CHAP. CIV.
IJETULA'CE.®:. ^LNUS.
1677
CHAP. CIV.
OF THE HARDY LIGNEOUS PLANTS OF THE ORDER EETULA'CEiE.
These are included in two genera, the characters of which are thus givenby Smith : —
iTlnus Tourn. Barren flowers numerous, aggregate, in a loose cylin-drical catkin, imbricated every way. Calyx a permanent wedge-shapedscale, 3-flowered, with 2 very minute lateral scales. Corolla composed of3 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 ofthe corolla, shorter than its segments, and opposite to them. Anthers of2 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, taper-ing, 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, decidu-ous, with twin deciduous stipules. Catkins terminal, panicled, pendulous,earlier than the foliage. {Eng. FI., iv. p. 134.) Natives of Europe andNorth America.
.Se'tela Tourn. Barren flowers. Catkin cylindrical, lax, imbricated allround with ternate concave scales; the middle one largest, ovate. Co-rolla none. Filaments 10—12, shorter than the middle scale, to whichthey are attached. Anthers roundish, 2-lobed. — Fertile flowers. Catkinsimilar, but more dense; scales horizontal, peltate, dilated outwards, 3-lobed, 3-flowered. Corolla none. Germen compressed, bordered, of 2cells. Styles 2, awl-shaped, downy. Stigma simple. Nut oblong, decidu-ous, winged at each side, of one cell, with a solitary kernel. — Trees orshrubs, very hardy, with round slender branches; scattered, stalked, simple,serrated, deciduous leaves; and a hard, often veiny, wood. Bark, inseveral species, of many fine, soft, membranous layers. {Eng. FI., iv.p. 153.) Natives of Europe, North America, and Asia.
The alder and the birch were made separate genera by Tournefort, and byLinnaeus also, in his earlier works; but he afterwards united both generainto one, under the name of jftetulus. Modern botanists, for the mostpart, follow Tournefort; and the following are the distinctive character-istics of his two genera: — In Aetula, the female catkins are cylindricalsolitary, on simple peduncles, and bear their seeds furnished with a mem-brane on each side. In A'lnus, the female catkins are oval; and they areborne on a branchy peduncle, containing seeds which are not borderedwith membranes. As secondary characteristics, the birches prefer dryplaces, and the alders moist situations. All the known species of aldermay be reduced to three or four; and all the species of birch which arehardy in England to four or five. Most of the species of both generaflower and fruit freely in the climate of London.
Genus I.
A'LNUS Tourn. The Alder. Lin. Syst. Monae' cia Tetrandria.
Identification. Tourn., t. 359.: Willd. Sp. FI., 1 . p. 334.: Hall. Hist., 2. p. 300.: Comp., ed. 4.,p. 176.; GiErtn., t. 90.
Synonymes. -Betul® species Lin. ; Anne, Fr. ; Erie, Ger. j Ontano, Ital. j Aliso, Span.
Derivation. From al t near, and lan, the edge of a river, Celtics in reference to its habitat:from the Hebrew, alon t an oak: or, according to others, from alitur amne , it thrives by theriver.