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Dicotyledons with Incomplete Flowers — Cupuliferce . 
Fruit-catkins resembling fruiting heads of Common Hop ( Humulus ), whence the name (Hop-Hornbeam). 
The minute aperture at the apex of the loose hollow involucral bracts, the margins of which are connate, permits the 
exposure of the stigma during the flowering stage. 
USES, &c.—The Hop-Hornbeam of Southern Europe (Ostrya carpinifolia) is a large spreading deciduous 
tree, occasionally planted in England. The wood of the American species is hard and very heavy. It is the Iron 
or Lever-wood of the United States. 
Natural Order 
BETULACEAl. Tab. 85. 
Diagnosis.— Trees with alternate 
leaves. F lowers 
amentaceous, unisexual, monoecious ; the pistillate flowers destitute of a 
perianth. Ovary 2-celled ; styles 2. Fruit a small 1-seeded nut. Seed 
exalbuminous. 
Distribution. —A small Natural Order, consisting of but two genera (Birch and Alder), confined to 
the cooler regions of the Northern Hemisphere. The two British species of Birch have each a wide 
range through Northern Europe, Asia, and North America, while Alder extends eastward into Asia. 
Number of British Genera, 2; Species, 3. 
Flowers of the staminate catkins in 3’s, with a minute perianth of 4 scales inclosing 4 stamens in Alder 
(Alnus); the’perianth reduced to a single scale subtending a pair of stamens in Birch ( Betula) : of the pistillate catkins 
in pairs, with 4 inner bracteole-scales and 1 outer bract-scale in Alder; in 3’s in the axil of a 3-lobed scale in Birch. 
Fruit-catkins with the bract-scales at length woody and persistent in Alder, deciduous in Birch. 
Nuts unappendaged in Alder; flat, and with lateral wings in Birch. 
