Native Plants of Northern Idaho for Landscaping and Restoration (April, 1999)
Idaho Native Plant Society/White Pine Chapter

In recent years, native plant materials have received long overdue attention for applications in home landscaping, land restoration, and wildlife plantings. There are many reasons for the increased enthusiasm for native plants. The desire to decrease water and nutrient inputs has certainly provided impetus. In an area like the Palouse, natives also provide welcome diversity to the relatively limited list of well-adapted ornamentals. This guide was developed in response to inquiries we have received about native plant materials for various applications. Because there is concern that people will dig plants from their native habitat, we have only included species that are available from nurseries or are easily propagated from cuttings or seed. None of the plants listed are rare. Increased interest in the cultivation of native plants will provide incentive for nurseries to expand their selection.

This guide highlights those species for which we have the best, first-hand information, with an emphasis on woody plants.  We define northern Idaho as that portion of the State north of the Salmon River.  We’ve drawn attention to some of our favorites, as well as those that may present problems in certain situations:

* = excellent

** = one of the few select at the top of our list

! = watch out!  May not be suitable for a formal setting.

The caution alert (!) is for home gardeners.  Plants that are too aggressive for the home garden can be the best materials for such applications as erosion control and streambank stabilization.

In addition to those listed, there are many more interesting native plants!  Only a small portion of Idaho’s herbaceous species has been tried. New information is constantly becoming available, so we hope to update and expand this guide within the next couple of years. We would be happy for any feedback you might wish to give.

ACKNOWLEDGMENT:

Much of the information contained in this guide comes from the personal experience of Fred Johnson, former Professor of Forest Resources at the University of Idaho and active member of the Idaho Native Plant Society.

Tall Shrubs (usually over 8 feet)

(All shrubs are deciduous unless noted otherwise.)

Alder, Sitka (Alnus sinuata). This is the alder that forms large glades at mid to upper elevations in the mountains.  It is notable for its very long male catkins and clusters of dainty woody cones. Height can be controlled by vigilant pruning. Why this over the other three species from northern Idaho?  It’s more delicate and flowers later. Other alder species are either trees, or more tree-like (see “Broadleaf Trees”).  30+ years longevity.

Bittercherry (Prunus emarginata).  A small tree or large shrub that will tolerate dry sites.  Small, bright red fruits are unpalatable to humans but utilized by birds.  Requires a sunny spot.  Leaves are “oblanceolate”-rounded at the tips and tapered toward the stem.

Cascara or buckthorn (Rhamnus purshiana).  Small tree; pruning promotes shrub form. Reliable, yellow fall color, otherwise not unusual.

Chokecherry (Prunus virginiana).  Tall, to 40 feet, with long, cylindrical clusters of fragrant white flowers and the familiar, (usually near-black) very tart cherries famed for jellies and syrups.  A major drawback is its tendency to produce new plants from the roots-so give it lots of room to make a colony.  Prominent, black insect galls make stems distinctive in winter.

** Currant, golden (or yellow) (Ribes aureum). One of our very best tall shrubs;  grows to 15 ft in Moscow.  Very early; is in full leaf with gorgeous dangling clusters of bright yellow flowers about the time of first daffodils.

Hawthorn, black (Crataegus douglasii). The dominant shrub of “eyebrows” and other moist sites on the Palouse and the dominant shrub of riparian areas.  Forms dense clumps that make excellent cover for birds and small animals. Very dark blue berries, and thorns 1/2 to 1 inch long. Leaves turn deep crimson to purple-red in fall. Seed germination is low, but plants are available from nurseries.  Some report a severe leaf ailment in Moscow.

Hawthorn, red (Crataegus columbiana). A shrub of streamsides, but warmer environs than black hawthorn. Red hawthorn is found in the canyons of the Snake and Clearwater Rivers. Thorns are 1 to 3 inches long. For some, the attractive, bright-red berries make this preferable to black hawthorn in spite of the longer thorns.

Juniper, Rocky Mountain (Juniperus scopulorum).  See “Conifers”.

Maple, Rocky Mountain (Acer glabrum var. douglasii).  Most northern Idaho maples are this variety. Assumes a tree form if not injured or pruned. Will easily grow to 20 feet or more. Pleasant form and light- to mid-green deciduous leaves; unremarkable gray bark; yellow fall color.

Mock-orange (Philadelphus lewisii).  See “syringa”.

Mountain mahogany, curlleaf (Cercocarpus ledifolius). Small, narrow, evergreen leaves and interesting, feathery fruits. Easily established. Although at home in the dry river canyons, it seems to persist in Moscow. Provides nice contrast to broad-leaf plants. Likely to be very drought-hardy.

Ninebark, Pacific (Physocarpus capitatus).  Less common than P. malvaceus, this is disjunct in Idaho from west of the Cascades.  It can easily reach 15-20 feet. A bit later to flower than its smaller cousin, but otherwise pretty much the same. Will take a high water table and (probably) is not as drought-resistant as P. malvaceus.

Serviceberry (Amelanchier alnifolia).  See “Medium Shrubs”.

** Syringa, or mock-orange (Philadelphus lewisii).  The Idaho State flower. Easily established, it will easily reach 20 ft, so leave lots of room. Delectably perfumed white flowers reminiscent in form and fragrance of orange blossoms. Lots of dead wood to prune and occasional seedlings.

Willow, Scouler’s (Salix scouleriana).  Our local “pussy-willow”, it is equally at home on dry hillsides as along streams. Easily transplanted and grown. Older specimens susceptible to weevils which kill the stem above the attack.

Yew, Pacific (Taxus brevifolia).  See “Conifers”.

Medium shrubs (5 to 8 feet)

Buffaloberry (Shepherdia canadensis).  In northern Idaho, found only in the Kootenai Valley, where there are two fruit-color phases-orange and red. Tiny, very fragrant flowers.

Currant, golden or yellow (Ribes aureum).  see “Tall Shrubs”.

** Currant, red-flowering (Ribes sanguineum).  Although common west of the Cascades, this is one of Idaho’s rarities. Blooms profusely in alternate years, with a few flowers in the odd years;  2 to 3-inch dangling clusters of bright pink flowers. Occasionally sets seed and produces seedlings. Although available from conventional nurseries, if we can get this one going from Idaho seed-great!  Nursery stock will undoubtedly be from coastal plants, however plants from the Puget Sound area appear to be hardy in Moscow.

Currant, snow (Ribes niveum).  Early white flowers and exceptional edible fruits (for Idaho species).  A plant of streamsides in the Idaho bunchgrass zone.  As an ornamental, this is no match for R. sanguineum or R. aureum.

Dogwood, red-osier (Cornus sericea, C. stolonifera).  As an ornamental, primarily valued for its red twigs in winter, but also an excellent plant for stream restoration because of its spreading growth habit and ability to root from cuttings. Will go to 15 feet or more but prunes easily from the base. Easily propagated from stem cuttings.

Elderberry, blackbead (Sambucus racemosa var. melanocarpa).  Early clusters of small, white or creamy flowers.  Needs a rather sunny spot.

Elderberry, blue (Sambucus cerulea). Great clusters of tiny, white or creamy flowers give way to light blue edible berries in fall.  A favorite food of black bears.

Mountain-ash, Rocky Mountain (Sorbus scopulina).  Nice, many-stemmed form. Reliably produces flat-topped clusters of ill-smelling, tiny, white flowers and bright orange-red fruits that attract birds.  Plants with sticky buds have fire-blight resistance.

* Ninebark (Physocarpus malvaceus).  Reliable, two-inch clusters of white flowers in mid-spring; fruit unattractive. Leaves turn reddish-orange some autumns. Also see Physocarpus capitatus under tall shrubs.

** Oceanspray (Holodiscus discolor).  Excellent vase-shaped form when open grown, and also reasonably tolerant of shade.  A late flowering of dense, drooping clusters of tiny white flowers. Good winter form, but some consider the persistent old flower clusters to be unattractive.

! Oregon-grape, tall (Berberis aquifolium). With a natural range barely entering northern Idaho, this holly-leaved evergreen has escaped from cultivation in places, including the Palouse.  Valued primarily for its interesting foliage, it also has great-smelling early yellow flowers and edible (in jelly) blue fruits.  It will go well over  5 feet if left unpruned and is an aggressive spreader by both seed and suckers (get seedlings out before year two or have more trouble extracting them). In harsh winters, winter-killed leaves turn brown and hang on…and on.  For a holly-leaved evergreen with fewer bad habits see “Oregon grape, creeping” under “Low Shrubs”.

Rose, baldhip (Rosa gymnocarpa).  Although a low shrub in the forest understory, attains a height of 8 feet in cultivation. Small, pink flowers are unimpressive.  Armed with dense, soft prickles.

Rose, Nootka (Rosa nutkana).  Bears plenty of 2-inch, pink flowers, but few fruits.

Rose, Wood’s (Rosa woodsii).  Flowers and “hips” in clusters; red stems in winter.  Needs a sunny spot.

Serviceberry (Amelanchier alnifolia).  Earliest flowering of all our native shrubs. White flowers; edible blue fruits similar to huckleberries in form, but not really worthwhile in cultivation.

Sumac, smooth (Rhus glabra).  Distinctive, slowly spreading shrub of canyon grasslands, with attractive open form and large, pinnate leaves similar to “tree of heaven”.  Some say red color of fruits and deep-orange fall foliage are not as good as in the wild.  Full sun.

Low Shrubs (ordinarily under 4 feet)

** Bearberry or kinnikinnick (Arctostaphylos uva-ursi).  This ground-hugging, evergreen groundcover has already been discovered by commercial landscapers.  Though at home in the forest understory, it is very drought tolerant and forms a dense cover of small, leathery leaves. Tiny, pink heather-type flowers.

! Blackberries and raspberries (Rubus species).

Although our native blackberries are more slender and graceful, and less aggressive, than the Himalayan blackberries of roadsides, they can be difficult to control in a home landscape.  However, they may have applications for naturalized areas or wildlife plantings. In addition to the four listed below, other native species include R. idaeus (wild red-raspberry) and R. leucodermis (black-cap raspberry).  This is an interesting instance where the vernacular terms “raspberry” and “blackberry” make a technical distinction that the Latin names do not.  That is, that the fruit of a raspberry separates from the central receptacle when ripe, whereas the blackberries come away with the central receptacle intact.

• Pacific blackberry (R. ursinus).  Our only native blackberry. Slender, trailing stems mostly stay on the ground, but the more vigorous can attain heights of 6 to 8 feet; dioecious (separate male and female plants).  Fruits with excellent flavor.
• Snow bramble or snow dewberry (R. nivalis). An excellent trailing groundcover for shady sites.  Interesting, glossy-green leaves.
• Strawberry bramble (R. pedatus). A plant of the forest understory in the Panhandle. Trails by runners from which it can be propagated.
• Thimbleberry (R. parviflorus). An aggressive spreader with dramatic, large leaves. Delicious, fragile, red raspberries, but produces few flowers in shade.  No prickles.

Kinnikinnick (Arctostaphylos uva-ursi). See “Bearberry”.

* Oregon grape, creeping (Berberis repens, Mahonia repens). Evergreen, holly-like leaves vary from dark green to rose with age and season.  Leaves are dull in texture rather than shiny as in B. aquifolium.  Forms low mounds under 2 feet and spreads slowly. Clusters of bright yellow flowers in spring and waxy blue berries in summer.

Sagebrush, big (Artemisia tridentata). Barely reaching northern Idaho in the Snake River canyon, this icon of the west is desirable for its soft, blue foliage in full sun.  In our area, needs intensive pruning to keep it low (and some say to make it persist).

! Snowberry, common (Symphoricarpos albus). A fairly unremarkable low, honeysuckle-like shrub, but not a climber like its relative, creeping snowberry (S. mollis). Interesting large, white berries remain through winter if not eaten by birds.  Give this plenty of room!  Spreading by underground suckers, it’s quite willing to take over your yard. Useful for naturalized areas and wildlife plantings. Susceptible to powdery mildew in Moscow.

Broadleaf trees

Alders (Alnus species).

Our native alders are streamside plants in the wild and require summer irrigation or a high water table.  They have received little horticultural attention. Flowers are inconspicuous and fall color unremarkable.  Alders fix nitrogen and are valuable for revegetating disturbed sites.

• Alder, red (Alnus rubra).  Although ubiquitous west of the Cascades, this alder species is rare in Idaho.  A tall tree, it is similar to white alder with which it hybridizes.
• Alder, Sitka (Alnus sinuata).  See “Tall  Shrubs”.
• Alder, thinleaf (Alnus incana tenuifolia). Smallest of our tree-type alders, and usually multistemmed, this grows easily, and will likely reach 15 feet or more, but height can be controlled.  Long-lived.  Cones are susceptible to an unattractive smut fungus in our area.
• Alder, white (Alnus rhombifolia). Tall, fast-growing tree of low-elevation river canyons and streamsides.  Nice gray bark. Unusual in cultivation, but there is some evidence that it fares better than either red or thinleaf alder.

! Aspen, quaking (Populus tremuloides).  An extremely attractive, fast-growing tree.  The caution is for home landscapes, as aspen is not suitable for formal settings because of its AGGRESSIVE spread by extensive suckers.  For the same reason, it is an excellent tree for wildlife, stream restoration, and naturalized areas. Available at conventional nurseries.

Birch, river (Betula occidentalis).  Fast-growing, small to medium-sized tree, generally with several stems, and gray bark.  It has smaller leaves than alders and no woody cones.  It grows along streamsides at the western edge of the mountains and along perennial streams of the Palouse and scablands. Hybridizes with B. papyrifera where their ranges overlap.

Birch, paper (Betula papyrifera). Variety subcordata, native to the Clearwater Mountains, does not have the striking white bark for which the species is known. Variety commutata occurs from Coeur d’Alene north, and most mature trees have white bark, which does not develop until trees are at least 15 years old.

Cascara or buckthorn (Rhamnus purshiana).  See “Tall Shrubs”.

Cottonwood, black (Populus trichocarpa).  A fast-grower of northern Idaho streams and rivers.  Glossy, deep-green foliage.  Although not spreading by suckers, it is too big and vigorous for most yards.

Maple, Rocky Mountain (Acer glabrum).  See “Tall Shrubs”.

Conifers

All of our native conifers do well in cultivation except whitebark pine (Pinus albicaulis) which is a very, very slow grower.  In situations where irrigation is not possible, plant trees adapted to your elevation zone.  The following list includes all but a few, high-elevation, species.

Douglas-fir (Pseudotsuga menziesii).  Not a true fir, but with soft, fir-like foliage and interesting cones.

Fir, grand (Abies grandis).  Flat sprays of shiny needles.

Fir, subalpine (Abies lasiocarpa).  The majestic spire-shaped conifer of our highest elevations.  Soft, blue-green needles.  Makes a lovely garden specimen.

Hemlock, western (Tsuga heterophylla).

Juniper, Rocky Mountain (Juniperus scopulorum).  More of a tall shrub than a tree.  Fills an important need in that it is one of only two native conifers that is not a large tree.  Very limited in distribution in northern Idaho, but easily grown.  Its similar-appearing relative, eastern redcedar (J. virginiana) has been widely planted in windbreaks in the western U.S., from which it occasionally escapes.  Numerous cultivars are available, most of which appear more attractive but less natural than the native variety. Sun.

Larch, western (Larix occidentalis). Unique in losing all of its needles each fall, this conifer has great potential for the home landscape.  Graceful branching pattern and open crown; brilliant yellow fall color. New spring foliage is a light bright-green.

Pine, ponderosa (Pinus ponderosa).  The best choice for warm exposures at lower elevations.

Pine, lodgepole (Pinus contorta). Short-needled pine with a wide range of ecological tolerance. Fast-growing but easily trained. Will probably thrive in all but the warmest areas.

Pine, western white (Pinus monticola).  Distinctive for its neat whorls of horizontal branches.  Cultivars available which are 60% blister rust resistant.

Redcedar, western (Thuja plicata).  Dominant tree of northern Idaho, including the wettest sites.  Distinctive for its fibrous bark, fluted base, and drooping, lacey foliage. Not suitable for dry sites.

Spruce, Engelmann (Picea engelmannii).  Associated with cold, wet habitats in the wild.

Yew, Pacific (Taxus brevifolia).  Our native yew is a shrub or small tree with unusual platy bark and very interesting variation of a cone.  Needs summer moisture.

Forbs

A multitude of native forbs (herbaceous plants other than grasses) conform well to the home garden and there are many more for which we have no first-hand information.  The following can provide beautiful and interesting additions to your home landscape.

Camas (Camassia quamash). Does well in full sun, but needs wet feet in spring.  Not persistent.

* Columbine, red (Aquilegia formosa). One of two columbines native to our region. A winner for two reasons: 1) a tall, 4 foot clump with later, red/yellow flowers than most garden types, and  2) it seems not to hybridize with other columbines, producing “pure” seedlings.

* Dutchman’s breeches (Dicentra cucullaria). Very early and very nice. Unique white flowers on ferny foliage.

Fairy-bells (Disporum hookeri and D. trachycarpum). Two- to three-foot leaves with white flowers. Leaves are the most interesting. Does well in shade and remains in place-just gets larger and more stems with age.

! False Solomon’s seal, starry (Smilacina stellata). A good plant for a shady, naturalized setting where the spreading habit isn’t a consideration. Some have found this plant too aggressive for a manicured setting.

False Solomon’s seal (Smilacina racemosa). Taller than starry false Solomon’s seal, and with showier flowers.  Broad leaves on stiffly arching stems and attractive terminal plumes of tiny white flowers. Many, bright red fruits.

Kittentails, evergreen (Synthyris platycarpa). Endemic to the Clearwater Mountains. Round, scalloped, evergreen leaves; delicate, early flowers; and heart-shaped fruits.

** Kittentails, mountain (Synthyris missurica var. major). One of the few Idaho plants suitable for commercial cultivation. Interesting, round, scalloped leaves, 2 to 4 inches across, in a tight cluster. Spikes of bright purple flowers starting with early crocus and continuing until mid-daffodil time. Does better with a bit of shade.

* Lupine (Lupinus polyphyllus). This is one of the parents of hybrid multi-hued garden lupines and well worth cultivating for its spikes of blue/purple flowers. Vigorous plant to 3 ft with flowering stems taller.

Lupine, silky (Lupinus sericeus). Beautiful, silvery-blue, silky foliage and lavender to blue flowers. Sun.

* Meadowrue, purple (Thalictrum dasycarpum). 4 to 5-ft beauty needs moist soil. Delicate, columbine-like foliage.  Doesn’t spread like other species of Thalictrum.

Meadowrue, western (Thalictrum occidentalis). To about 3 ft tall.  Easy to grow, not too rambunctious, and does well in shade. Very attractive leaves, and interesting, but rather inconspicuous, flowers.

! Strawberry, wild (Fragaria vesca bracteata). Wonderfully flavored fruits (“fraises” of French gourmet fame), attractive flowers and leaves, BUT it is super aggressive.  Its sole wish is to populate your yard with a carpet of strawberry plants.

* ! Violet, Canada (Viola canadensis). Very vigorous groundcover blooming with early tulips, but very aggressive and will grow into lawn.

** Violet, Nuttall’s (Viola nuttallii). Early (mid-daffodil time) and BIG yellow flowers. Keeps a compact bunch. Throws occasional seedlings.

Violet, pioneer (Viola glabella). Good, reliable, early, yellow-flowering violet. Not as showy as V. nuttallii, but endures shade better. Makes a colony in a few years, but easy to keep in bounds.

** Wild ginger (Asarum caudatum). A superb ground-cover for light to heavy shade. Heart-shaped, evergreen leaves are rather drab in early spring, but by mid-April they are half-expanded with shiny new leaves. Makes a dense cover. Flowers not obvious, but fun to uncover and show to the uninitiated.

Some plants to avoid in home gardens

These species need lots of room to spread:

• Asters (Aster spp.)
• Goldenrods (Solidago spp.)
• Pearly everlasting (Anaphalis margaritacea)

Ferns

Our native ferns from forest habitats do very well in cultivation.  They are ideal in shade or partial shade, but need summer irrigation to succeed. These species may be available from nurseries that specialize in ferns. There are also several species of rock ferns from dry habitats in northern Idaho that are very difficult to grown in the rock garden.

Ladyfern (Athyrium filix-femina). The common tall fern of wet streambottoms and moist cedar groves. Although it does well in cultivation, it will die back in late summer unless given lots of water.  Male fern is very similar.

** Maidenhair fern (Adiantum pedatum). The most unique of our ferns-lacey fronds about 2 ft tall on black, wiry stems.  Despite it’s delicate appearance, it will do just fine with summer watering. Dies down in winter.

** Male fern (Dryopteris filix-mas). Possibly the most outstanding fern of our forests with 3-ft fronds that are held more upright than other ferns.  Dies back in winter.

** Swordfern (Polystichum munitum). This stout, evergreen fern is the most common fern in northern Idaho and is the one frequently used in floral arrangements.  It is also the most resistant to dry conditions, though it still needs summer watering, and it will do OK in anything but extreme sun positions.

** Swordfern, Anderson (Polystichum andersonii). Not easily found, but a beautiful evergreen fern of some 2.5 ft, with finely dissected fronds and an interesting bulbil near the frond tip.

** Mountain woodfern (Dryopteris austriaca and D. carthusiana). Both beautiful ferns and similar to one another in appearance, but D. carthusiana is evergreen.

Grasses

(The first four are the major components of northern Idaho grasslands)

Bluebunch wheatgrass (Agropyron spicatum, Pseudoroegneria spicata). Along with Idaho fescue, this bunchgrass once dominated the Palouse grassland.  Suitable for dry sites, but not well-suited to controlling erosion, although a rhizomatous form is native to our area. Divergent awns on seedheads are distinctive.

Bluegrasses (Poa spp.). Native bluegrasses are bunch-forming (caespitose) rather than spreading and go by various Latin names including Poa juncifolia, Poa secunda, Poa sandbergii, and Poa ampla.  They are the earliest grasses to green-up and set seed.  Local cultivars are available.

Idaho fescue (Festuca idahoensis). Low clumps of very fine leaves. Does best on cooler aspects.

Junegrass (Koeleria cristata, K. macrantha). A rather inconspicuous but lovely member of our regional grasslands.

Mountain brome (Bromus marginatus). For moist sites and cooler aspects.

Tufted hairgrass (Deschampsia cespitosa). Moist sites.

Local sources of native plants

Buffaloberry Farms (retail and wholesale). 51 E. Lake Fork Rd., McCall ID  83638. bufberry@cyberhighway.com

Plants of the Wild (wholesale).  PO Box 866, Tekoa WA. (509) 284-2848 www.plantsofthewild.com

Prairie Bloom Nursery (retail).  Moscow-Pullman Rd., Pullman WA

University of Idaho Research Nursery. College of Forestry, Wildlife and Range Sciences, University of Idaho, Moscow ID  83844.  www.uidaho.edu/cfwr/forres/nursery/seedlings.htm

For a large selection of ferns

Fancy Fronds. Mail order. PO Box 1090, Gold Bar WA  98251. (360) 793-1472. www.fancyfronds.com

For further information

• Fitzgerald, T., S. McCrea, D. Notske, M. Burtt, and M. Terrell.  Native and Adapted Landscape Plant List for the Inland Northwest.  Washington State University Cooperative Extension, Spokane County, Spokane WA.  99 p.
• Fitzgerald, T. and Michael C. Terrell.  (No date). Landscaping with Native Plants for the Inland Northwest.  Washington State University/Spokane County Cooperative Extension, 222 N. Havana, Spokane WA  99202. (509) 477-2048.
• Johnson, F.D.  1995.  Wild Trees of Idaho.  University of Idaho Press.  Moscow ID.  212 p.
• Kruckeberg, A.R.  1982.  Gardening with Native Plants of the Pacific Northwest.  University of Washington Press.  Seattle WA.  252 p.
• Patterson, P.A., K.E. Neiman, and J.R. Tonn.  1985.  Field Guide to Forest Plants of Northern Idaho.  USDA Forest Service, Intermountain Research Station.  General Technical Report INT-180.  246 p.
• USDA, NRCS Plant Materials Center, Pullman WA.