asa BIRCH FAMILY 



15-25 mm. long, 11-14 mm. in diameter, scales deeply 3-lobed, tomentose. 

 6-8 mm. long, lateral lobes ascending, samaras 6-7 mm. wide, nutlet twice 

 as wide as the wings : nigra, black. 



Along the bottom lands of streams and rivers, common along the 

 Mississippi bottoms as far as Wabasha County, also reported from near 

 Mankato. Distributed from Mass. to Minn., south to Fla., Tex. and Kan. 

 Blossoms in April and May, fruit ripe in autumn. 



The wood is light brown, close grained, hard, and strong, weight 36 

 lbs. It is used in manufacture of furniture, for staves and fuel. 



Betula Sandbergii B r i 1 1 o n 1904 



A tall shrub, 4-8 m. high, stems several from one root, ascending, 3-7 

 cm. in diameter, bark dark brown, not peeling, twigs dark gray or brown- 

 ish, with a few obscure lenticels, leaves ovate to oblong-ovate, rounded or 

 narrowed at the base, acutish at the apex, serrate, glabrous above, pubes- 

 cent beneath, at least along the veins, length 3-5 cm., width 1.5-3.5 cm., 

 petioles 6-10 mm. long, pubescent; leaves on sterile twigs more broadly- 

 ovate, larger, (7 cm. long, 5 cm. wide), coarsely serrate and more 

 pubescent; staminate catkins 1-2, at the ends of branches, 3-4 cm. long; 

 pistillate catkins pedicelled, cylindric, 12-15 mm. long, 1.5-2 mm. in di- 

 ameter; fruiting catkins ascending or erect, 15-20 mm. long, 6-7 mm. in 

 diameter, pedicels 8-12 mm. long, sometimes bearing a small leaf, scales 

 about 3.5-4 mm. lcng, margins ciliate, lateral lobes at right angles; samara 

 3 mm. wide, nutlet ovoid, about the width of the wing : Sandbergii, 

 named for J. H. Sand berg. 



In tamarack swamps, Hennepin County. This species has not been 

 collected in any other part of the state but probably occurs in tamarack 

 swamps in the northern part of the state. It is possible that it has been 

 confused with young trees of Betula papyrifera. Flowers in 

 May, fruits in September. 



Betula pumila Linne 1767 Dwarf Birch 



A shrub, 0.5-4 m. high, erect or ascending, twigs brown with light 

 dots, young shoots mostly soft-pubescent but not glandular, leaves obovate, 

 oval or nearly orbicular, wedge-shaped, narrowed or rounded at the base, 

 obtuse or rounded at the apex, somewhat coarsely serrate, dull green and 

 glabrous above in age, paler beneath, tomentose when young, becoming 

 glabrous in age, prominently reticulate-veined on both sides, 1-3.5 cm. 

 long, 8-20 mm. wide (larger on sterile shoots) ; staminate catkins borne 



