BIRCH 
compressed, two-celled, crowned with two slender styles ; 
the ovule is solitary. 
The ripened pistillate ament is called a strobile and bears 
tiny winged nuts, packed in the protecting curve of each 
brown and woody scale. These nuts are pale chestnut brown, 
compressed, crowned by the persistent stigmas. The seed 
fills the cavity of the nut. The 
cotyledons are flat and fleshy. All 
the species are easily grown from 
seed, 
Michaux arranged the birches 
into two groups — one, including Rear View of a Staminate Scale and 
trees whose pistillate aments are ie oe Aaee iid 
ellow Birch, Betula Lutea ; 
sessile and erect: the Black, the Enlarged. 
Yellow and the Red; the other, 
those whose pistillate aments are stalked and pendulous: 
the Canoe, the White and the common Letwla alba of Europe. 
Remains of the group appear in the cretaceous rocks of 
Dakota, and during the tertiary period the genus existed 
throughout the northern central plateau of North America 
and at the same time abounded in Europe. 
WHITE BIRCH. GRAY BIRCH. ASPEN-LEAVED BIRCH 
Betula populifolia, 
Least common of the birches ; found on dry, gravelly, barren mar- 
gins of swamps and ponds. Short-lived, twenty to thirty feet high. 
Grows very rapidly. Ranges from Nova Scotia and lower St. Law- 
rence River southward mostly in the coast region to Delaware, and 
westward through northern New England and New York to southern 
shore of Lake Ontario. Leaves tremulous. 
Bark.—Chalky white or gray white, usually firm but easily sep- 
erable into thin plates; dark triangular markings scattered over the 
trunk and especially below the branches. At the base of large trees 
nearly black and broken irregularly by shallow fissures. Dranchlets 
at first reddish brown, closely dotted with round lenticels, then 
dark brown, and finally white near the trunk. Practically incor- 
ruptible. 
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