229. _The ALDER, or OWLER_ (Betula alnus, Fig. 63), _is a tree which grows in wet situations, and is distinguished by its flower-stalks being branched, and its leaves being roundish, waved, serrated, and downy at the branching of the veins beneath._ There are few means of better employing swampy and morassy grounds than by planting them with alders; for although the growth of these trees is not rapid, the uses to which they are applicable are such as amply to repay the loss of time requisite before they come to perfection. The _wood_ of the alder, which is in great demand for machinery, is frequently wrought into cogs for mill-wheels, and is peculiarly adapted for all kinds of work which are to be constantly kept in water. It is consequently used for pumps, sluices, pipes, drains, and conduits of different description, and for the foundation of buildings situated in swamps. The water pipes which are laid under the streets of many of our large towns are made of alder; and, for its utility in the formation of sluices, it is much cultivated in Holland. It is commonly used for bobbins; and women's shoe-heels, ploughmen's clogs, and numerous articles of turnery ware, are formed of it. This wood serves also for many domestic and rural uses, for spinning-wheels, troughs, the handles of tools, ladders, cart-wheels; and, as coppice wood, it is planted to be cut down every ninth or tenth year, for poles. The roots and knots furnish a beautifully veined wood, nearly of the colour of mahogany; and well adapted for cabinet work and furniture. The _bark_ may be advantageously used in the operations of tanning and leather-dressing; and by fishermen, for staining their nets. This, and the young twigs, are sometimes employed in dyeing, and yield different shades of yellow and red. The Laplanders chew the bark of the alder, and dye their leather garments red with the saliva thus produced. With the addition of copperas, it yields a black dye, which the dyers of cotton use to considerable extent; and, for this purpose, it is purchaseable in some countries, at the rate of seven pence or eight pence per stone. In the highlands of Scotland, we are informed that _young branches_ of the alder, cut down in the summer, spread over the fields, and left during the winter to decay, are found to answer the purpose of manure. The fresh gathered _leaves_, being covered with a glutinous moisture, are said to be sometimes strewed upon floors to destroy fleas, which become entangled in it, as birds are with bird-lime. But these agile and troublesome insects must be numerous indeed to render the setting of traps for them of any avail towards their destruction. 230. _The COMMON NETTLE. There are two kinds of nettle common in England, one of which_ (Urtica dioica) _has heart-shaped leaves, and the other_ (Urtica urens) _has oval leaves._