70 
SILVA OF NORTH AMERICA. 
BETULACE, 
of Europe and Asia, the American, European, and north Asian Alnus incana, the Himalayan Alnus 
Nepalensis' and Alnus nitida,’ and the American Alnus Oregona. 
In North America Alnus is injured by numerous insects,’ especially by those which bore into the 
living wood, but is comparatively free from the attacks of fungal diseases.’ 
the Willow and Poplar, growing sometimes under favorable condi- 
tions to the height of fifty or sixty feet, but at high elevations and 
in the extreme north often reduced to a low shrub ; it also inhabits 
northern Africa, Anatolia, Armenia, the Caucasian provinces, and 
Siberia. It has a symmetrical pyramidal or ultimately round-topped 
head, cuneate-obovate subrotund leaves obtuse or retuse at the 
apex, green on both surfaces, and glutinous while young, ovate 
strobiles, and nuts surrounded by a narrow coriaceous wing or 
wingless. 
The wood, which is probably not often distinguished commer- 
cially from that of Alnus incana, the second arborescent species of 
central and northern Europe, is soft, straight-grained, and light 
reddish brown ; soon decaying when exposed to changes of temper- 
ature and to alternations of moisture and dryness, it is practically 
indestructible as long as it is kept under water, and is therefore 
valuable for wharf and bridge piles, water pipes, and the barrels of 
pumps. It is also often employed in turnery and for carving, in 
the manufacture of basins, platters, wooden shoes, and light chairs, 
light packing-cases, and in cooperage. (See Industries of Russia, iii. 
338.) The durability of the small branches makes them valuable 
for lining drains. The wood, however, is most largely used in the 
production of charcoal for the manufacture of gunpowder, being 
surpassed for this purpose only by that of some species of Willow 
‘rangula, Linneus ; and in Europe it is extensively 
The bark 
and the fruit are used in tanning leather, and from the bark and 
and of Rhamnus 
planted in coppice, and regularly cut for this purpose. 
the foliage a yellow dye is obtained. Linen and woolen cloths are 
dyed black by boiling them with the flowers, young leaves, and 
branchlets. The European Alders are used to form hedges on 
low swampy ground, and are planted to hold the banks of streams 
with their strong stoloniferous roots. (See Loudon, Ard. Brit. iii. 
1681.) 
Alnus glutinosa has been introduced into the northern United 
States, where it is perfectly hardy, and while young grows very 
rapidly ; it suffers seriously, however, from borers working in the 
trunk and branches, and is usually short-lived. A number of vari- 
eties with variously cut or divided, or yellow leaves, or with fasti- 
giate branches, are propagated by nurserymen, and occasionally 
planted in the gardens of northern Europe (Dippel, Handb. Laub- 
holzk. ii. 160). 
1 D. Don, Prodr. Fl. Nepal. 58 (1825). — Wallich, Pl. As. Rar. ii. 
27, t. 131. — Regel, Nouv. Mém. Soc. Nat. Mosc. xiii. 141 (Mono- 
graphia Betulacearum) ; Bull. Soc. Nat. Mosc. xxxviii. pt. ii. 421 
(Gattungen Betula und Alnus) ; De Candolle Prodr. xvi. pt. ii. 
181.— Kurz, Forest Fl. Brit. Burm. ii. 476. — Hooker f. Fl. Brit. 
Ind. v. 600. 
Clethropsis Nepalensis, Spach, Ann. Sci. Nat. sér. 2, xv. 202 
(Revisio Betulacearum) (1841). 
Alnus Nepalensis, which is a tree fifty or sixty feet tall, with a 
straight trunk covered with thick compact smooth silvery bark 
tinged with purple or yellow, and broad rounded leaves, is common 
in the forests of the temperate Himalayas from southern Cashmere 
to upper Assam and Yu-nan. The bark is used in India for tan- 
ning and dyeing (Brandis, Forest Fl. Brit. Ind. 460.— Gamble, 
Man. Indian Timbers, 373). 
* Endlicher, Gen. Suppl. iv. pt. ii. 20 (1847).— Regel, Nouv. 
Mém. Soc. Nat. Mosc. l.c.; Bull. Soc. Nat. Mose. l.c. ; De Candolle 
Prodr. l. c. — Brandis, l. c. t. 57. — Hooker f. 1. e. 
Clethropsis nitida, Spach, I. c. (1841). — Decaisne, Jacquemont 
Voyage, 159, t. 159. 
Alnus nitida, which is probably the largest of the Alders, some- 
times rises to the height of a hundred feet, with a trunk five feet 
in diameter. It is acommon inhabitant of the northwestern Hima- 
layas and the Punjab, at elevations of between three and nine thou- 
sand feet above the level of the sea, fringing the banks of streams, 
The soft tough 
pale red wood is used in northwestern India in the manufacture of 
and occasionally following them into the plains. 
furniture and for the supports of rope bridges ; the twigs are em- 
The 
bark is used in tanning leather, in dyeing, and for making red ink 
(Gamble, J. c.). 
8 The insects which affect Alnus in North America have been 
little studied, although about fifty are now known. 
ployed in binding loads and in the construction of bridges. 
Lepidopterous 
borers like Fatua denudata, Harris, and Hepialus argenteomaculatus, 
Harris, appear to do the most damage to the stems of our Alders, 
the latter particularly affecting parts near the ground. Species of 
Saperda and other Longicorn beetles also injure the stems. 
Among foliage destroyers, a Flea-beetle, Haltica bimarginata, 
Say, is one of the most destructive known, and in some parts of the 
country the leaves of Alnus are eaten by the small dark-colored 
larve of this insect. Calligrapha scalaris, Leconte, also feeds upon 
the Alder in its larval and beetle stages. Saw-fly larve of several 
species are troublesome, either feeding externally or within the 
tissues of the leaves. Fenusa varipes, Norton, a small black Saw- 
fly, is sometimes very destructive to the leaves of Alders, the larve 
eating out the parenchyma, and causing them to turn brown and 
fall before midsummer, the successive broods destroying new leaves 
as they appear. The larve of a few of the larger Lepidoptera 
feed on the foliage, and Lepidopterous leaf-miners are common ; 
among these are several species of Lithocolletis and two or three 
of Gracilaria described as peculiar to Alnus. Lyonetia alniella, 
Chambers, makes large brownish blotch-mines in the leaves. 
Mites frequently form immense numbers of minute galls on the 
upper surface of the leaves ; and scale insects and aphids often 
seriously infest the trees. The so-called Alder Blight, Schizoneura 
tessellata, Fitch, sometimes occurs on the branches in large clusters 
covered with a white floccose secretion, and seriously affects the 
vitality of the plant. A species of Lepidopterous larva often lives 
within and destroys the staminate aments. 
* Of the many species of fungi found on Alnus in North Amer- 
ica, the greater number are common on this genus also in northern 
Europe. A mildew, Microsphera Alni, Winter, is common on the 
leaves of Alnus incana and Alnus rugosa, and Gnomoniella tubifor- 
mis, Saccardo, is frequently found, although rarely in its mature 
condition, on leaves of Alnus Alnobetula, where it forms discolored 
spots, from which small black spines, the necks of the perithe- 
cia, project. The common Pyrenomycetes Diatrypella Toccieana, 
De Notaris, and Melanconis Alni, Tulasne, frequently infest the 
branches of Alnus incana. Of Hymenomycetous fungi on Alnus 
may be mentioned, beside the common Tragia crispa, Fries, of 
Europe, a large form, Tragia Alni, Peck, peculiar to America, and 
Cyphella fulva, Berkeley & Ravenel, which appears in the form 
