in tufts from a definite base; in others they are twisted together and are prostrate. Often they are found floating in masses. In C. tortuosa the filaments are as fine as human hair, but rigid, and so closely interwoven as to resemble a layer of wool on the rocks. The cell-divisions give a striped appearance to the filaments when dry.
C. melagonium. This species is dark green, with filaments erect, coarse as a double bristle, and wiry; five to twelve inches long. It is found in rock pools from Boston northward. It does not adhere to paper in drying, and loses its color if immersed in fresh water. (Plate III.)
C. ærea. Yellowish-green, with filaments erect and less rigid than [pg054] in C. melagonium, which it otherwise resembles; tufts three to twelve inches long; cell-divisions very marked. This species is found in rock pools from Cape Cod to New York Bay.
C. linum. Bright green; filaments coarse, rigid, twisted together, and prostrate. It is found floating in masses and forming strata on rocks and gravel from New York northward. It is thought by some that this, as well as C. picquotiana, which it closely resembles, is not a true species, but consists of the mature plants of the species C. melagonium and C. ærea, which have become detached from their holdfasts and have continued to grow. (Plate III.)
Genus Cladophora ("Branch-bearing")
Frond filiform, branched. There are many species of Cladophora, which differ from one another in their branching, color, and size. They abound on rocks at low-water mark, in tide-pools, in muddy ditches, and on wharves. They are especially characterized by being so profusely branched as to form tufts or spherical masses, by which the collector can easily distinguish the genus.
C. arcta. Bright, glossy green; filaments fine, erect, much branched, two to eight inches long; tufts dense, more or less entangled, and in bunches, giving a starry effect. The species is common on rocks near low-water mark from New York northward. The plants vary slightly in appearance with the season. (Plate III.)
C. rupestris. Dark green; filaments straight, rigid, tufted; branches crowded; many branchlets flattened against the filaments, so that the alga somewhat resembles grass; five to ten inches long. The cell-divisions show plainly. Plants of this species do not adhere to paper in drying. They are found on rocks at low-water mark, and are common on the northern New England coast. (Plate III.)
C. gracilis. Bright yellow-green; filaments very fine, loosely tufted, three to twelve inches long, soft, silky, much branched; branches rather short, and branchlets more or less curved and arranged in a comb-like manner. It grows on wharves, in muddy pools, and on eel-grass. (Plate IV.)
The plants of this order are, with few exceptions, formed of celled surfaces and show the earliest type of an expanded leaf. The cells form thin membranes, which sometimes are broad surfaces of no definite shape, sometimes are narrow and ribbon-like, or they may be simple or branched tubes. When the membrane [pg055] consists of a single layer of cells it is Monostroma ("one layer"); when it consists of a double layer it is Ulva; when the layers separate, the thallus becomes hollow, and it is then Enteromorpha. These plants are mostly a brilliant grass-green in color, are silky in texture, and are attached by a small disk to rocks and stones. They abound everywhere, and are commonly known as green laver.
Genus Ulva
Frond a thin, silky, flat membrane, sometimes leaf-like, again an extended surface of no definite shape. These are the largest green algæ. They are common everywhere.
U. lactuca, the sea-lettuce. Frond a flat membrane of various shapes, sometimes orbicular, again deeply incised, often ribbon-like; margin always much waved or ruffled. In the variety rigida the frond is oval in outline, not very large, and quite firm or rigid. The species is found on rocks exposed to the action of the waves. (Plate IV.)
U. latissima. Frond a flat, expanded membrane of indefinite shape, but general outline oval, never ribbon-like; attains a size of twelve to twenty-four inches; often deeply lobed, very waved, often perforated with holes; membrane brilliant green, thin, smooth, glossy. It grows apart or in tufts, and is found everywhere, in all stages of growth. It is the largest species of Ulva, and is very common on muddy shores.
Genus Enteromorpha
Fronds tubular, simple or branched, sometimes inflated. The tubes vary in size in different species and also in the same species, some being fine like a hair, others large, and flat or inflated. The genus is widely distributed and very abundant. Species of Enteromorpha grow on the bottoms of ships, and in nautical language are called grass.
E. clathrata. Fronds thread-like, tubular, branched, and branches beset with numerous fine branchlets; densely tufted, soft. Common everywhere. (Plate IV.)
E. compressa. Fronds long, slender, branched, tufted; branches simple, compressed, extending from main central branch, obtuse at ends, but attenuated at base. The species is very abundant everywhere, and is a useful plant for the aquarium. (Plate V.)
E. intestinalis. Single, long, inflated tubes or sacs, obtuse at the apex, very attenuated at the base; fronds often crimped and twisted, resembling an intestine, whence the name. (Plate V.) [pg056]
E. lanceolata. Formerly called Ulva Linza. Frond narrow, ribbon-like, six to twelve inches long, one inch to two inches wide; blunt or pointed at apex, tapering at base; attached by a disk; edges much ruffled; bright green, soft, thin.
Genus Monostroma
This genus resembles Ulva, but is more delicate since it has but one layer of cells, as its name implies. The frond is usually sac-like at first, then breaks apart, leaving a thin, semi-transparent membrane of no definite shape.
The distinct and peculiar character of this group is that in each individual the whole plant consists of but one cell. There are many genera, some of which are plants of elaborate form and considerable size, but always the one cell expands and branches without dividing the elongated cavity with septa, or plates of division. In Caulerpa the stability of the plant is secured by numerous fibrils which emanate from the interior of the cell, forming a spongy network of interlacing filaments. In other orders the branches gain support from incrustation, from interlacing, and from cohering on the edges.
The algæ of this order are found only in tropical or subtropical waters. Their holdfasts resemble fibrous roots and penetrate the sand or coral on which they grow.
Genus Chamædoris
C. annulata. When young this alga consists of an annulated tube formed of a single cell. The annular constrictions occur at short intervals, giving it the appearance of being jointed. It grows to the height of two to three inches, when it ceases to lengthen and produces a dense mass of filaments, forming a head or spherical tuft one inch or more in diameter. It is bright grass-green in color, rather rigid and tough, and when mature is thinly coated with carbonate of lime. The holdfast is a tuft of fibers. The species is found at Key West and is a native of the West Indies.
| PLATE V. | |
|---|---|
| Enteromorpha compressa. | Enteromorpha intestinalis. |
| Enteromorpha intestinalis. | Anadyomene flabellata. |
| PLATE VI. | |
|---|---|
| Acetabularia crenulata. | Dasycladus occidentalis. |
| Penicillus dumentosus. | Udotea conglutinata. |
A. flabellata. Frond composed entirely of branching filaments, which unite and form an undulating, rigid membranaceous surface, which seems like a network of veins. The species grows in bunches on short stems in the fissures of tidal rocks, and at first view resembles young Ulva. It is a very curious and beautiful alga, and should be examined with a glass. It is one inch to four inches in diameter when full-grown. (Plate V.)
This order also inhabits only tropical or subtropical seas. It is placed in this group, although only the main axis is unicellular. The one-celled axis is surmounted or encircled by whorls of minute filaments or branchlets (ramuli), which protrude through small holes and are either persistent or deciduous. In the latter case the fallen filaments leave disk-like scars on the stem.
Genus Acetabularia
A. crenulata. This little alga resembles a mushroom of the Agaricus variety or gilled species, and so is easily identified. It is thinly incrusted with lime and is found on rocks and coral, within tide-marks, on the Florida reefs. When full-grown the stipe is two to three inches long and the cap one half of an inch in diameter. (Plate VI.)
Genus Dasycladus
Fronds destitute of calcareous matter, soft, cylindrical or club-shaped; single unicellular axis, beset with fine filaments or ramuli.
D. occidentalis. Frond club-shaped, one to two inches high, one half of an inch or less in diameter; covered with whorls of fine filaments, making the fronds almost spongy; substance soft but tough; dark green. These plants have been compared to foxes' tails. They grow in bunches on rocks between tide-marks. (Plate VI.)
Genus Cymopolia
C. barbata. Frond branched, dividing regularly in pairs; thickly incrusted with lime. Annular constrictions at short intervals give the branches the appearance of strings of beads. Each section is covered with pores or scars of fallen ramuli. The branches terminate in tufts of fine filaments. [pg058]
Genus Penicillus
The merman's shaving-brush, characteristic of coral reefs.
P. dumentosus. Holdfast much branched, like a fibrous root, and penetrating deep into the coral or sand; stem short, thick, more or less flattened, sometimes hollow, covered with velvety scurf; top covered with loosely spreading tuft of soft filaments three to six inches long, which branch repeatedly in pairs (dichotomous); color deep green. When old, these plants are incrusted with a thin, porous layer of carbonate of lime. (Plate VI.)
P. capitatus. Holdfast a dense mass of fibers two or more inches long; stipe one to five inches long, one fourth to one third of an inch in diameter, usually cylindrical, sometimes wider at top than at base, sometimes flattened; thickly incrusted with lime, which is smooth and often polished; top a dense, spherical mass of filaments one to two inches in diameter; filaments branching dichotomously, and rigid from incrustation of lime.
P. Phœnix. Stipe cylindrical, one to three inches long, one fourth of an inch in diameter, thickly incrusted with lime, smooth; capitulum or head ovoid, and composed of filaments which are incrusted with lime and coherent, forming many distinct, flat, wedge-shaped, level-topped, spreading laminæ. This species is found at Key West.
Genus Udotea
U. flabellata. Short, flattened stem, expanding into a broad, fan-shaped, smooth frond, concentrically zoned; margin wavy; thickly incrusted with lime. Abundant at Key West.
U. conglutinata. Deeply descending root; stem expanding into fan-shaped frond; entire, lobed, or irregularly torn; slightly incrusted with lime. The frond is composed of longitudinally parallel, adherent filaments, which are visible, giving a striated, rough surface. (Plate VI.)
Genus Halimeda
This genus resembles the corallines externally, and is abundant on coral reefs. It appears as if formed of separate parts, resembling a series of heart- or kidney-shaped segments strung together. The plants are more or less incrusted with lime. The branching holdfast grasps particles of sand, and with them forms a solid ball.
H. tuna. Articulations roundish or half kidney-shaped, one half to three quarters of an inch broad; frond flat, smooth, and thinner than most species; bright green; somewhat flexible. (Plate VII.)
H. tridens. Fronds solitary, erect; base composed of confluent articulations; above divided into numerous branches of articulations, which are all flat, and in one plane giving a fan-shaped outline; middle joints wedge-shaped; upper ones divided into three lobes, frequently bearing articulations at the summit of each lobe; thinly incrusted with lime; color bright green. (Plate VII.)
H. opuntia. Articulations kidney-shaped, flat, rather thin; margins scalloped; irregularly branched and spreading; dense tufts.
Genus Bryopsis
("Moss-like")
There are said to be about twenty species of this genus. They are distinguished by the manner of branching, but are not very definitely marked. All are erect, one-celled, branching stalks, and are feather-like in appearance.
B. plumosa. Fronds branched twice or more; branchlets or pinnules tapering as they rise on the stalk, giving a triangular outline; stalk naked below; plants a vivid dark green in color, two to six inches long, growing in tufts on wharves and stones at low-water mark and in tide-pools. It is common along the whole Atlantic and Pacific coasts. It is well to use salt water for mounting this alga, since the green coloring-matter or granular endochrome with which it is filled easily escapes. (Plate VII.)
Genus Codium
C. tomentosum. This is called the commonest seaweed in the world. It is abundant in every latitude, yet it does not appear on the eastern coast of North America. It is found on the gulf coast of Florida and is plentiful on the Pacific coast. The fronds are often a foot long, composed of closely packed, club-shaped branches dividing in a forking manner, and densely covered with fine filaments which give them a soft, sponge-like texture. (Plate VII.)
Genus Caulerpa (From two Greek words meaning "stem" and "creep")
Caulerpa is the only genus of its order, but it contains about a hundred species, many of which resemble mosses, ferns, or cacti. Each plant is composed of a single cell, however much it may be [pg060] ramified. The frond consists of a prostrate stem, from the lower side of which root-like fibers or holdfasts descend into the hard sand or coral, and from the upper side leaf- and branch-like secondary fronds arise. These plants grow luxuriantly in tropical waters, extending over large surfaces, and are the chief food of turtles. (Plate VIII.)
C. prolifera. Frond or lamina flat and leaf-like, two to four inches long, one half to three quarters of an inch wide, either simple or once forked; margin entire. Similar laminæ spring from the surface or from the edge or base of the different leaf-like portions. Laminæ rise from the upper side of the creeping, rooting stem. Its substance is somewhat horny and translucent.
C. Mexicana. Prostrate, creeping stem, with rootlets or holdfasts below, and leaf-like fronds above; fronds simple or with one or two branches deeply cut in narrow lobes nearly to the center. The species abounds at Key West. (Plate VIII.)
This subclass contains some of the most remarkable of the seaweeds. It is especially notable for the diversity of its plant forms, which range from filaments to plants which appear to have stems and leaves (Sargassum). The species vary in size from very small fronds to those of immense size (the Laminariaceæ). It includes Fucus (the rockweeds), a very conspicuous genus, which furnishes fully three fourths of the vegetable covering of the tidal rocks in the localities in which it grows.
This order comprises many species of branched, filamentous plants, some of which are of hair-like fineness and form beautiful feathery tufts of brownish or olive-green color. They resemble, except in their tawny color, the green alga Cladophora.
The name is derived from Greek words meaning "outside" and "fruit," the spores of the plants being borne on the branches.
The species are determined by the arrangement of the spores, according as they are in the pod-like branches, in groups, or in cases on stalks. Since these differences are not perceptible to the naked eye, it is impracticable to describe many species, or for the amateur collector to try to separate them.
Genus Ectocarpus
E. littoralis. Filaments fine, in dense tufts, interwoven, six to twelve inches long; pod linear in the substance of the branches; color olive-green. This is the most common species of Ectocarpus, and grows abundantly everywhere, appearing like large, fine, dull-green plumes. (Plate IX.) [pg065]
E. siliculosus. Tufts loosely entangled at the base, free and feathery above, of indefinite length; spores in pod-like forms at the ends of the branches. Common on the larger algæ and on wharves.
E. viridis. Tufts a little more loose and expanding than in E. siliculosus; spores in pods at the base of the branches. (Plate IX.)
E. tomentosus. Fine filaments, densely interwoven into rope-like, spongy masses, two to four inches long; yellowish-brown; pods on stalks. Found in summer growing on Fucus.
Genus Sphacelaria
S. cirrhosa. Olive-brown; branched, feathery filaments, one half of an inch to two inches long. Each branch ends with an oblong, swollen cell containing a dark granular mass which gives it a withered appearance. These cells can be seen with a strong pocket-lens. It forms dense, globe-like tufts on Fucus.
S. radicans. Filaments one half of an inch to one inch high; branches few and hairy. It forms a dense, grass-like covering, of indefinite extent, on the under side of muddy rocks. Found on the New England coast.
Genus Cladostephus
C. verticillatus. Fronds bristle-like, dividing regularly; covered with whorls of branchlets set close to the stems, each whorl overlapping the previous one, giving the plant a spongy appearance. (Plate IX.)
Genus Ralfsia
The species of this genus are brown, leathery, crustaceous expansions of indefinite form, one inch to six inches in diameter, resembling lichens. They appear on rocks in shallow, exposed pools.
Genus Punctaria
Dotted-weeds. Fronds pale olive-green, membranaceous, leaf-like, with short stem; covered with spores which appear like dots.
P. latifolia. Frond pale green, four to twelve inches long, one inch to five inches wide, leaf-like, and tapering suddenly to a short stalk; much [pg066] waved on margin; substance soft and thin; dotted with spores. In the young plants fine hairs emerge from the dots, but disappear later, and the fronds become darker and more rigid. Found in summer on rocks and on other algæ on the Long Island and New England coasts.
P. tenuissima. Fronds smaller and more slender than in P. latifolia; thin and delicate. Found on eel-grass and Chorda filum.
P. plantaginea. Fronds dark brown, leathery, leaf-like, blunt or wedge-shaped on top; dense clusters of hairs on the dots; six to twelve inches long, one inch to one and a half inches wide.
Genus Asperococcus
This genus differs from Punctaria in having a tubular instead of a flat frond. (Plate IX.)