=3.= =Betula papyrífera= Marshall. Paper or Canoe Birch. Plate 34.
Rather a small tree; bark thin, creamy white; chalky, dark near the base
on old trees, separating in thin papery layers; shoots green, glandular
and hairy, becoming glabrous and reddish-brown; leaves ovate or
rhombic-ovate, acute to long taper-pointed, truncate, rounded or
wedge-shape at the base, average blades 5-8 cm. long, usually
irregularly double-serrate, hairy at first, becoming glabrous above or
nearly so, remaining more or less pubescent below, especially on the
veins and with tufts of hairs in the axils of the veins, minutely
glandular on both surfaces, sometimes with only a few glands on the
midribs above; fertile catkins 2-4 cm. long and about 6-9 mm. wide,
bracts about 4 mm. long, pubescent on both faces, lobed to about
one-third the distance from the apex, the lateral lobes the largest,
divaricate or slightly recurved; seed deeply notched at apex, nut oval,
pubescent at the apex, wings as broad as, or broader than the nut.
=Distribution.=--Alaska to Labrador, south to New York, northern
Indiana, Colorado and Washington. In Indiana it has been reported from
Lake, Laporte, Marshall and St. Joseph Counties. It has not been found
as a native in Ohio. This species is another example of a northern form
finding its southern limit near Lake Michigan.
=Remarks.=--This species in other parts of the country is known as
white, paper and canoe birch. I have not seen specimens more than 2 dm.
in diameter in Indiana.
=4.= =Betula nìgra= Linnæus. Black or Red Birch. Plate 35. A medium
sized tree; bark on young trees peeling off transversely in thin
reddish-brown strips which roll back and usually persist for several
years, bark of older trees dark brown, furrowed and separating into
short plates or peeling off in strips; young twigs hairy, becoming
glabrous and reddish at the end of the season; leaves rhombic-ovate,
acute, short and broadly wedge-shaped at the base, blades of ordinary
leaves 4-8 cm. long, irregularly toothed, glabrous above and pubescent
beneath, rarely entirely glabrous; fertile catkins generally 2-3 cm.
long, and usually slightly less than 1 cm. wide; bracts 6-10 mm. long,
pubescent, ciliate, lobed to near the middle, the lobes about equal;
nuts broadly ovate, broader than its wings, pubescent at the apex; wood
light, strong, close-grained, heart wood light brown.
=Distribution.=--Massachusetts west to Minnesota and south to Florida
and Texas. In Indiana it is found more or less frequent in the counties
bordering the Kankakee River, and as far east as St. Joseph, Marshall
and Miami Counties. Along the Kankakee River it is frequently a tree of
6-8 dm. in diameter. This species has not been found in Michigan,
northeastern Indiana or northern Ohio. It has never been noted near Lake
Michigan, and the nearest point is Cedar Lake in Lake County about 20
miles south of the Lake. It is more or less frequent along certain
streams throughout the southwestern part of the State. It is found as
far north as Putnam and Marion Counties and eastward as far as
Bartholomew, Scott and Clark Counties. There are no records for this
species for eastern Indiana or western Ohio. About Hovey Lake in Posey
County it reaches its greatest size, where trees up to 8 dm. in diameter
and 30 m. high are to be found. In the "flats" in certain parts of
Jackson and Scott Counties it becomes a common tree, associated with pin
oak and sweet gum.
[Illustration: Plate 35.