Alaria esculenta is an edible species known as the Badderlocks in Scotland, and also locally as the Henware, Honeyware, and the Murlins. It has a fibrous root, and a stalked, lanceolate, entire frond with a distinct midrib throughout. The stem is winged with finger-like leaflets, in which the spores are arranged in oblong clusters.

In the genus Chorda the frond is a simple, cylindrical tube, divided internally by numerous transverse membranes, and the spores are distributed over the surface. The commonest species is C. filum (see Plate VIII.), the frond of which is very slimy, and often from ten to twenty feet in length. In its young state it is covered with gelatinous hairs, but these are worn off as the plant develops. A smaller species (C. lomentaria) is sometimes found on our shores. Its fronds are constricted at intervals, taper at the tip, and grow in tufts. It is seldom more than a foot long, and is not of a slimy nature.

The Sporochnaceæ have inarticulate, thread-like fronds, and the spores are contained in oblong, stalked receptacles, each of which is crowned with a tuft of slender jointed filaments. The typical genus contains only one British species—Sporochnus pedunculatus—and even that is by no means common. It is, however, a very pretty weed of a delicate texture and pale olive-green colour. Its stem is long and slender, pinnately branched, and the branches bear numerous small thread-like tufts.

The same order contains the genus Desmarestia, in which the frond is long and narrow, thread-like or flattened, with a tubular jointed thread running through it. Young specimens have marginal tufts of branching filaments. The species decay very rapidly after removal from the water, and should therefore be dried and mounted as quickly as possible. D. ligulata, so named from the flat, strap-like frond, is common on all our coasts. It is pinnately branched, and all the branches and branchlets taper towards both ends. D. viridis has a cylindrical, thread-like and freely-divided frond, with opposite branches and branchlets. It occurs more commonly on the northern shores.

The last order of olive-spored weeds is the Fucaceæ, some species of which are so abundant between the tide-marks, from high-water to low-water levels, that they form a very important characteristic of our shores. They are mostly large, tough, and leathery weeds, without joints, and the spores are contained in spherical receptacles embedded in the substance of the frond.

In the typical genus—Fucus—the root is a conical disc, and the frond flat or compressed and forked. Most of the species are furnished with one-celled air-vessels in the substance of the frond, and these serve to buoy up the plants and keep them more or less erect when submerged. The spore-receptacles are usually embedded near the tips of the branches, but are sometimes borne on special branches or shoots. They are filled with a slimy mucus and contain a network of jointed filaments. The weeds are very hardy, capable of withstanding long exposures to air and sun, and are sometimes to be found above high-water mark, where they are watered only by the spray of the waves for a brief period at intervals of about twelve hours. Although they are not usually looked upon as ornaments in the collector’s herbarium, they will repay examination for the tufts of smaller and more beautiful weeds to which they often give attachment and shelter.

Four species are common on our coasts, and these may be readily distinguished by the most cursory examination. The Serrated Wrack (F. serratus) has a flat, forked frond with toothed edges and a strong midrib, ranging from one to four feet long, and no air-vessels. The Knotted Wrack (F. nodosus—Plate VII.) may be known by its flattened, thick and narrow frond, without a distinct rib, from one to five feet long. The branches are narrow at the base, pointed at the tip, and are jointed to short projections on the main stem; and both these and the main stem have very large oval air-vessels. The spore-receptacles are mounted on slender stalks which arise from projections on the branches, and are of a bright yellow colour when mature. This species does not grow so near to high-water mark as do the others. Another species, the Twin-Bladder Wrack (F. vesiculosus—Plate VIII.)—is abundant everywhere along the coast, and is largely used by agriculturists both as manure and as fodder for cattle. The frond is flat, with a distinct midrib, and a non-serrated edge. Air-vessels are not always present, but when they are they usually occur in pairs, one on each side of the midrib, and are globular in form. The spore-receptacles are situated at the tips of the branches, are full of mucus, and are frequently forked. The last of the common species is the Channelled Wrack (F. canaliculatus—Plate VIII.), distinguished by a narrow frond, rounded on one side and channelled on the other. It has no midrib or air-vessels, and the fruit is contained in forked receptacles at the tips of the branches. This is the smallest of the genus, and may be found at all levels between the tide-marks. Stunted specimens may also be seen in situations where they are never submerged, but watered only by the spray of the highest tides.

The genus Himanthalia provides us with a single species (H. lorea) which is very peculiar on account of the small size of the frond as compared with the enormous dimensions of the spore-receptacles. The young frond is a pear-shaped sac which soon becomes flattened into a hollow disc. This disc then becomes solid, and concave above, and from its centre there arises a bi-forked, strap-like receptacle that often reaches a length of three or four feet, and may be mistaken for the frond of the weed by those who do not take the trouble to examine it. This weed is commonly known as the Sea Thong.

Belonging to the genus Cystoseira we have a few well-known weeds with conical disc-roots, and shrubby fronds with woody stem and alternate branches. The air-cells are in the substance of the frond, and the spore-receptacles at the tips of the branches. One of the species (C. ericoides) is of a heath-like habit, with a short, woody stem, and slender branches bearing hooked, leaf-like branchlets. Its air-cells are small, and are arranged singly near the tips of the branches; and the spore-receptacles are cylindrical, with hooked points. This weed is common on the south and west coasts, and may be readily distinguished by the beautiful iridescence it displays when in the water. C. fibrosa is very similar in general form, but is larger, and the air-vesicles are more conspicuous. It is not iridescent when in the water. A third species is named C. granulata from the rough and knobby appearance of the stem, due to numerous oval projections, from some of which spring the slender, much-divided branches. The air-vesicles are arranged in groups of two or three, and the spore-receptacles are at the ends of the branchlets. Our last example is C. fœniculacea, found on the south coast only, and readily distinguished by the numerous blunt spines that cover its long branches. The air-vesicles are narrow and pointed, and situated just below the forkings of the branchlets.

We conclude our résumé of the British sea weeds with a short description of the Podded Sea Oak (Halidrys siliquosa), which grows in the tide pools from high-water to low-water mark, the specimens inhabiting the shallow pools being only a few inches long, while those that grow in deep water often reach a length of three or four feet. It is an olive, shrub-like weed, with a conical, disc-like root that adheres very firmly to the rock, and a pinnately-branched frond with leaf-like branchlets. The air-vesicles are cylindrical and pod-like, divided internally into about ten cells, and the spores are contained in globular receptacles at the tips of the branchlets.

The young algologist will probably meet with many difficulties in his attempts to classify his sea weeds and name the various species in his collection. In dealing with an unknown weed we strongly recommend him to first determine the order to which it belongs. The genus should next be settled; and then, if possible, the species. It must be remembered, however, that he who has made himself acquainted with the principles of classification has done good work, and that it is far better to be able to arrange the weeds into properly-classified groups than to merely learn the names of the different species without regard to the relations which they bear to one another. The following table will probably assist the reader in the determination of the orders, but it must be remembered that a microscope will often be necessary for the examination of the spores and the minute structure of fronds.

CLASSIFICATION OF SEA WEEDS

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CHAPTER XVI
THE FLOWERING PLANTS OF THE SEA-SIDE

A considerable number of our flowering plants exhibit a decided partiality for the neighbourhood of the sea, and many are to be found only on the sea cliffs or in salt marshes not far from the shore. The principal of these will be now briefly described, dealing first with the monocotyledons, and then with the more highly organised dicotyledons.

The chief distinguishing features of these two groups have already been referred to, but it will be advisable here to give them in somewhat fuller detail.

The monocotyledonous plants, then, are those in which the stem is more or less woody and cylindrical, without either true bark or pith; and the woody tissue is not arranged in concentric rings, but in isolated bundles, which first bend inwards, as they rise, towards the centre of the stem, and then curve outwards towards the surface, which is hardened by the formation of a layer of hard woody matter. As a rule the stem is unbranched, and its growth takes place by a single bud at the summit. In nearly all of them the leaves are long and narrow, with veins running parallel throughout their length; and the parts of the flower are arranged in whorls of three or six. The outer whorl of the flower is often a conspicuous white or coloured perianth (that portion of the flower which lies outside the anthers), but in some the perianth is absent, the flower being protected by scaly bracts. The seeds are produced in a case called the ovary, and are fertilised by pollen grains which are developed in the anthers. When the pollen grains are set free they alight on the adhesive stigma, and grow, sending their tubes down into the ovary. The term monocotyledon is applied to these plants because the embryo has only one cotyledon or seed-leaf.

The principal divisions of this group are the Glumaceous Monocotyledons, in which the flower has no perianth, but is enclosed in scaly bracts or husks called glumes; and the Petaloid Monocotyledons, distinguished generally by the presence of a more or less conspicuous white or coloured perianth. The first of these includes the rushes, sedges, and grasses; and the other contains the lilies and orchids, with their allies, together with certain aquatic and semi-aquatic plants.

Among the Grasses there are several species that show a preference for the immediate neighbourhood of the sea, some growing luxuriantly at the bases of the cliffs where the beach is sandy, and others thriving best in salt marshes; but before dealing with these individually we shall note the general characteristics of the order (Gramineæ) to which they belong.

Grasses are distinguished by their jointed stems, which are usually hollow, with a split sheath, and bearing alternately arranged narrow leaves. The flowers, which are disposed either in spikes (sessile flowers arranged along a common axis) or in panicles (flowers stalked and arranged as in fig. 281), consist of scale-like bracts enclosing the stamens and the pistil. The bracts are in two series, the outer usually consisting of two glumes, and the inner of two pales; the upper pale, however, has two ribs running through it, and is therefore usually looked upon as a combination of two. In some species both glumes and pales are absent; but the former, when present, enclose one or more flowers, among which may be some that are abortive. The stamens are generally three in number, attached to the base of the flower; and the ovary is superior or free, that is, it grows above the other parts of the flower, and contains but one seed.

It will be convenient at this stage to refer briefly to the two principal methods by which the pollen of flowers is transferred to the stigmas for the purposes of fertilisation, and to see how various species are structurally adapted to the means by which the transfer is brought about.

Speaking generally, we may classify flowers into those which are fertilised by the wind (anemophilous flowers) and those in which the pollen is transferred by insects (entomophilous flowers). The former offer no attractions to allure the various forms of insect life. They are, generally speaking, very inconspicuous, being of small size and having no bright corollas. None of them are scented, nor do they produce the sweet nectar that forms the principal food of so many insects. Their anthers are borne on long filaments, so that they are exposed freely to the wind; and they produce abundance of pollen to compensate for the very wasteful method of wind-dispersion. The pollen, too, is not very adherent, so that it may be readily carried away by the breeze; and the plants concerned often produce their flowers early in the spring, before the leaves have appeared, thus giving the wind very free play.

Insect-fertilised flowers, on the other hand, are usually of attractive appearance; and, though often small and inconspicuous individually, they are in such cases grouped together in more or less showy clusters. They are also usually scented, and supply nectar and pollen to the insects which they allure. Some are fertilised by insects that fly by day, and these often close their petals on the approach of night, thus protecting their pollen during the period in which their fertilisers sleep. Others, fertilised by nocturnal insects, always spread their petals during the night, and generally protect their pollen from waste by sleeping throughout the day. As a rule, too, these night-bloomers have large and pale-coloured petals that are more easily seen by night; they also evolve a powerful scent to aid the insects in searching them out.

It will be seen that the economic relationship existing between flowers and insects is a mutual one, the latter visiting the former in order to obtain food, while the former derive in return the advantage of a direct transfer of pollen from flower to flower.

It is a well-known fact that the self-fertilisation of a flower often results in the development of very weak seedlings as compared with those that are produced by crossing; and it often happens that the pollen of a flower is incapable of producing the least effect when deposited on the stigma of the same bloom. In some cases the contact of the pollen of a flower with its own stigma will even act as a poison, causing the whole to shrivel and die; and truly wonderful are the varied means by which flowers contrive to secure a cross-fertilisation. It is here that the work of the wind and insects proves so valuable to flowers; but, in addition to this, a very large number of flowers are absolutely incapable of self-fertilisation, for the anthers and the stigma are not mature at the same time, or they exist in separate flowers, either on the same plant or on distinct plants of the same species. It is most interesting and instructive to study the many contrivances by which flowers compel certain insects to convey the pollen exactly in the way that best serves their purpose, sometimes even entrapping them after they have been allured, and not allowing them to escape until they are thoroughly dusted with the pollen which they are required to convey; but it is hardly our province to enter more fully into this matter in these pages.

An examination of the grasses will show at once that they are adapted for fertilisation by the wind. The flowers produce no nectar; and, consistently, develop no bright petals and evolve no odours to attract insects. On the other hand, their anthers produce abundance of lightly-adhering pollen, and are mounted on long filaments which hold them well exposed to the wind; and the stigmas are well adapted for catching the scattered grains, being long and protruding, and often covered with sticky hairy or feathery appendages.

Although the flowers of grasses are generally wanting in attractive colours, the clusters of blossoms are often very graceful and pretty, especially when the large anthers, covered with bright-yellow pollen, dangle in the breeze.

We will now briefly describe the principal British grasses that grow chiefly or exclusively in the immediate neighbourhood of the sea.

The Sea Hard Grass (Lepturus filiformis) is a perennial species, usually about six inches in height, very common on some sandy coasts, and found in flower during the hottest months of the summer. The flowers are arranged in simple spikes, on slender erect stems; and the glumes, which are united at their bases, enclose a single bloom.

In similar situations we may find the Sea Lyme Grass (Elymus arenarius), a tall species, often reaching a height of four feet, with glaucous rigid leaves. The flowers are arranged in a simple spike, but the spikelets are clustered two or three together. This species flowers in August.

Of the well-known Barley Grasses there is one species (Hordeum maritimum) that has its habitat along the coast. Like the others of its genus, the spikelets are arranged in threes, each bearing a single flower, and the pales have long slender processes (awns) which constitute the so-called beard. It also resembles the common Meadow Barley Grass in having the middle flower of each three perfect, while the two laterals are abortive, but may be distinguished by its rough and bristly glumes, and the semi-oval form of the pales of the lateral flowers. It is a somewhat stunted species, sometimes only five or six inches in height, and may be found in flower about Midsummer.

The Brome Grasses have also a representative of a sea-loving nature, which is to be found in fields near the cliffs. It is the Field Brome Grass (Bromus arvensis), an annual grass that grows to a height of two or three feet. Brome grasses generally are known by their loose panicles of flowers, lanceolate and compressed spikelets, and awned florets enclosed in unequal glumes; and B. arvensis may be distinguished by its hairy leaves and stem-sheath, and the drooping panicle with the lower peduncle branched.

Among the Meadow Grasses we have three or four coast species. In these the florets are in panicles and are not awned. The outer glumes are keeled and traversed by several veins; and the lower pales are also keeled, with five or more nerves. The Sea Meadow Grass (Poa maritima) grows in salt marshes near the sea, its erect rigid panicles reaching a height of about eight or ten inches. It has a creeping root, and its leaves are curved inward at the margins. The Procumbent Meadow Grass (P. procumbens) and a variety of the Reflexed Meadow Grass (P. distans) are also plentiful in salt marshes. The former may be known by the short rigid branches of its panicle and the five ribs of the lower pales; and the latter is much like P. maritima, but grows taller, and its spikelets are crowded. The Wheat Meadow Grass (P. loliacea) grows on sandy shores. Its spikelets are arranged singly and alternately along the central axis, and the upper glume reaches to the base of the fourth floret. This species flowers in June, but the other three of the same genus bloom from July to September.

The reader is probably acquainted with the Fescue Grass, with its awned flowers arranged in one-sided panicles. There are no less than seven species, one of which—the Single-husked Fescue (Festuca uniglumis)—grows on sandy shores, flowering in June and July, and reaching a height of from nine to twelve inches. The panicles are upright and unbranched, and the species may be readily known by the flowers, which are compressed, with long awns, and with the lower glumes wanting.

Knappia agrostidea is a dwarf species, rarely exceeding four inches in height, that is found on certain sandy shores, but is very local. Its flowers are arranged in a simple spike, the spikelets being solitary and unilateral, with only a single flower, and the pales are shaggy. The plant has several stems which bear short, rough leaves.

The Mat Grass or Sea Reed (Ammophila arundinacea) is common on many sandy coasts, where it grows to a height of three or four feet, and flowers in July. The white flowers are clustered in dense cylindrical, pointed spikes; and the leaves are of a glaucous green colour, rigid, and curved inward at the edges.

Dog’s-tooth Grass (Cynodon dactylon). This species has a creeping root, and the leaves are downy on the under side. The flowers are arranged in a compound spreading spike, of three to five parts, and the spikelets are of a purplish colour, ovate in form, and arranged in pairs. The glumes are equal in size. It is found on sandy shores, grows to a height of about six inches, and flowers in July.

A species of Canary Grass (Phalaris arundinacea) is also to be seen on sandy coasts. Unlike the other species of the same genus, its flowers form an erect spreading panicle, and the glumes are not keeled. It is also taller than the common canary grass of waste places, often reaching a height of three feet, and is commonly known as the Reed Canary Grass.

The Sea Cat’s-tail Grass (Phleum arenarium) is common on many coasts. It is much smaller than the common species of Cat’s-tail, being generally less than a foot high. The spike is of an elongated oval form, blunt at the tip and narrow at the base; and the glumes are narrow, pointed at both ends, and fringed. Each spikelet has but one flower.

In salt marshes we occasionally meet with the Perennial Beard Grass (Polypogon littoralis), but it is somewhat rare. It has a creeping root, and the flowers form a somewhat dense spike-like panicle. The glumes have a slender awn. It grows to a height of one to two feet, and flowers in July.

The Tuberous Fox-tail Grass (Alopecurus bulbosus) is another rare grass of the salt marshes, where it grows to the height of twelve to sixteen inches, flowering in May and June. The genus to which it belongs is very closely allied to Phleum, but may be distinguished by having only one pale to each flower, and this species has a long awn attached to the back portion. The panicle, too, is cylindrical and slender, the glumes quite free and abruptly pointed, and the awns longer than the pales.

The last of the sea-side grasses are two rare species of Cord Grass (Spartina), both of which are found in salt marshes. In these the inflorescence is a compound spike, with one-sided spikelets inserted in a double row. The glumes are keeled and pointed; the pales cleft, pointed and without awns; and the styles two in number, very long. The only British species of the genus are the two (S. stricta and S. alternifolia) referred to above. They both grow to a height of about eighteen inches, and flower in late summer. In the former the spikes number two or three, and are longer than the leaves; and the outer glume is hairy, with a single nerve. The latter, which is the rarer of the two, bears several spikes, shorter than the leaves; and the outer glume has five nerves.

Certain of the sedges (order Cyperaceæ) are also more or less familiar to the sea-side naturalist, and must therefore receive a small share of our attention. In general terms these are grasslike, monocotyledonous plants, the stems of which are solid, jointed, and frequently angular. The leaves are very similar to those of grasses, except that the sheaths, which surround the stem, are not split. The flowers are generally arranged in a spike, overlapping each other, and each one supported on a scale-like bract. In some sedges the flowers are perfect, each one possessing both stamens and pistil; but in some species the flowers are unisexual, some bearing stamens and no pistil, and others pistil only. The stamens are generally three in number, the ovary is superior, and the stigmas either two or three.

Sedges abound in moist places, some being peculiar to salt marshes, while others grows on sandy shores; and a few of the British species of the latter habitat are often so abundant that their creeping roots bind the sand together, effectually holding it in place while the surrounding portions of the beach are mercilessly driven by the wind.

A few of the sea-side sedges belong to the genus Carex, in which the flowers are imperfect, and the fruit is enclosed in the outer parts of the flower. C. extensa thrives in salt marshes, growing to a height of a foot or more, and flowering about midsummer. Its fertile flowers form oblong erect spikelets, while the barren spikelets are solitary. The bracts are long and leafy, with short sheaths surrounding the stem. The leaves are curved in at the edges, and the fruit is oval and ribbed, with a short straight beak.

On sandy shores the Sea Sedge (C. arenaria) is often common, and its underground stems are used for sarsaparilla. It is a perennial species, growing to a height of about nine inches, and flowering in June and July. The flowers grow in an oblong interrupted spike, the upper spikelets being barren, and the intermediate ones barren at the tip. The fruit is oval, veined, and winged.

Another species of this genus—the Curved Sedge (C. incurva) —is sometimes to be seen on sandy shores, but it is rare, and is also a very small sedge, growing only to a height of about three inches. It derives its specific name from its curved stem, and may be further distinguished by its channelled leaves and the globular mass of spikelets which are barren on the top.

Some of the so-called rushes belong to the same order as the sedges, and a few of these are more or less restricted to the neighbourhood of the sea. The Salt-marsh Club Rush (Scirpus maritimus), as its name implies, is to be found in marshes near the sea. It is very variable in height, ranging from one to three feet, and displays its dense terminal cluster of spikelets in July and August. In this genus all the flowers are perfect, the glumes imbricated and bristled; and the present species may be distinguished by the glumes being divided into two sharply pointed lobes. A variety of S. lacustris may also be found on the sea shore, but it is somewhat rare. It has a leafless glaucous stem, and flowers arranged in compound spikes. The glumes are rough, and contain a compressed fruit.

A very small species of the Spike Rush (Eleocharis parvula), growing only one or two inches high, is sometimes found on the muddy shores of Ireland. It has perfect flowers, in a single terminal spikelet. The leaves are very narrow, growing from the base of the plant; and the round stem is enclosed in a single leafless sheath.

The true rushes belong to the order Juncaceæ. These have fibrous roots and narrow leaves, and bear clusters of brown flowers. The perianth consists of six parts, and the stamens are usually six in number. The ovary is generally three-celled, developing into a three-valved capsule. The Lesser Sea Rush (Juncus maritimus) is common in salt marshes, growing to a height of two or three feet, and flowering in July. It has a rigid leafless stem, bearing lateral clusters of flowers. The segments of the perianth are very narrow and sharp, and the seeds are enclosed in a loose testa. Closely allied to this species is the Great Sea Rush (J. acutus), which grows three or four feet high on sandy shores. In general characteristics it resembles J. maritimus, but the segments of the perianth are oval and have thin transparent margins; and it is a much rarer species.

We now pass to the peculiar Sea Grasses or Grass Wracks (Zostera) which grow in salt water. They belong to the order Naiadaceæ, and are characterised by cellular leaves with parallel veins, and inconspicuous unisexual or bisexual flowers. The perianth, when present at all, consists of two or four scale-like parts, and the stamens correspond in number with these. The ovary is free, and the carpels, one or more in number, contain each a single ovule. In Zostera the flowers are imperfect, and seem to grow in the slit of the leaf. There are two species, both of which grow in shallow water close to the shore, often in such dense masses that they impede the progress of boats. They have long creeping stems that lie buried in the sand, giving off numerous root-fibres, and send up to the surface slender branches that bear grass-like leaves. The flowers are unisexual, and are arranged in two rows on the same side of a flattened stalk that is enclosed in a sheath formed by short leaves. They have no perianth, the male flowers being composed of a single anther, and the female of a one-celled ovary containing a single ovule, and surmounted by a style with two long stigmas.

There are two species—the Broad-leaved Grass Wrack (Z. marina) with leaves one to three feet long and traversed by three or more parallel veins, and the Dwarf Grass Wrack (Z. nana), the leaves of which are less than a foot long, with veins numbering one to three. There is a variety of the former, however, named Angustifolia, in which the leaves are much narrower than usual, and the veins fewer in number.

The order Alismaceæ, which contains the water plantains, arrow-heads, and other semi-aquatic plants, has a representative of marine tendencies in the Sea-side Arrow Grass (Triglochin maritimum). The flowers of this order are bisexual, with six stamens and a six-parted perianth. The fruit consists of many carpels; and, although the plants are monocotyledons, their leaves have netted veins; and altogether they somewhat resemble the ranunculaceous exogens. The Sea-side Arrow Grass is abundant in some salt marshes, growing to a height of about a foot, and produces loose simple spikes of green flowers all through the summer. The leaves are radical, narrow and fleshy; and the ovary consists of six carpels.

Of the interesting order Liliaceæ we have only one plant of the coast, and even that—the Asparagus—is not by any means generally common. It is the same plant that is so largely cultivated as an article of diet, and which is so highly valued on account of its diuretic properties. It is moderately common on parts of the south coast, particularly in the Isle of Portland and in West Cornwall, and its general appearance is so graceful that it is largely employed as an ornamental garden plant. The stem is erect and freely branched, bearing feathery bunches of bristled leaves and pale-yellow axillary flowers. As is the case with the Liliaceæ generally, the flowers are bisexual, with a six-parted perianth, six stamens, and a three-celled superior ovary; and the last named, in the Asparagus, forms a bright-red berry in the autumn.

We have now to leave the monocotyledonous plants and pass on to the dicotyledons, which form the most highly developed of the primary divisions of the vegetable kingdom. A few of the general characteristics of this group have already been given, but we must now look rather more closely into the nature of the plants included.

The class receives its name from the presence of two cotyledons or seed-leaves in the embryo plant, and is also known as the Exogenæ because the stems increase in thickness by the addition of zones of woody tissue at the exterior. When the young dicotyledonous plant first appears above the ground, the two cotyledons, which formerly served to shelter the immature bud, usually appear as tiny fleshy leaves; but these soon wither away, while the bud produces the more permanent leaves that are of a very different structure. A section of the stem will reveal distinct pith, wood, and bark, the wood being more or less distinctly divided into wedge-shaped masses by rays from the pith; and, in the case of perennial stems, the wood is arranged in concentric rings, the number of which correspond approximately with the years of growth. The leaves of exogens have their veins in the form of a network, and the parts of the flower are generally arranged in whorls of two or five or of some multiple of these numbers.

The flowers always have stamens and pistil, but in some these organs exist in separate flowers, either on the same plant, or on different plants of the same species, and the ovules are nearly always contained in a case called the ovary.

Dicotyledons are divided into three main groups, the division being based on the structure of the flowers. They are the Apetalæ in which the petals are absent, but the perianth is frequently petaloid, though it is occasionally also absent; the Gamopetalæ, in which the petals are united; and the Polypetalæ, in which the petals are always distinct.

Dealing with these divisions in the above order we come first to the Spurges, three species of which occur on sandy shores. They belong to the order Euphorbiaceæ, which includes, in addition to the spurges, a number of herbs, trees, and shrubs with entire leaves often a milky juice, and small flowers, sometimes enclosed in calyx-like bracts. The flowers may have one or several stamens, and the perianth, if present, consists of three or four parts; but perhaps the best distinguishing feature of the order is the nature of the fruit, which separates elastically into three carpels.

The Sea Spurge (Euphorbia Paralias) is commonly seen on sandy shores, where its yellow flowers bloom in late summer and in autumn. It may be distinguished among the numerous species of the genus by its narrow oblong imbricated leaves, of a tough leathery nature, the broad heart-shaped bracts, and the wrinkled capsules containing smooth seeds. The Portland Spurge (E. portlandica) is a similar plant, found in similar situations, and flowering from May to September. Its leaves are oval and narrow, obtuse, and of a glaucous colour, and the bracts are more triangular than those of the last species. The capsules are slightly rough, as are also the seeds. There is yet another sea-side spurge—the Purple Spurge (E. peplis)—a somewhat rare plant, found on some of the sandy shores of the south of England. It grows to about eight or nine inches in length, and blooms in late summer, the flowers, like those of most of the spurges, being yellow. The stem is of a glaucous colour, and trails along the ground; the leaves are opposite and somewhat heart-shaped, and the flowers solitary. This species may be distinguished from other spurges by its stipuled leaves.

On sandy cliffs we sometimes meet with the Sea Buckthorn (Hippophaë rhamnoides)—a spiny shrub, ranging from about two to seven feet in height, the bark of which is covered with a silvery scaly scurf that forms a beautiful object for the microscope. It is the British representative of the Oleasters (order Eleagnaceæ). The leaves are alternate, lanceolate, with a silvery surface; and the flowers are small, green and unisexual. The male flowers grow in catkins, each arising from a scaly bract, and have a green perianth. The female flowers have a tubular perianth, and a free one-celled ovary. The latter forms a hard nut-like fruit, which is surrounded by a succulent mass formed by the former. This shrub flowers in the spring, while the leaves are still very small.