AR Gardener Magazine
Articles
Cladrastis kentukea, Yellowwood
In the garden we constantly make choices and compromises.
Because most of us have finite space to work with we become jealously attached
to any voids lest we squander it on some undeserving interloper. The criteria
used to select the perfect plant to fill these spaces are as many as there are
gardeners. The popularity of Bradford pears shows that most opt for the big,
easy show. Others are more discerning and want something different, yet with a
grace and beauty worthy of our precious space. Yellowwood, Cladrastis
kentukea, is one to consider for these valued areas.
Yellowwood is a native deciduous trees that can reach 40 feet in
height, usually with multiple trunks ascending from low on the trunk, giving the
tree an oval form. It appears in scattered locations throughout the eastern
woodlands, probably in its greatest concentration in the southern Appalachians.
It’s native range is far flung with it occurring as far north as central Indiana
and Illinois and west into Oklahoma and south to Georgia. Nowhere is it common
but when found in the wild it is usually associated with limestone bluffs or
river valleys draining calcareous formations. In Arkansas it is fairly easy to
find along the Buffalo River.
As a member of the legume family, yellowwood shares family
traits of flowers, fruit and leaf, but not the ability to fix its own nitrogen
from the atmosphere. It has odd-pinnately compound leaves with 5 to 9 leaflets.
The leaves are big, to 10 inches long with leaflets entire, ovate in outline and
to 4 inches long. The bright green leaves of summer turn to clear yellow or gold
in the fall and stand out effectively in the landscape because of their texture
and hue.
The pea-flowers of yellowwood are white, fragrant and to one
inch long and borne on long, pendant panicles that can reach a foot in length.
Blooms appear after the leaves in early May and, in a good year, cover the tree.
Unfortunately yellowwood tends to be alternate-year flowering plus slow to
flower when grown from seed. Mike Dirr reports a 17 year old tree he grew from
seed which had not yet flowered. Generally trees must be 15 to 20 feet tall
before they produce their first bloom. The dangling seed pods are tanish-gray in
color and have little impact on its winter form.
Yellowwood got its common name when the botanist who discovered
it chopped down several trees to gather seeds. The botanist in question was the
widely traveled French plant explorer André Michaux, who collected during the
tumultuous period following the French Revolution and the rise of Napoleon I.
The year was 1796 near Fort Blanc along the Cumberland River in east Tennessee.
During a raging blizzard Michaux spotted the tree as something new, even though
it was leafless at the time, because of its short, multi-trunked stature and
smooth, gray bark.
Michaux suggested to the territorial governor that the heartwood
could be used as a yellow dye. Because of this recommendation and before the
invention of manufactured dyes in the late 19th century many a homespun was dyed
using wood chips from the tree. Michaux never had the opportunity to officially
name the tree because wanderlust was deep in the marrow of his bones. After a
short stint back in France he traveled to Madagascar where he died of fever in
1803.
His son Francois named the tree Virgilia lutea in 1812
using material collected by his father. The German taxonomist Karl Koch
reclassified it in 1869 as C. lutea. In recent years its official name
was again changed to C. kentukea as a kind of globalization of plant
names occurs amongst the taxonomists who attempt to precisely follow the rules
of prior publication, regardless of the suitability of the old name.
Yellowwood is not a tree for the impatient gardener. Like a fine
wine, this tree needs time to achieve its very best. Like almost all trees, it
grows best in full sun in a fertile, well drained soil. It is considered a
medium growth rate tree, producing 12 inches of new growth on average once
established. It will tolerate high shade and poorer soils, but growth will be
slower. Even though it is often found associated with calcareous sites, another
characteristic of the legumes, it appears to grow about as well on acidic soils
as alkaline. The tree is pretty much unbothered by disease or insect pests and
usually lives 50 to 75 years as a landscape specimen.
The nursery trade grows this species from seed and in modest numbers at best.
It may take some hunting to find a nursery that offers it, but all gardeners
know that the hunt is half of the fun.
This story first appeared in the
AR
Gardener Magazine.
By: Gerald Klingaman, retired
Extension Horticulturist - Ornamentals
Tree Profile - May 2002
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