Black Walnuts (Juglans nigra) are beautiful,
valuable deciduous trees with one defect - they can be hard
to live with if you're a sensitive plant, and their nuts can
irritate your mouth if you have a sensitive mouth.
The word "walnut" derives from "wealhhnutu"
(Old English), which means "foreign nut", because
it was introduced from Gaul and Italy.
Growing
conditions
Walnuts are somewhat
picky, and don't like sites with insufficient moisture, too
much moisture, steep slopes, or hard pans and shallow soils
with bedrock or gravel that restrict root growth. Ideally, they
prefer well-drained, loamy soils with a balanced pH, on a smooth
or gently rolling site.
Uses
Heartwood is heavy, hard, strong, and
durable, with a warm, chocolatey brown color much prized by
furniture manufacturers and many other industries.
Walnuts are delicious and an excellent
source of important nutrients.
Fun
Facts
An allelopathic substance (chemicals produced
by the tree to discourage competition) called juglone exudes
from all parts of the walnut tree, which can .affect other
plants either through root contact, leakage or decay in the
soil, falling and decaying leaves, or when rain leaches and
drips juglone onto plants below.
Tall fescue and Kentucky bluegrass grow
well near black walnut except during drought conditions when
soil moisture is low.
Size
Grows to 30-130
feet.
Form & Shape
Generally full and round.
Bark
Thick
bark is dark brown and divided by deep fissures into rounded
ridges, with a chocolate brown under-color when broken off the
tree.
Leaves
Has pinnate (compound)
leaves 1-2' long, with an odd number -- usually from 7 to 23
-- of small yellowish green leaflets 3-5" long leaflets,
spaced alternately along the branches.
Flowers
Walnuts are monoecious, with
male flowers borne in long, unbranched, drooping catkins and
female flowers borne singly or in short spikes.
Fruit
Walnuts are borne singly or
in pairs, enclosed in a solid, non-splitting green husk. The
edible, oil-rich nut kernel is encased in a thick, hard, ridged,
black shell.
Below is a schematic map of the Ladd Arboretum,
with a dot in red showing where the Nut Trees (including Walnut)
are located. Click to take a virtual tour
of the Ladd.
