The Seed is the horticultural magazine of the Nebraska Statewide Arboretum. This issue was written by Jim Locklear. Copyright 1998. For a full version of this publication with photographs, call 402-472-2971.
The Seed, Spring 1998
Landscaping Nebraska Style
THE CHALLENGE
The environment of Nebraska presents many
challenges to those wanting to beautify the landscapes of their homes,
businesses and communities. Extremes of heat and cold, large fluctuations
in temperature, periodic drought, difficult soils - the list could go
on and on.
But the biggest challenge may be mental,
not environmental. We may approach gardening and landscaping with certain
notions and ideas that make the task harder than it really needs to be;
and that may cause us to overlook approaches that make the best sense,
both environmentally and aesthetically.
Imagine for a minute your ideal landscape.
Conjure up the image in your mind. Chances are that for most gardeners
it will be a replica of something seen "back east." Much of
what we have tried to do in our gardens, yards and public landscapes in
Nebraska is to reflect the horticultural practices and traditions of the
eastern United States, traditions that, historically and culturally, have
their origins in Europe.
While there is nothing inherently wrong
with these practices and traditions, there are two main reasons for questioning
their imitation in Nebraska. The first is practical. Eastern landscape
mainstays like hollies, rhododendrons and boxwood are wonderful plants,
but they can require serious horticultural effort to grow in Nebraska
(and even then may just barely survive). Many of the important ornamental
plants used in the east just do not do well in our climate and soils,
despite our best efforts to coddle them with extra water and care.
The second reason is a philosophical one.
Nebraska is not Virginia or Indiana or even Missouri. The natural landscape
is quite different, as are the plants that comprise that landscape. Instead
of trying to imitate other places and import other traditions and styles,
why not celebrate the intrinsic beauty of Nebraska in our cultivated landscapes?
Why not develop a "Nebraska Style" of landscaping?
LOOKING TO THE LAND
We can start to develop this Nebraska
Style by taking time to consider where we live. To look to the natural
landscape of Nebraska for ideas and inspiration. To discover the "genius"
of the place.
In a very general sense, Nebraska has three
basic plant communities - the eastern woodlands, the Panhandle pinelands
and the prairies in between. Each has its own unique assemblage of plants,
and each has its own distinctive character or "feel." A Nebraska
Style of landscaping would reflect one or more of these natural settings
in the cultivated landscapes of our homes, businesses and communities.
The most obvious way to do this is through
the use of native plants - those that grow naturally in a given area.
A list of the important native plants for each of these three plant communities
is presented in this issue of The Seed.
Some people are purists when it comes to
"natural" landscaping and use nothing but native plants. However,
native plants are not always easy to obtain. Therefore, sometimes out
of necessity, others try to achieve the same effect using non-native plants
similar in appearance and cultural requirements to natives. For example,
rugosa rose (Rosa rugosa), a native of Asia, might be a substitute for
the native prairie rose (Rosa arkansana). Both are similar in appearance
and hardiness and both produce a similar effect in the landscape. However,
while the rugosa rose is widely available, the prairie rose cannot be
found in the nursery trade.
The other way to reflect a sense of place
in our cultivated landscapes is to mirror the patterns that are found
in natural places. Every landscape has its own unique textures and tones,
rhythm and stride which can be replicated to an extent through the selection
and placement of plant material. Once seen and comprehended, these patterns
can become a guiding force in creating landscapes that reflect a sense
of the natural.
To develop a Nebraska Style of landscaping,
we need to take a closer look at the three basic plant communities of
the state.
THE EASTERN WOODLANDS
Cloaking the hills and bluffs of the Missouri
River, and trailing westward along its tributaries, is a forest dominated
by oaks and supported by a cast of other large trees. The heart of this
plant community, technically known as the eastern deciduous forest, lies
to the east and south, in the Ozarks of Missouri and Arkansas. The stands
of this forest along the Big Muddy in Nebraska, at places such as Indian
Cave State Park, represent the western fringes of its distribution in
the United States.
Tall, canopy-forming trees form the backbone
of this plant community. Depending on the exposure and slope of the site,
the dominant tree is usually bur oak, with green ash, hackberry, elm and
walnut also in attendance. On moister sites, red oak and linden provide
the shade. Other trees such as white ash, bitternut and shagbark hickory,
and oaks like chestnut, white, and black oak also can be found in the
forests of southeast Nebraska, although they are much less common. These
trees are all deciduous, meaning they lose their leaves in the winter.
With these big trees jostling for space
in the canopy, smaller trees and other plants must live either in the
shade or at the edge of the forest. So it is that the eastern woodlands
have another suite of trees that occupies the space between the canopy
and the ground - the understory trees.
The eastern woodlands in Nebraska include
a number of smaller-statured trees. Many bloom in the spring, producing
their flowers before the larger trees leaf-out and intercept most of the
sunlight. These understory trees include redbud, serviceberry and hawthorn.
Ironwood is another important understory tree, although its fruit is showier
than its flowers.
These trees also can occur at the edges
of the forest, creating a transition zone between prairies and pastures
and the main body of the forest. They are often accompanied by an array
of shrubs such as rough-leafed dogwood, coralberry, hazelnut and sumacs.
Below the understory is a third layer of
vegetation. This is the ground layer, and is comprised primarily of shade-tolerant
wildflowers. Many of these plants are spring blooming ephemerals that
flower early and go dormant as the canopy leafs out. A few shrubs, such
as gooseberry and coralberry, also can tolerate the deep shade at the
ground layer.
DESIGN IMPLICATIONS
While this plant community occupies only
a narrow zone along Nebraska's Eastern Shore, it is the one we most often
try to imitate, consciously or unconsciously, in our cultivated surroundings.
It is a landscape that most people find comforting, perhaps because we
like the sense of enclosure provided by the trees, or because this is
the environment out of which many Nebraska settlers, both past and present,
came as they made their way west.
All landscape plantings change and mature.
As trees increase in size, so does the amount of shade in the landscape.
If you are faced with this situation, take it as an opportunity to develop
your own interpretation of Nebraska's eastern woodlands.
1. Notice the natural layering of vegetation in the forest, and then begin
to think vertically about the cultivated landscape. Be concerned not only
with big shade trees, but enhance the entire landscape by working in understory
trees, shrubs and ground layer plantings.
2. The eastern woodlands are not a place of riotous colors, even in the
full glory of autumn. Learn to be content with greens. The dominant trees
such as oaks, ash and linden have more muted, understated fall colors.
Use scatterings of sumac, rough-leaf dogwood or wahoo to bring accents
of red and orange into the fall landscape.
3. Bring spring and summer color into the landscape through the use of
smaller, ornamental trees such as redbuds, serviceberry, crabapples and
hawthorns. These usually occur in masses in the wild, so use them in groupings
in the landscape. These trees are especially attractive when viewed from
a distance against a backdrop of vegetation.
4. There is little turf on the forest floor. Mulching under trees with
woodchips is not only good for tree growth, it is more reflective of a
natural woodland. Group together smaller trees and shrubs in mulched beds.
5. Plant spring-blooming herbaceous plants or bulbs beneath trees to bring
color to the ground layer. Remember that most of these will go dormant
by summer. Avoid using brightly colored annuals under the trees. Woodland
wildflowers have a delicate beauty that is best appreciated up close.
They normally do not make a big splash of color.
THE PLANTS OF THE EASTERN WOODLANDS
Canopy Trees, Dominant Species
bur oak, Quercus macrocarpa
hackberry, Celtis occidentalis
green ash, Fraxinus pennsylvanica
red oak, Quercus rubra
linden, Tilia americana
American elm, Ulmus americana
Other Species
Ohio buckeye, Aesculus glabra
bitternut hickory, Carya cordiformis
shagbark hickory, Carya ovata
white ash, Fraxinus americana
honeylocust, Gleditsia triacanthos
Kentucky coffeetree, Gymnocladus dioica
black walnut, Juglans nigra
eastern redcedar, Juniperus virginiana
white oak, Quercus alba
chinkapin oak, Quercus muehlenbergii
black oak, Quercus velutina
Understory Trees
redbud, Cercis canadensis
downy hawthorn, Crataegus mollis
eastern wahoo, Euonymus atropurpureus
ironwood, Ostrya virginiana
wild crabapple, Pyrus ioensis
bladdernut, Staphylea trifolia
prickly ash, Zanthoxylum americanum
Shrubs
rough-leaf dogwood, Cornus drummundii
hazelnut, Corylus americana
wild plum, Prunus americana
chokecherry, Prunus virginiana
dwarf chinkapin oak, Quercus prinoides
winged sumac, Rhus copallina
smooth sumac, Rhus glabra
gooseberry, Ribes missouriense
elderberry, Sambucus canadensis
coralberry, Symphoricarpos orbiculatus
Woody Vines
racoon grape, Ampelopsis cordata
bittersweet, Celastrus scandens
virgins bower, Clematis virginiana
Virginia creeper, Parthenocissus quinquefolia
Wildflowers, Spring Ephemerals
spring beauty, Claytonia virginica
Dutchman's breeches, Dicentra cucullaria
trout lily, Erythronium albidum
mayapple, Podophyllum peltatum
bloodroot, Sanguinaria canadensis
Other Wildflowers
columbine, Aquilegia canadensis
jack-in-the-pulpit, Arisaema triphyllum
New England aster, Aster novae-angliae
tall bellflower, Campanula americana
boneset, Eupatorium perfoliatum
blue lobelia, Lobelia syphilitica
woodland phlox, Phlox divaricata
Solomon's seal, Polygonatum biflorum
golden glow, Rudbeckia laciniata
false Soloman's seal, Smilacina stellata
purple meadowrue, Thalictrum dasycarpum
spiderwort, Tradescantia ohiensis
Panhandle Pinelands
Just as the eastern deciduous forest has
a tenuous foothold along the uplands of the Missouri River, outliers of
the evergreen forest of the Rocky Mountains have found a home in scattered
locations in the Nebraska Panhandle. Here, on the bluffs and buttes of
the Pine Ridge Wildcat Hills and other escarpments, the vegetation is
comprised of plants characteristic of the foothills of Colorado and Wyoming.
The signature plant of this region is the
ponderosa pine. In some situations this evergreen tree forms dense, dark
stands of true forest, while in more open areas it provides the framework
for beautiful park-like savannas. Another species, limber pine, occurs
in a small area in Kimball County. These pines have more than just visual
appeal; their fragrance and the sound of the wind through their needlelike
leaves creates a sensory experience completely different from that of
the eastern woodlands.
There is not a great diversity of trees
in these pinelands. Rocky Mountain juniper is a distant second to ponderosa
pine in abundance, and most of the deciduous trees occur in draws and
canyons where the pine is not so dominant. Typical deciduous species include
hackberry, boxelder, cottonwood and green ash, along with the less common
aspen, mountain maple and water birch. Pines do not form an overarching
canopy like oak or linden trees, so there is not an understory layer of
smaller trees as in the eastern woodlands.
A variety of shrubs occur in this landscape,
mostly in openings or at the edges of the forest. Mountain mahogany forms
dense, twiggy stands on rough ground, as does current and aromatic sumac.
Common juniper forms low, evergreen mats of foliage over rocks and in
openings in the forest. Oregon grape, a short broadleaf evergreen groundcover
with holly like leaves, adds interest and beauty to the forest floor.
Fringed sagewort is a silvery, semishrubby plant with spicy-scented foliage
that compliments the fragrance of pine.
The herbaceous members of this plant community
are essentially prairie plants. Away form the influence of the pines,
the vegetation is mixed grass and shortgrass prairie, and is dominated
by low-growing grasses like blue grama and buffalograss. Most of the wildflowers
are short-statured perennials that are very drought-tolerant. Some of
the best shows of wildflowers are in the rockier habitats where the grasses
are not as competitive.
DESIGN IMPLICATIONS
The famous conservationist Aldo Leopold
once wrote, "I love all trees, but I am in love with pines."
Few people would want to be without pines or other evergreen trees in
the landscape. Consider using them in a way that reflects the Panhandle
pinelands.
1. A dense planting of evergreens provides shelter and enclosure, but
a savanna-like mixing of trees with open space is visually more pleasing.
Isolated trees make nice specimens, but in nature pines tend to occur
in groupings that follow the contours of the land.
2. Young pines tend to have branches to the ground, while more mature
trees usually lose some lower branches. Let this process happen at the
tree's pace and avoid the tendency to "limb up" pines to make
it easier to mow around them. Use groupings of pines as a backdrop against
which to mass smaller trees and shrubs.
3. The landscape of the Pine Ridge and Wildcat Hills exhibits dramatic
topographic relief. Cultivated landscapes can reflect this through raised
beds, berming, etc. However, such contouring of the landscape should be
subtle and in keeping with the overall context of the site. Don't get
carried away!
4. Stone is a beautiful part of the Panhandle landscape. When incorporating
it into cultivated landscapes, use only native stone and place it into
the contours of the landscape in a manner similar to its occurrence in
the natural setting. In other words, try to re-create rock outcroppings;
do not make unnatural piles or walls of rock.
5. Most of the native wildflowers of the Panhandle are adapted to hot,
dry growing conditions. These conditions must be met in a cultivated landscape
by providing a well-drained soil. Raised beds and the incorporation of
rock chips and organic matter can help improve soil damage. Since most
of these wildflowers are low-growing, raised beds are an excellent way
to elevate these plants for closer observation by garden visitors.
THE PLANTS OF THE PANHANDLE PINELANDS
Dominant Trees
ponderosa pine, Pinus ponderosa
limber pine, Pinus flexilis
Rocky Mountain juniper, Juniperus scopulorum
Other Trees
mountain maple, Acer glabrum
water birch, Betula occidentalis
hackberry, Celtis occidentalis
green ash, Fraxinus pennsylvanica
cottonwood, Populus deltoides
aspen, Populus tremuloides
Shrubs
juneberry, Amelanchier alnifolia
fringed sagewort, Artemisia frigida
mountain mahogany, Cercocarpus montanus
rabbitbrush, Chrysothamnus nauseosus
hawthorn, Crataegus succulenta
common juniper, Juniperus communis
creeping juniper, Juniperus horizontalis
creeping mahonia, Mahonia repens
sandcherry, Prunus besseyi
chokecherry, Prunus virginiana
aromatic sumac, Rhus aromatica
clove current, Ribes odoratum
western wild rose, Rosa woodsii
buffaloberry, Shepherdia argentea
western snowberry, Symphoricarpos occidentalis
Woody Vines
western clematis, Clematis ligusticifolia
woodbine, Parthenocissus vitacea
Western Prairie Plants, Grasses
western wheatgrass, Agropyron smithii
blue grama, Bouteloua gracilis
hairy grama, Bouteloua hirsuta
buffalograss, Buchloe dactyloides
needle-&-thread, Stipa comata
little bluestem, Schizachyrium scoparium
Wildflowers
pasque flower, Anemone patens
pussytoes, Antennaria parvifolia
evening primrose, Calylophus serrulatus & C. lavandulifolia
harebells, Campanula rotundifolia
golden aster, Chrysopsis villosa
black sampson, Echinacea angustifolia
western wallflower, Erysimum asperum
dotted gayfeather, Liatria punctata
gumbo lily, Oenothera caespitosa
prickly pear, Opuntia polyacantha
locoweed, Oxytropis lambertii
phlox, Phlox andicola & P. hoodii
prairie coneflower, Ratibida columnifera
blue-eyed grass, Sisyrinchium montanum
cowboy's delight, Sphaeralceae coccinea
western spiderwort, Tradescantia occidentalis
vervain, Verbena bipinnatifida
The Prairie
It would be an understatement to say that
Nebraskans appreciate trees. This is the state that gave rise to Arbor
Day and the first statewide arboretum in the country. Yet, prior to settlement,
forests and woodlands accounted for less than three percent of the natural
vegetation of Nebraska. The rest was a landscape without trees - the prairie.
There are several types of prairie in Nebraska,
ranging from the tallgrass prairie in the eastern third of the state,
through the mixed prairie and sandhills prairie in the center, to the
shortgrass prairie of the west. Each type has its own characteristic assortment
of plants, yet there are patterns and features common to all.
The prairie is a plant community dominated
by grasses. It is the fine-textured foliage of grasses, rather than the
trunks and branches of trees, that gives definition to the prairie landscape.
Willa Cather expressed it beautifully in My Antonia, "As I looked
about me, I felt that the grass was the country, as the water is the sea."
After the grasses, wildflowers are the most
abundant plants of the prairie. These nonwoody plants are usually perennials,
meaning they die back to the ground each year after a few frosts, and
re-emerge in the spring. Two families of plants, the sunflower and bean
family, are particularly prominent in the prairie and make up a large
percentage of the wildflowers present. A few shrubs also make a home among
the grasses.
Unlike annual garden plants that produce
flowers all growing season, prairie wildflowers have specific seasons
of bloom. Some bloom very early in the spring, before the grasses begin
to stir, and go dormant by summertime. Others do not start to flower until
late in the summer. This seasonality makes the prairie a very dynamic
landscape.
DESIGN IMPLICATIONS
Capturing the essence of the prairie can
be approached with different levels of intensity. At one level is the
re-creation of a "mini-prairie" by seeding an area with a mixture
of prairie grasses and wildflowers. At the other end of the spectrum is
the use of representative grasses and wildflowers in standard horticultural
ways, like a flowerbed or border, to give a prairie feel to the landscape.
However this desire is carried out, it should be shaped by the natural
attributes of the prairie.
Even though Nebraska's nickname is the "Tree
Planters State," not all "vacant" space needs to be filled
up with trees. The prairie is a place of great vistas and maintaining
open spaces, even if it is a bluegrass lawn, which conveys a sense of
the natural landscape. Such spaces can have more dramatic impact when
deliberately framed by trees and shrubs or when they lead visually to
even more distant vistas.
Grasses define the prairie, so work them
into the landscape as much as possible. Use them as you might use shrubs
- as foundation plantings, accent points, screens, etc.
Capturing a sense of the prairie does not
mean eliminating trees and shrubs from the landscape. A prairie feel can
be accomplished by simply adding beds and borders of prairie plants or
by enhancing existing landscape features with prairie grasses and wildflowers.
While many prairie wildflowers are beautiful
when viewed close up, their greatest impact is en masse. Plant individual
species in sweeps and drifts in the garden and landscape.
The prairie is a very dynamic landscape.
Use a combination of spring-, summer-, and fall-blooming wildflowers and
other perennials to recreate the seasonality of the prairie.
THE PLANTS OF THE PRAIRIE
Grasses
big bluestem, Andropogon gerardii
sideoats grama, Bouteloua curtipendula
sand lovegrass, Eragrostis trichoides
junegrass, Koeleria cristata
switchgrass, Panicum virgatum
little bluestem, Schizachyrium scoparium
Indian grass, Sorghastrum nutans
prairie cordgrass, Spartina pectinata
prairie dropseed, Sporobolus heterolepis
Shrubs
leadplant, Amorpha canescens
Jersey tea, Ceanothus americana & C. herbaceous
prairie wild rose, Rosa arkansana
prairie willow, Salix humilis
Wildflowers
swamp milkweed, Asclepias incarnata
butterfly milkweed, Asclepias tuberosa
aster, Aster oblongifolius, A. ericoides, A. fendleri, A. sericeus
baptisia, Baptisia australis, B. bracteata, & B. leucantha
purple poppymallow, Callirhoe involucrata
prairieclover, Dalea candida (white) & D. purpurea (purple)
plains larkspur, Delphinium virescens
pale purple coneflower, Echinacea pallida
Joe Pye weed, Eupatorium maculatum
sneezeweed, Helenium autumnale
false sunflower, Heliopsis helianthoides
rough gayfeather, Liatris aspera
thickspike gayfeather, Liatris pycnostachya
Missouri primrose, Oenothera macrocarpa
cobaea penstemon, Penstemon cobaea
shell-leaf penstemon, Penstemon grandiflorus
prairie phlox, Phlox pilosa
wild alfalfa, Psoralea tenuiflora
prairie coneflower, Ratibida pinnata
black-eyed susan, Rudbeckia hirta
prairie petunia, Ruellia humilis
blue sage, Salvia azurea
compass plant, Silphium laciniatum
blue-eyed grass, Sisyrinchium campestre
stiff goldenrod, Solidago rigida
showy goldenrod, Solidago speciosa
ironweed, Vernonia fasciculata
prairie violet, Viola pedatifida
Dr. John Weaver, the University of Nebraska's
great prairie ecologist, used to tell his students that to understand
the prairie, they needed "to look carefully and look often."
This is wise council, not only for ecologists, but for horticulturists
as well.
There is great beauty in the natural landscape
of Nebraska if we take the time and make the effort to look closely. Let's
take our inspiration from the beauty that surrounds us and create landscapes
that reflect a sense of place and that celebrate being in Nebraska. Then
we will be landscaping "Nebraska Style."