BIRCH 



compressed, two-celled, crowned with two slender styles ; 

 the ovnie is solitary. 



The ripened pistillate anient 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 

 liUs 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 gi'oups — one, including 

 trees whose pistillate ameiits are 

 sessile and erect : the Black, the 

 Yellow and the Red ; the other, 



those whose pistillate aments are stalked and pendulous : 

 the Canoe, the White and the common Bctula 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. 



Rear View of a Staminale Scale and 

 Front View of a Pistillate Scale 

 of Yellow Birch, Belula Lulea ; 

 Enlarged. 



WHITE BIRCH. GRAY BIRCH. ASPEN-LEAVED BIRCH 



Bt'tula po^ii/ifolia. 



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 lielow the branches. At the base of large trees 

 nearly black and broken irregularly by shallow fissures. Branchlets 

 at first reddish brown, closely dotted with round lenticcls, then 

 dark brown, and finally white near the trunk. Practically incor- 

 ruptible. 



297 



