Crooked Run Valley
American basswood (Tilia americana)
Tilia americana var. neglecta (Spach.) Fosberg
Tilia relicta Laughlin
CONFIRMATION STATUS: Confirmed.
TAXONOMY: The currently accepted scientific name for basswood
is Tilia americana L. Some authorities agree that Tilia americana, Tilia
heterophylla (white basswood), and Tilia caroliniana (Carolina basswood)
are more correctly treated as one highly variable species.
NATIVE STATUS: Native, United States. Native and introduced,
GENERAL BOTANICAL CHARACTERISTICS: Basswood is a native
deciduous tree. Mature heights range from 75 to 130 feet (23-40 m) with
diameter ranges from 36 to 48 inches (91-122 cm). The bark of mature
trees is up to 1 inch (2.54 cm) thick at the base of the trunk. The bark is
furrowed into narrow, flat-topped, firm ridges with characteristic horizontal
cracks; young trees have smooth, thin bark. The inflorescence is a drooping
axillary cyme. The fruit is dry, hard, does not open at maturity, subglobose
to short-oblong, and is usually 0.2 to 0.28 inch (5-7 mm) in diameter, and
bears one or two seeds. The root system of basswood is composed largely
of lateral roots; it does not usually form a taproot. Basswood root depths
are usually shallow relative to associated species root depths. In prairie
soils bur oak (Quercus macrocarpa), shellbark hickory (Carya lacinosa),
and northern red oak all have deeper roots than does basswood. Maximum
root depth in basswood averages 1.2 feet (36.5 cm) the first year, and 5 to
6 feet (1.5-1.8 m) by the third year; roots are not well developed below
approximately 2 feet (61 cm). On prairie soils the deepest roots of a 28-
year-old basswood were 27 feet (8.2 m) but most of the roots were in the
top 4 to 5 feet (1.2-1.5 m) of soil. Adventitious roots will develop as the
stem is buried. The tree crown is usually broad and rounded, but in close
stands is more columnar. The branches are small, weak, and often
pendulous. Maximum longevity is approximately 200 years.
REGENERATION PROCESSES: The youngest recorded age at which
basswood first reproduces is 15 years. Basswood flowers are insect
pollinated, mostly by bees and flies. Basswood produces good quantities
of seed at 1- to 3-year intervals. The relatively heavy fruits are not usually
carried long distances by the wind. Seeds can remain dormant for up to 3
years. This deep dormancy is thought to be caused by an impermeable
seedcoat, dormant embryo, and tough fruit wall. Shade enhances
establishment and initial survival, but heavy shade limits subsequent
growth and development. Seedlings can establish in as little as 25 percent
of full sunlight. The higher soil temperatures in forest openings are better
suited for good seedling growth, but seedlings are sensitive to soil nutrient
deficiencies which may render them less tolerant to shade than older trees.
However, dense reproduction is only obtained under partial canopies. Most
basswood reproduction originates as stump sprouts. Almost all basswood
trees 4 inches (10 cm) or less d.b.h. will sprout from the stump, and more
than 50 percent of sawlog-size trees will sprout as well. Sprouts have been
obtained from basswood trees over 100 years old.
SITE CHARACTERISTICS: Basswood is characteristically found in rich
uplands on mid-slopes in mixed deciduous forests. It is sometimes found in
swamps. Basswood is generally confined to sandy loams, loams, or silt loams,
and achieves its best growth on the finer textured soils. Best growth is on
moist sites, but basswood will also grow on coarse soils that are well
drained. Basswood is moderately tolerant of flooding; it occurs on floodplain
sites that have probabilities of annual flooding between 50 and 100 percent.
Acceptable soil pH ranges from 4.5 to 7.5, though basswood occurs most
often on less acidic to slightly basic soils. Because basswood is nitrogen
demanding it grows poorly on nitrogen deficient soils. At the western limits
of its range, basswood usually grows on the eastern side of lakes and along
major drainages where it is naturally protected from fire. The maximum
elevation at which basswood is found is 4,930 feet (1500 m) in the southern
SUCCESSIONAL STATUS: Basswood is moderately tolerant of shade.
It achieves its highest densities in sugar maple-basswood stands that are
late successional to climax forests. Sugar maple-basswood can eventually
replace oak-hickory on favorable upland sites in the upper Midwest.
Succession of oak-hickory to sugar maple-basswood can be accelerated
where harvesting or other disturbance releases the tolerant understory
species. The persistence of the moderately shade tolerant basswood in
stands containing highly shade tolerant sugar maple is dependent on their
differing modes of reproduction. Sugar maple produces large numbers of
seedlings which are positively correlated with the occurrence of basswood
in the canopy. Stump sprouting allows basswood to maintain itself in a stand
with the more shade-tolerant sugar maple; basswood stump sprouts can
reach canopy size faster than the more numerous maple seedlings. Patchy
or large scale disturbance may favor basswood because of its sprouting
ability and presence in the understory.
SEASONAL DEVELOPMENT: Basswood usually flowers in June, but
flowering dates range from late May to early July. Flowering occurs from
1 to 4 weeks after spring leaf-out. In Minnesota, bud swell occurs in from
late April to early May, and leafing out occurs from early to mid-May.
Seeds are dispersed in October, and leaf fall occurs from September to
GENERAL DISTRIBUTION: The native range of basswood extends
from southwestern New Brunswick and Maine west to southern Quebec,
southern and western Ontario, Michigan, Minnesota, and southeastern
Manitoba; south to eastern North Dakota, northern and eastern Nebraska,
eastern Kansas, and northeastern Oklahoma; east to northern Arkansas,
Tennessee, western North Carolina, and New Jersey.
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: Basswood
generally occurs in mixed stands and rarely forms pure stands. It is
codominant in the sugar maple (Acer saccharum) -basswood cover type,
and is a common component of many other mesophytic forests.
Associates in the sugar maple-basswood type include white ash (Fraxinus
americana), northern red oak (Quercus rubra), eastern hophornbeam
(Ostrya americana), red maple (Acer rubrum), and American elm (Ulmus
americana). To the east, eastern hemlock (Tsuga canadensis) may be
present, and communities on mesic sites would be more like to include
sugar maple, yellow birch (Betula alleghaniensis), eastern hemlock, and
IMPORTANCE AND USES: Basswood is preferred browse for white-
tailed deer. Basswood flowers are visited by honeybees for nectar. The
easily decayed wood produces a disproportionate number of cavities which
are used by cavity-nesting animals including wood ducks, pileated
woodpeckers, other birds, and small mammals.
Basswood is of limited use in mixed hardwood plantings on disturbed
sites in Ohio.
Basswood wood is soft and light; it is valued for hand carving and has many
other uses including cooperage, boxes, veneer, excelsior, and pulp. Basswood
is economically important for timber, especially in the Great Lakes States.
Basswood is planted as a shade tree or ornamental. The fibrous inner bark
("bast") has been used as a source of fiber for rope, mats, fish nets, and woven baskets.