University of Vermont Extension
Department of Plant and Soil Science
Anytime News
Article
ALTERNATIVES TO BUCKTHORNS
Dr. Leonard Perry, Extension
Professor
University of Vermont
You should avoid planting buckthorn in
landscapes as birds spread their seeds to natural areas where they become
invasive. For this reason, some states
now prohibit their sale. There are many
good alternatives to plant instead of buckthorn, or to replace existing ones in
landscapes. These include American
hornbeam, witchhazel, black chokeberry, highbush blueberry, spicebush,
serviceberry, and viburnums.
The two primary introduced species of
buckthorn to avoid are the common (Rhamnus cathartica) and the glossy or
European (Frangula alnus, formerly Rhamnus frangula). These form large shrubs or small trees to 20
feet high or more, with a spreading and irregular habit. Twigs of the common buckthorn often have
spines on the tips. The leaves remain
dark glossy green late into the fall. Yellowish-green flowers in spring on
female plants near bases of leaf stalks are followed in fall by small black
fruits.
Most of the fruits fall below the
shrubs, forming a dense thicket that crowds out other plants. Birds and mice eat the fruit, which produces
a laxative effect furthering their distribution. Originally introduced into our country as an
ornamental shrub, for wildlife habitat, and for fence rows, these species now
are spreading to open fields as well as edges of forests and clearings.
Before removing any buckthorns from
natural areas, make sure it is one of these species. There are several native American buckthorns that
pose no problem. The Carolina buckthorn (R.
caroliniana) has finely toothed leaves like the
black cherry, and the alder buckthorn (R. alnifolia) is a low-growing
shrub to only three feet high.
The American hornbeam (Carpinus
caroliniana) also is called musclewood as the bark is sinewy as leg
muscles. Reaching about 20 to 30 feet
high, and about half that across, this hardy (USDA zone 3) native plant grows
well in sun or shade in moist soils. It
makes a dense, rounded tree with hanging clusters of fruit in summer, and
brilliant red leaves in fall in sun (yellow in shade). Place it well to begin with, as it doesn’t
transplant easily.
There are several nice witchhazels
to choose from, the hybrids often reliably hardy to warmer areas (USDA zone
6). The common witchhazel (Hamamelis
virginiana) is a native, upright shrub reaching 12 to 15 feet high, and
half that wide. It is hardy (USDA zone
4), and although grows more dense in sun also tolerates shade. It is attractive for its yellow flowers in
fall as the yellow leaves are falling.
If you want a small shrub, consider
the native black chokeberry (Aronia melanocarpa). Only reaching 4 to 5 feet high, it can spread
more. It is hardy (USDA zone 3), grows
in sun or part shade, and tolerates wet or dry sites. The white flower clusters in mid-spring are
followed by purplish-black fruit. Being
tart they are not favored by birds, but make nice jams. ‘Autumn Magic’ is a compact selection with
slightly larger fruits and good red fall color.
Highbush
blueberry (Vaccinium corymbosum) is a good native alternative to the
burning bush, not quite as tall but also with red fall color on several
selections. Its many burgundy, young
twiggy stems give it winter interest too. This plant of course has edible
berries for people and wildlife. Even
though it is self-pollinating, you may get more fruit from using at least two
selections. It can tolerate occasionally
wet soils.
There are many cultivars (cultivated
variety) available of the highbush blueberry, varying some
in hardiness and fall leaf color. Common
hardy ones with orange-tinted fall color are ‘Bluejay’ and the lower
‘Patriot’. Good choices for red fall
color are the hardy Friendship’, getting only 2 to 3 feet high and wide; ‘Tophat’,
getting only 1 to 2 feet high and 2 to 3 feet wide (hardy to USDA zone 5); and
the hardy ‘Toro’ (USDA zone 4), getting 4 to 6 feet high and wide.
Spicebush (Lindera benzoin) forms
a neat, spreading mound 6 to 10 feet high and slightly wider. The
stems smell spicy when crushed. This native plant adapts to wet or dry
soils,
and to sun or shade. Female plants have
scarlet berry-like fruit. Unfortunately,
it may only be hardy to warmer areas (USDA zone 5).
There are several native species of
serviceberry that form large shrubs, or multi-stem small trees. The Allegheny serviceberry (Amelanchier
laevis) is perhaps the most commonly found in our area. Reaching 15 to 25 feet high, and half that
wide, it has an upright and open habit.
It grows well in sun or shade, and is quite hardy (USDA zone 3). The attractive white spring flowers are
followed by edible black fruits, then in fall by attractive red to orange
leaves.
There
are several native viburnums you could use as alternatives to
buckthorns, but keep in mind species have varying susceptibility to a
new
pest, the Viburnum leaf beetle. Witherod
(V. cassinoides) is less susceptible, reaching 8 to 10 feet high and
wide. White flowers lead to fruit that
start green, then change to red before black.
The orange-red fall leaves are attractive. Witherod is quite hardy in wide-ranging light
and soil conditions.
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