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OF THE HARDY LIGNEOUS PLANTS OF the order BETULA`CEÆ.
THESE are included in two genera, the characters of which are thus given by Smith: ALNUS Tourn. Barren flowers numerous, aggregate, in a loose cylindrical catkin, imbricated every way. Calyx a permanent wedge-shaped scale, 3-flowered, with 2 very minute lateral scales. Corolla composed of 3 equal florets, attached to the inner side of every scale, each of one petal, in 4 deep, equal, ovate, obtuse segments. Filaments 4, from the tube of the corolla, shorter than its segments, and opposite to them. Anthers of 2 round lobes.-Fertile flowers fewer, aggregate, in an oval firm catkin, imbricated every way. Calyx a permanent, wedge-shaped scale, 2-flowered. Corolla none. Germen compressed, of 2 cells. Styles 2, parallel, tapering, a little prominent, deciduous. Stigma simple. Nut ovate, bony, compressed, angular, without wings, of 2 cells. Kernels solitary, ovate, acute.-Trees, with leaves alternate, stalked, simple, wavy or cut, deciduous, with twin deciduous stipules. Catkins terminal, panicled, pendulous, earlier than the foliage. (Eng. Fl., iv. p. 134.) Natives of Europe and North America.
BE'TULA Tourn. Barren flowers. Catkin cylindrical, lax, imbricated all round with ternate concave scales; the middle one largest, ovate. Corolla none. Filaments 10-12, shorter than the middle scale, to which they are attached. Anthers roundish, 2-lobed.— Fertile flowers. Catkin similar, but more dense; scales horizontal, peltate, dilated outwards, 3lobed, 3-flowered. Corolla none. Germen compressed, bordered, of 2 cells. Styles 2, awl-shaped, downy. Stigma simple. Nut oblong, deciduous, winged at each side, of one cell, with a solitary kernel.-Trees or shrubs, very hardy, with round slender branches; scattered, stalked, simple, serrated, deciduous leaves; and a hard, often veiny, wood. Bark, in several species, of many fine, soft, membranous layers. (Eng. Fl., iv. p. 153.) Natives of Europe, North America, and Asia.
The alder and the birch were made separate genera by Tournefort, and by Linnæus also, in his earlier works; but he afterwards united both genera into one, under the name of Bétulus. Modern botanists, for the most part, follow Tournefort; and the following are the distinctive characteristics of his two genera:-In Bétula, the female catkins are cylindrical, solitary, on simple peduncles, and bear their seeds furnished with a membrane on each side. In Alnus, the female catkins are oval; and they are borne on a branchy peduncle, containing seeds which are not bordered with membranes. As secondary characteristics, the birches prefer dry places, and the alders moist situations. All the known species of alder may be reduced to three or four; and all the species of birch which are hardy in England to four or five. Most of the species of both genera flower and fruit freely in the climate of London.
A'LNUS Tourn. THE ALDER. Lin. Syst. Monc`cia Tetrándria. Identification. Tourn., t. 359.; Willd. Sp. Pl., 4. p. 334.; Hall. Hist., 2. p. 300.; Comp., ed. 4., p. 176.; Gærtn., t. 90.
Synonymes. Bétulæ species Lin.; Aune, Fr.; Erle, Ger.; Ontano, Ital.; Aliso, Span. Derivation. From al, near, and lan, the edge of a river, Celtic; in reference to its habitat : from the Hebrew, alon, an oak: or, according to others, from álitur amne, it thrives by the .river.
Description, &c. Trees, rarely exceeding the middle size; and some so low as to be considered shrubs. With the exception of A. glutinosa laciniàta and A. cordifòlia, the species are not very ornamental; nor is the timber of great value, except for the charcoal which may be made from it. All the species prefer a moist soil, or one in the vicinity of water. A. glutinosa ripens seeds freely, as do most of the other sorts; but all the latter are generally propagated by layers. The only truly distinct species appear to us to be, A. glutinosa, A. cordifòlia, A. incàna, A. oblongata, and A. víridis; which last seems an intermediate species, or connecting link, between A'lnus and Bétula.
1. A. GLUTINO'SA Gartn. The glutinous, or common, Alder.
Identification. Gærtn., 2. p. 54.; Willd. Sp. Pl., 4 p. 334.; Comp., ed. 4., p. 155.; Hook. Lond., t. 59., Scot., 271.; Hoss. Anleit., 186.; Lodd. Cat., ed. 1836.
Synonymes. Bétulus A'lnus Lin. Sp. Pl., 1394. a, Fl. Br., 1013., Eng. Bot., 21. t. 1508.; B. emar. ginata Ehrh. Arb., 9.; Alnus Raii Syn., 442.; Aune, Fr.; gemeine Else, or Elser, or schwartz Erle, Ger.'; Elsenboom, Dutch; Alno, or Ontano, Ital.; Aliso, or Alamo nigro, Span.
Engravings. Eng. Bot., t. 1508.; Hunt. Evel. Syl., 240. f.; Ger. Emac., 1477. f.; Lob. Ic., 2. 191. f.; Loes. Pruss., t. 1.; Dalech. Hist., 97. f.; our fig. 1540.; and the plate of this species in our last
Spec. Char., &c. Leaves roundish, wedge-shaped, wavy, serrated, glutinous, rather abrupt; downy at the branching of the veins beneath. (Eng. Fl., iv. p. 131.) A tree, from 30 ft. to 60 ft. high; a native of Europe, from Lapland to Gibraltar; and of Asia, from the White Sea to Mount Caucasus; and, also, of the north of Africa; flowering, in Britain, in March and April. Varieties.
A. g. 2 emarginata Willd. Baum., p. 19.,
St. Germain, where the stool still remains from which all the nurseries of Paris have been supplied with plants, and, probably, all Europe. A. g. 4 quercifolia Willd., l. c., Lodd. Cat., ed. 1836.-Leaves sinuated, with the lobes obtuse.
A. g. 5 oxyacanthafolia; A. oxyacanthæfòlia Lodd. Cat., ed. 1836; and our fig. 1539.-Leaves sinuated and lobed; smaller than those of the preceding variety, and somewhat resembling those of the common hawthorn.
A. g. 6 macrocárpa; A. macrocárpa Lodd. Cat., 1836; has the leaves and fruit rather larger than those of the species, and is also of more vigorous growth.
A. g. 7 foliis variegatis Hort. has the leaves variegated.
Other Varieties. There are some other names applied to plants in the collection of Messrs. Loddiges, which, we think, can only be considered as varieties of A. glutinòsa; or, perhaps, of A. incàna; but the plants are so small, that we are unable to determine whether they are sufficiently distinct to be worth recording. Among these names are, A. nigra, A. rubra, A. plicata, and A. undulata. A. rùbra is said to be a native of the Island of Sitcha. (Annal. des Scien. Nat., 3. p. 237.) Some of the sorts treated as
species we think only varieties, as we have indicated by putting the letter g. in parentheses.
Description. The alder, in a wild state, even in favourable situations, is seldom seen higher than 40 ft. or 50 ft.; but in uncultivated grounds, and in good soil near water, it will attain the height of 50 ft. or 60 ft., and upwards. This is not only the case with the species, but with the variety A. g. laciniata, which forms a handsome pyramidal tree; which, at Syon, has attained the height of 63 ft., and at Woburn Farm, near Chertsey, is still higher. The bark of the common alder, in oldish trees, is nearly black, and full of clefts; the colour of the wood is white before the tree is cut down; but, immediately on being cut, the surface of the wound becomes of a deep red; soon fading, however, into the pale flesh-colour, which the whole of the wood of this tree, when cut down, takes when dry, and retains ever afterwards. The wood is homogeneous, tender, and without much tenacity. The branches, when they are young, and the tree is in a state of vigorous growth, have a triangular form; but, when mature, they are round. The bark, at the rising of the sap, separates from the wood with very great facility. The leaves, when in the bud, are folded in the manner of a fan, very glutinous, and completely enclosed by two oblong stipules of a whitish green. They are from 3 in. to 4 in. long, and nearly as broad. The petiole is about 1 in. long, and prolonged on the disk of the leaf, in the form of a very prominent nerve on the under side, from which proceed to the right and left other prominent nerves, in each of the axils formed by which is a little tuft of cottony hair. The characteristics of the leaves of this species, as compared with those of other species of the genus, and especially of A. incàna, is, that they are always rounded at the summit, and never pointed; though this distinction does not hold good when applied to some of the
varieties, such as A. g. laciniata. The leaves are of a deep dark green; and both the young shoots and leaves are covered with a glutinous substance, more especially in the early part of summer. The male catkins are cylindrical, like those of the birch, and appear in the autumn; while the female ones, which are on branched footstalks, are of a short conical form, like a small fir cone, and are produced in spring along with the leaves. On Mount Caucasus, Pallas informs us, the female catkins come out about the end of February; but, in the north of Russia, in March and April. The rate of growth of the alder, in a favourable soil and situation, is about 2 ft. or 3 ft. a year for four or five years; so that a tree 10 years planted will frequently attain the height of 20 ft. or 25 ft.; and at 60 years the tree is supposed to have arrived at maturity. The roots are creeping; and sometimes, but rarely, they throw up suckers. The shade and fallen leaves of this tree are not injurious to grass.
Geography, History, &c. The common alder is the most aquatic of European trees, being found in wet swampy grounds, throughout the whole of Europe, in situations too moist for even the willow and the poplar. In meadows, and by river sides in the plains, it becomes a considerable tree; but on mountains, and in the most northerly parts of Sweden, it diminishes to a shrub. It is found in the west, east, and north of Asia and in the north of
Africa. According to Pursh, the common alder is also a native of North America; in the interior of Canada, and on the north-west coast. The alder was known to Homer and Theophrastus. (See p. 18.) According to Virgil, it formed the first material for boats; and Lucan recommends it as a wood proper for ship-building. Virgil describes the proper situation for it, as on the margin of still waters; and Vitruvius recommends the wood for piles, stating that the city of Ravenna was built on it. Aristotle mentions that the alder was generally barren in Greece, and only fertile in the island of Crete; but it may be doubted whether he alludes to the same tree. In the time of Theophrastus, the bark was used for dyeing leather; and, in the days of Pliny, the wood was employed for piles, which he calls "eternal;" and for pipes, for conveying water under ground, as it is at present. The same author states that the tree was planted along the banks of rivers, to prevent them, by its numerous roots and suckers, from being washed away during extraordinary floods. Evelyn tells us that the celebrated bridge of the Rialto, at Venice, was built on piles of this tree. It is still extensively used in Flanders and Holland, for the purpose of forming piles. Boutcher, writing in 1780, informs us that, between 1730 and 1750, "vast quantities of alder plants were brought from Holland to Scotland, at a considerable price, and unhappily for the owners, planted in large tracts of moist land, from which no returns suitable to the labour and expense had been received." He adds that he would greatly have preferred "poplars and abeles." (Treatise, &c., p. 111.)
Properties and Uses. Naturally, the leaves of the alder afford food to the larvæ of different species of moths, and other insects; and the leaves and young shoots are eaten by horses, cows, goats, and sheep, though they are not fond of them; and they are refused by swine. Among the lepidopterous insects may be mentioned several species of the genus Hipparchia Fab. Satúrnia Schrank. (See Magazine of Natural History, vol. viii. p. 210., and vol. v. p. 251.) Clytus álni Fab., a coleopterous insect, is common in the trunks of old alder trees. C. Arìetis Fab., Cerambyx Arìetis L., Sam. pl. 2. f. 25., and our fig. 1541., is also common. The tongues of horses feeding upon the alder, Linnæus observes, are turned black; and, on that account, it is supposed by some persons to be unwholesome for them. The uses to which the alder has been applied by man are various. The wood, though soft, is of great durability in water. It weighs, when green, 62 lb. 6 oz.; half-dry, 48 lb. 8 oz.; and quite dry, 39 lb. 4 oz., per cubic foot; thus losing above a third of its weight by drying, while it shrinks about a twelfth part of its bulk. In the Dictionnaire des Eaux et Forêts, the wood is said to be unchangeable either in water or earth. It is used for all the various purposes to which soft homogeneous woods are generally applied; viz. for turnery, sculpture, and cabinet-making; for wooden vessels, such as basins, plates, and kneading-troughs; for sabots, wooden soles to shoes and pattens, clogs for women, and similar purposes. In France, sabots made of alder wood are smoked, to render them hard and impervious to the larva of the beetle which attacks that wood. The French, and also the Highlanders, are said to make light chairs of the wood of this tree, which have the colour, though they have not the grain, of mahogany. Sir Thomas Dick Lauder, speaking of the wood, says, "It is extremely valuable, even when of a small size, for cutting up into herring-barrel staves; and thus whole banks, in Scotland, have been denuded every year of this species of timber. The old trees, which are full of knots, cut up into planks, have all the beauty of the curled maple, with the advantage of presenting a deep, rich, reddish tint; and, in this state, they make most beautiful tables. It must be remembered, however, that the alder timber is liable to be perforated by a small beetle; it should, therefore, if possible, be prepared by immersing the logs in a large hole dug in a peat moss, and impregnating the water of the hole with a quantity of lime. If this be done for
a few months, and the furniture afterwards well varnished over with what is called the French polish, it will stand unharmed for generations." (Lauder's Gilpin, vol. i. p. 137.) Wood of alder, which has lain a long time in peat bogs, becomes as black as ebony; and as, in a recent state, it readily receives a black dye, while, from the homogeneousness of its texture, it will take a better polish than soft woods do generally, it forms a very common substitute for that wood in small articles; but it has always a dull hue, being incapable of receiving the lustre of the real ebony. When used in constructions above ground, it ought only to be placed in situations where it will be kept perfectly dry but the great use of the wood, on a large scale, is for piles, as foundations for bridges and other buildings, water-pipes, barrels of pumps, and props for mines. The spray is more durable than that of most other trees, when used for filling drains in moist soil. Dorsetshire woodwards (woodmen), Mitchell observes," have nearly the same adage applied to alder poles, when peeled for rafters, as those of the midland counties have for willows and poplars (see p. 1637.); viz:
"Thatch me well, and keep me dry,
"Stakes of alder," he says, " will not stand twelve months, nor will the timber do for posts, or anything else, where it is in contact with the ground, except under water. The wood, however," he adds, "ought not to be entirely rejected;" and he recommends it as linings for stone-carts and wheelbarrows, that are in constant use; 66 because, being soft, though it may bruise, it does not split by the stones being tumbled in.' It makes better weather-boards than elm or beech, because it does not warp or cast. (Dendrol., p. 55.) Alder hop-poles, according to Cobbett, will only last one year. As fuel, the alder is to the beech as 985 is to 1540: but, like other woods of little value as fuel for heating dwelling-houses, it is preferred for other purposes, where a slow and not fierce heat is required; such as for heating bakers' ovens, for burning limestone and chalk, for burning bricks, &c. The charcoal is esteemed excellent for making gunpowder; but for domestic uses it is considered inferior, being to that of the beech as 885 is to 1600. The ashes yield at the rate of 65lb. of potash to 1000 lb. of ashes; which ranks it among 73 other woods that yield this salt, in the 67th degree. The bark on the young wood is powerfully astringent, and is employed by tanners: and the young shoots are used both for tanning, and dyeing red, brown, and yellow; and, in combination with copperas, to dye black. The catkins dye green; and the female catkins are used by fishermen to sustain their nets above water, instead of cork. In Hall's Travels in Scotland, the author says that the country people in the Highlands make their own shoes; and, to avoid the tax on leather, privately tan the hides with the bark of birch and alder. (Travels in Scotland, vol. ii. p. 401.) The fresh wood dyes a snuff-colour; and the bark, dried and powdered, and mixed with logwood, bismuth, &c., yields the colour called boue de Paris. It is said that the Laplanders masticate the bark, and, with the saliva so coloured, stain their leathern garments red. (Syl. Sketches, p. 9.) In France, the small roots are split, and worked into baskets; and the knotty parts of the larger roots are used for inlaying cabinet-work. Both linen and woollen cloths are dyed black by boiling them with the flowers, buds, female catkins, bark, and spray, and afterwards putting them into water which has been used at a smith's forge for quenching the red-hot iron. The leaves are used in medicine as detersive; and they are employed in decoctions and gargles for diseases of the throat. Among the uses which may be considered obsolete, are two mentioned by Pennant; viz. spreading the boughs over the fields during summer; leaving them there during the winter to rot; and, in the following March, clearing off the undecayed parts, and ploughing the ground for a crop of corn. The other use is that of strewing the leaves and young shoots on the floors of houses to attract fleas, which are said to be entangled in the "tenacious liquor, as birds are by birdlime."