Crooked Run Valley
sweet birch (Betula lenta)
Betula lenta var. genuina Regel
The genus name is classical Latin for birch. The specific epithet lenta means
flexible or tough referring to the twigs.
CONFIRMATION STATUS: Confirmed.
TAXONOMY: The currently accepted scientific name for sweet birch is
Betula lenta L.
Sweet birch is frequently confused with yellow birch (Betula alleghaniensis),
but can be distinguished by its fine-toothed leaves with scalloped or heart-
shaped bases and by the non-peeling blackish-red bark.
NATIVE STATUS: Native, United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS: Sweet birch is a med-
ium-sized tree attaining heights of 50 to 60 feet with diameters of 18 to 24
inches and a long clear single straight trunk. It grows best in the ancient
forest loam and can almost always be found near mountain streams at the
head of coves. The tree can also be found on rocky, boulder strewn sites
with poor soil, where it is apt to be shrubby and have a stunted appearance.
The numerous branches spread out from the stem at a wide angle. The
twigs and smaller branches droop at the ends. Twigs are slender, reddish
brown and lenticellate with a wintergreen smell when cut. On older trees,
spur shoots are apparent. Terminal buds are absent, lateral buds two
toned, green and brown. The bark is reddish brown to black on young
trees, later gray to nearly black, eventually breaking up into large, thin,
irregular, scaly plates (the bark also has a winergreen smell). Leaves are
alternate, simple, pinnately-veined, ovate, with an acute tip and cordate
base. Leaves have single or irregularly double, sharply serrate margins, 2
to 4 inches long, with a stout and pubescent petiole. Leaves are shiny dark
green above, paler below. Flowers are monoecious, preformed, green male
catkins near the end of the twig, 3/4 to 1 inch long; females are upright,
1/2 to 3/4 inch long, green tinged in red, appear or elongate (males) in mid-
spring.The cone-like aggregate, brown, 1 to 1 1/2 inches long, scales hair-
less or nearly so, containing very small 2-winged nutlets, ripen and break
apart in late summer and fall. The roots are deep and wide spreading.
REGENERATION PROCESSES: Betula lenta propogates itself by re-
seeding. Seed fall is during mid-September through November. Seed
dispersal is normally by wind and seeds may be blown some distance over
crusted snow. Nothing is known about quantities of seeds produced or how
far they are spread. Seed production begins when trees are about 40 years
old; large seed crops are produced every 1 or 2 years.
Under forest conditions, seeds normally germinate during the spring after
they are dispersed. Germination may extend over 4 to 6 weeks. Germina-
tion is delayed when the embryo is dormant. Moist mineral soils, rotten
logs, and humus are suitable germination media.
Vegetative reproduction has also been observed for sweet birch. Sweet
birch has been known to reproduce well from small stumps but seems to
be less prolific than many of its associates maple, sugar maple, beech
(Fagus grandifolia), yellow-poplar, and northern red oak.
SITE CHARACTERISTICS: Sweet birch grows best on deep, rich, moist,
acidic, well-drained soils; however, it is also found on a variety of less favor-
able sites with rocky coarse-textured or shallow soils. It primarily on three
soil orders: Spodosols, Inceptisols, and Ultisols. Because it is occasionally
abundant on rocky mountains in Pennsylvania, sweet birch may be valu-
able for soil protection. On other poor soils, however, such as the exces-
sively dry portions of the Harvard Forest in Massachusetts, sweet birch
is partially or completely replaced by oaks and conifers. Betula lenta grows
best in full sun, but will tolerate light shade.
Precipitation in the range of sweet birch averages about 1140 mm (45 in) a
year, about half of it falling during the growing season. In the northern part
of the range, snowfall averages 200 to 250 cm (80 to 100 in) a year. Aver-
age annual temperature is about 7° C (45° F) in the north and about 13° C
(56° F) in the southern Appalachians. The July average is 21° C (70° F) in
New England and 23° C (74° F) in the southern Appalachians. Mean Janu-
ary temperatures are -9° to -7° C (15° to 20° F) in New England and -1° to
4° C (30° to 40° F) in the southern Appalachians. The growing season var-
ies from 90 to 220 days, depending on latitude and elevation.
Sweet birch grows over a wide range of altitudes from near sea level
along the New England coast to an upper extreme of 1220 to 1370 m
(4,000 to 4,500 ft) in the southern Appalachian Mountains. In New Eng-
land, the species is fairly common in southern Maine, the highlands of
New Hampshire, western Vermont, the highlands of Massachusetts
and Rhode Island, and throughout Connecticut. In the southern Appala-
chians, where sweet birch grows best, the optimum elevation is between
610 and 1370 m (2,000 and 4,500 ft). Moist, protected north-erly or
easterly slopes are considered most favorable for sweet birch in both
northern and southern parts of its range.
SUCCESSIONAL STATUS: Sweet birch is a common (occassionally a
dominant species) in middle to later stages of successional growth. How-
ever, early successional stages, particularly in open or recently clear-cut
situations, are not conducive to dominant growth. Instead, sweet birch
seedlings develop best during their early years when protected by side
shade or light overhead shade. Scattered individuals frequently grow as
advance reproduction in openings in mature stands or under younger
stands of light to moderate crown density. Sweet birch is also sometimes
present in advanced hardwood growth.
SEASONAL DEVELOPMENT: Flowers open in April and May. Seeds
ripen from about mid-August through mid-September.
GENERAL DISTRIBUTION: Sweet birch is primarily a tree of the
northeastern United States. It grows from southern Maine westward in
southern Quebec, New Hampshire, Vermont, New York, and southeastern
Ontario to eastern Ohio; and south in Pennsylvania through the Appala-
chian Mountains to northern Alabama and Georgia. Forest survey data
indicate that sweet birch is most abundant in Massachusetts, Connecticut,
New York, and Pennsylvania.
SKY MEADOWS DISTRIBUTION:
Tree specimens can be found on trails marked in red.
Appalachian Trail/Old Trail
South Ridge/North Ridge
Rolling Meadows/ Lost Mountain
HABITAT TYPES AND PLANT COMMUNITIES: Rich, moist, cool
forests, especially on protected slopes, to rockier, more exposed sites.
Sweet birch seldom grows in pure stands and is found scattered amongst a
variety of other species.
Important associated tree species include yellow- poplar (Liriodendron
tulipifera), basswood (Tilia spp.), white ash (Fraxinus americana), sugar
maple (Acer saccharum), red maple (Acer rubrum), northern red oak
(Quercus rubra), white birch (Betula papyrifera), gray birch (Betula
populifolia), hemlock (Tsuga spp.), and eastern white pine (Pinus strobus).
Understory vegetation varies with locality, but commonly associated
shrubs are mountain maple (Acer spicatum), striped maple (Acer
pensylvanicum), flowering dogwood (Cornus florida), downy service-
berry (Amelanchier arborea), American hornbeam (Carpinus caroliniana),
and eastern hophornbeam (Ostrya virginiana). Associated herbaceous veg-
etation includes Solomons-seal (Polygonatum pubescens), marsh blue
violet (Viola cucullata), clubmosses (Lycopodium spp.), mayapple (Podo-
phyllum peltatum), trilliums (Trillium spp.), jack-in-the-pulpit (Arisaema
atrorubens), and a variety of ferns. In former clearcut areas where young
stands are established, blackberry (Rubus spp.) is abundant.
IMPORTANCE AND USES: Betula spp. (including the leaves of Betula
lenta) are used as food plants by the larvae and caterpillars of a large num-
ber of Lepidoptera species, including leaf-miner species (Bucculatricidae),
case-bearer species (Coleophoridae), Notodontidae species such as
Leucodonta bicoloria (white prominent). Many moths from Families
Geometridae (geometer moths), Lymantriidae (tussock moths), and
Sphingidae (sphinx moths) (among others) frequent selected species of
Native Americans used Betula lenta medicinally to treat dysentery, colds,
diarrhea, fevers, soreness, and milky urine, and as a spring tonic.
Betula lenta was used commercially in the past for production of oil of
wintergreen (methyl salicylate) before modern industrial synthesis; the
tree's name reflects this scent of the shoots.
The sap flows about a month later than maple sap, and much faster. The
trees can be tapped in a similar fashion, but must be gathered about three
times more often. Birch sap can be boiled the same as maple sap, but its
syrup is stronger (like molasses).