Plant of the Week
Sourwood
Latin: Oxydendrum arboreum
Larry McMurtry, best selling author of Lonesome Dove
and a score of other books, analogizes the nation’s interstate highway system to
rivers. From either a flatboat on the Missouri or a car window on "the 40," you
are a spectator to the activities of mankind and the nature which surrounds us,
not a participant.
From a biologist’s perspective, the change of vegetation along a river is
slow, only altering as the grip of winter forces more hardy species to establish
themselves along its banks. But our interstates bisect the landscape and changes
come more rapidly. Thus, it is only a short trip along I-40 east of Memphis when
we first encounter sourwood, Oxydendrum arboreum, in its native range.
Sourwood, the largest tree in azalea family in North America, ranges from the
southern tip of Illinois to the gulf coast in Louisiana to Florida. It does not
occur wild in Arkansas, but it will grow here. Trees have a pyramidal profile
when grown in the open and reach 30 feet tall in landscapes. They can reach
twice that height in the wild. It occurs in the forest as an occasional tree,
not as dense stands.
The tree has leaves identical to the shape of azalea leaves, but they may be
6 inches long. The leaves are a rich glossy green in the summer with mature
trees displaying the most beautiful fall color in our southern landscape. If
sourwoods were as numerous in our forests as are maples in the New England
landscape, travelers would visit us in the fall instead of trekking north.
Flowers are another significant attribute of this beautiful tree. In
mid-spring after the leaves have appeared, pendant panicles of small urn shaped
white flowers are produced at the ends of branches. The flowers give rise to one
of the plant’s common names - "Lily of the Valley Tree." In areas where the
trees grow wild, they are a favorite bee tree for those tending the hive.
Donald Peattie is one of the most lyrical writers I know of when it comes to
describing trees. In his 1966 reissue of A Natural History of Trees, he
states: "One buys sourwood honey as one buys any such rare product from
its producers - not in a commercial spirit, paying for it and carrying away the
wares - but with all the due ceremony observed between a collector and a
creative artist." His description of the dance that occurs between the farmer’s
wife and the prospective buyer is a poetic rendition of mid-century American
life which we will never see again.
Sourwood gets its name from the sour taste of the leaves and branches of the
tree. They have a taste similar to that of oxalis leaves with the distinctive
sharpness of oxalic acid. In past times, the leaves were brewed for herbal cures
of various internal ailments.
As a member of the azalea family, sourwood grows best in acidic, well drained
sites. In its native range, it’s often found on sandy, acidic sites. It’s not
well suited for heavy clay soils. As a young tree, it grows irregularly and
often fails to have a typical upright habit until well established.
Like all members of the azalea family it has fine, shallow roots and is
sensitive to too much or too little water.
By: Gerald Klingaman, retired
Extension Horticulturist
- Ornamentals
Extension News -
September 7, 2001
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