A mosaic of vibrant folk culture, bustling industry, and rich national heritage, the Commonwealth of Pennsylvania has been a vital component of America’s framework since its earliest days. This foundational role earned it the nickname, the ‘Keystone State,’ and the symbol– of the central stone at the summit of an arch that locks the whole thing in place– is still relevant today.
PA boasts the most diverse economy in the country, world-class healthcare and higher education institutions, and exceptional quality of life. These feats would be impossible without the services provided by the state’s wildlife systems, which are often taken for granted until they are damaged.
Ecosystems provide us with material benefits such as food, fuel, medicine, and clean water; regulating services like pollination, pest management, and carbon sequestration; cultural services; and essential supports in the form of habitat and biodiversity maintenance. Without these indispensable ecological services– and the indigenous flora and fauna that lend them– our world would become barren and desolate.
Like nations and masonry arches, ecosystems have keystones too. Research tells us that a small percentage of native plant genera supports the majority of insect species critical to food web stability (notably Lepidoptera and pollen-specialist bees). Without keystone plants, ecosystems collapse.
Encouraging data analysis done on suburban properties in southeastern Pennsylvania shows us that gardening with native plants can mitigate biodiversity loss in human-dominated landscapes. Anyone with plantable space (including cityscape container gardens) can create a miniature ecosystem that performs all major ecological services and offers up an oasis for wildlife. Shrubs can be particularly useful, as they are compact enough to fit into a home landscape, but still have enough biomass to make a difference. Here are some of the best and most beautiful native shrubs that earn their place in any PA garden.
1) Low sweet blueberry (Vaccinium angustifolium)
Touted as producing the tastiest of all blueberries by many in the business, low sweet blueberry is a sprawling deciduous shrub with outstanding wildlife value and eye-catching ornamental qualities. At just 6 – 24 inches tall, this species is a condensed version of its cousin, the highbush blueberry (Vaccinium corymbosum) which can reach 12 feet and is often cultivated by commercial growers in Pennsylvania.
Vaccinium angustifolium is relatively low-maintenance and is suitable for mass plantings, containers, and wildlife gardens– it’s also stunning as a groundcover. Its waxy white or shell-pink urn-shaped flowers bloom from March – June, and are an important floral resource for early spring pollinators like bumblebee queens and mining bees. These native bees have evolved alongside blueberry plants, and are able to vibrate their anthers at a specific frequency (something invasive honeybees can’t do) in a process called sonication or buzz pollination that effectively releases showers of pollen.
Vaccinium is a keystone genus of Eastern Temperate forests that supports 14 species of pollen-specialist bees and 217 species of Lepidoptera, including the Polyphemus silk moth (Antheraea polyphemus) and the red-spotted purple butterfly (Limenitis arthemis). The critically imperiled frosted elfin (Callophrys irus) and the ruby-throated hummingbird (Archilochus colubris) are known to visit the blossoms for nectar. A slew of birds and mammals feast on the nutritious buds and berries– they are particularly valuable to songbirds, gamebirds (especially ruffed grouse and spruce grouse), black bears, and red foxes.
Vaccinium angustifolium is able to self-pollinate, but fruit production improves when multiple genetically variable specimens are planted together. This species has a spectacular fall color that ranges from crimson to plum– it’s especially striking when planted en masse. Low sweet blueberry likes moist to droughty acidic soils with lots of organic matter and good drainage. It is found nearly throughout Pennsylvania in open coniferous woods, old fields, and on sandy or rocky balds. A pH test is recommended for home growers before planting, and elemental powdered sulfur can be used to help soil reach the ideal 4.5 – 5 range– avoid using peat moss, as its harvest can endanger vulnerable wetland ecosystems.
2) Pussy willow (Salix discolor)
One of the first harbingers of spring in the northeast, the soft, silvery-gray catkins of the American pussy willow appear on bare stems in late winter. Salix discolor is the first willow to come into flower each year, blooming February – May with male and female catkins on separate plants. Females will have slender, greenish nectar-rich pistils, while the males produce showy golden stamens with abundant pollen (and nectar at their base). Hummingbirds and other songbirds use the velveteen ‘fur’ to line their nests. The buds are an important winter food for ruffed grouse, while ducks and other waterfowl eat the mature catkins.
14 pollen-specialist bees depend on the genus Salix, while a whopping 289 species of Lepidoptera use it as a larval host– these include the huge and beautiful cecropia moth (Hyalophora cecropia), the Io moth (Automeris io), the eastern tiger swallowtail (Papilio glaucus), the viceroy (Limenitis archippus), and the mourning cloak butterfly (Nymphalis antiopa), amongst many others. This multitude of caterpillars provides a smorgasbord for songbirds, while pussy willow’s dense growth habit and rounded crown offer excellent cover and nesting habitat. This species is a must-have for bird or pollinator gardens. It’s also great for erosion control or rain gardens, as its root system is extensive and vigorously seeks out moisture (for this reason, avoid planting it near water lines, sewer lines, or septic tank fields).
Salix discolor is a fast-growing deciduous perennial shrub that reaches 12 – 15 ft tall and 8 – 10 ft wide– it can be pruned heavily (to 6 – 12 in) every few years to encourage fresh new growth and a bountiful bloom in the following season. Its flowering branches are highly sought after for spring floral arrangements. Pussy willow prefers full to partial sun and likes nearly any damp soil, including clay– it can be planted simply by sticking a cutting in the wet ground. It tolerates seasonal flooding but may sucker aggressively in consistently moist sites. It is found in marshy lowlands, wetlands, and roadside ditches in most PA counties. Consider also the more compact and drought-tolerant prairie willow (Salix humilis).
3) Atlantic ninebark (Physocarpus opulifolius)
A deciduous shrub cultivated for its year-round interest, the Atlantic ninebark is named for its handsome exfoliating bark, which peels endlessly in ribbons as if the plant had ‘nine lives.’ Each curly strip reveals new sandy brown or cinnamon-colored layers that lend unbeatable texture and contrast to a winter garden. Ninebark’s recurved branches reach 5 – 8 ft tall and spread 4 – 6 ft wide, giving it a pleasing fountain shape. Its twisty limbs also create plenty of nooks and crannies for songbirds to roost or nest in.
Spring brings profusions of showy white (sometimes baby pink) flowers characteristic of the Rosaceae family, with 5 rounded petals, 5 triangular sepals, and numerous stamens fused into a shallow yellow cup– they’re borne in dome-shaped terminal clusters 1 – 2 in wide. These nectar-rich blossoms bloom May – June and are visited by beneficial insects before giving way to persistent papery sacs (the genus name comes from from the Greek physa ‘bladder,’ and karpos ‘fruit’ in reference to the follicles) that turn shiny red and split open in the fall to reveal 2 – 5 seeds.
Ninebark is a larval host for many Lepidoptera species, including the ninebark pygmy moth (Nepticula opulifoliella) and the unicorn caterpillar moth (Schizura unicornis). The flashy ninebark calligraphy beetle (Calligrapha spiraeae) also specializes in its foliage. The leaves themselves are maple-like and dark green (the specific epithet opulifolius notes their similarity to the leaves of Viburnum opulus), turning bronzy-yellow in fall. Ninebark is present throughout PA except for a few northern counties– it occurs in damp woods and on sandy or rocky shores. In a home landscape, it thrives in a variety of light and soil conditions. It is highly drought-tolerant and disease-resistant. Renowned woody plant expert Michael Dirr remarks that “the species is adaptable to all conditions, probably even nuclear attacks, and once established, requires a bulldozer for removal.”
4) Winterberry holly (Ilex verticillata)
Bringing peerless drama to drab winter landscapes, winterberry holly’s bare boughs are bundled with dense clusters of incandescent red berries so bright they glow in afternoon light– particularly against a snowy backdrop or when glazed in ice. They often hug the branches through February (if they aren’t cut for holiday wreaths, garlands, or porch pots). The scarlet fruits (technically drupes), which usually mature by late summer, are remarkably persistent in part because they contain bitter-tasting chemical compounds that don’t break down until the plant has experienced several hard frosts– they are at their freshest and tastiest in the coldest days of winter, when birds need them the most! Though toxic to humans and pets if ingested, winterberries can be literal lifesavers for our feathered friends; they are eaten by at least 48 species of birds, including bluebirds, cedar waxwings, robins, thrushes, and mockingbirds.
Only female plants produce berries– like most hollies, Ilex verticillata is dioecious, with male and female flowers (both small, white, and inconspicuous) on separate plants. For fruit set, at least one male should be planted within 40 ft of every 5 – 7 females. Local ecotype plants will be better adapted to regional microclimates and are your best bet for sustaining wildlife, but if you’re using cultivars you will need matching pairs with overlapping blooms (flowering ranges from April to July).
Winterberry holly is deciduous, and its leaves are smooth and leathery, lacking the sharp teeth characteristic of its evergreen cousins. Its fall foliage is yellow with a purple tinge to the edges. The wild type may reach 20 ft tall, but it grows slowly and typically matures between 6 – 10 ft.
Winterberry is versatile and adapts to both wet and dry sites; it occurs nearly throughout the Commonwealth in wetlands and along riparian corridors. In a garden setting, it does best in full sun to partial shade and moist, well-drained acidic soils. It tolerates clay and inundation, but may suffer from chlorosis (yellowing of its leaves) in alkaline sites. It’s terrific for foundation plantings, mixed borders, or hedges.
5) Mountain laurel (Kalmia latifolia)
Boasting the state flower, mountain laurel or calico bush is like something out of a fairytale; it is usually multi-trunked with gnarled, crooked limbs, glossy evergreen leaves, and enchanting corymbs of parasol-shaped white (or pink-washed) blossoms with subtle magenta markings on the interior of the corolla. In PA it grows in rocky or sandy woods, cool meadows, pastures, and on balds or slopes; it is present in all but two northwestern counties. It can sometimes form dense thickets known colloquially to foresters and lumbermen in southern states as ‘laurel hells.’
In Penn’s Woods, groves of mountain laurels are celebrated; the Laurel Festival, which each year crowns a Laurel Queen, has been held in Brookville (Jefferson County) annually since 1936, drawing large crowds every summer (peak bloom is from May to July). The shrub experienced so much popularity as an ornamental in the early 20th century that efforts were mobilized to protect it from overharvest: a 1913 booklet published by the New York Botanic Gardens admonished, “[…] laurel are being shipped in carload lots by dealers from the mountains of Pennsylvania and the southern Alleghenies, who supply florists and nurserymen from wild sources. How long can they last?” The myth that it is illegal to pick mountain laurel flowers persists to this day.
The blooms of Kalmia latifolia are chiefly pollinated by bees and large moths (Sphinx kalmiae, the laurel sphinx moth, also uses the shrub as a larval host), but are also visited by hummingbirds and butterflies. All parts of the plant are highly toxic, and even honey made from its nectar is poisonous if ingested. Deer leave it alone– mostly.
This intoxicating shrub is a delightful addition to home landscapes as the focal point of a woodland garden or massed-in borders. It reaches 13 – 15 ft high but is often shorter. Optimal growth occurs in partial shade and moist, acidic well-drained soils. It adapts well to a variety of site conditions. Consider also sheep laurel (Kalmia angustifolia) and bog laurel (Kalmia polifolia).
6) Roseshell azalea (Rhododendron prinophyllum)
One of the loveliest of the native azaleas, roseshell or early azalea is a deciduous perennial shrub found throughout much of the Commonwealth in dry woods, thickets, and on talus and rocky slopes. Though it prefers evenly moist, humusy well-drained soils, it is extremely hardy, with marked tolerance to high pH (most azaleas suffer from chlorosis without strongly acidic site conditions). It has an open, airy growth habit and graceful, upward-arching branches. Like all rhododendrons, it may become leggy and flower poorly if planted in deep shade– it performs best in partial sun. The vivid pink, trumpet-shaped blossoms have a spicy, clove-like fragrance and distinctive protruding stamens.
Roseshell azalea blooms May – June and is a good source of nectar for butterflies, hummingbirds, and bees. Flowers appear in clusters of 4 – 13, either before or with the new leaves. Foliage is smooth and bluish-green, with woolly undersides, and turns a deep burgundy color in the fall. Roseshell azalea is outstanding for foundation plantings, woodland gardens, and bird or pollinator habitats– it is also suitable for containers. It grows 3 – 8 ft tall (rarely to 15 ft).
This species can be susceptible to disease and damage from insects, but a healthy plant in an appropriate cultural environment should have limited problems. Other PA-native azaleas to consider include pinxterbloom azalea (Rhododendron periclymenoides), swamp azalea (Rhododendron viscosum), piedmont azalea (Rhododendron canescens), and smooth azalea (Rhododendron arborescens). All rhododendrons contain toxins that can result in serious poisoning if any part of the plant is ingested.
7) Black chokeberry (Aronia melanocarpa)
Long cultivated by Indigenous Americans for its edible and medicinal properties, black chokeberry is experiencing a new vogue; its plump, purplish-black berries (technically pomes) are considered one of the richest known sources of antioxidants, surpassing currants, gooseberries, blueberries, cranberries, and elderberries. These superfruits are notoriously astringent (hence the common name), but their taste improves tremendously when they’re simmered with a little bit of sugar. Many people enjoy them in jellies and preserves, smoothies, muffins, and even cocktails.
Black chokeberry also happens to be a top-notch addition to both formal landscapes and habitat gardens. Handsome and neatly mounded, it reaches 3 – 6 ft tall with slender limbs, reddish-brown bark, and glossy, finely-toothed leaves. Creamy white, self-fertile flowers with red-violet anthers appear May – June and are visited by bees (especially mason bees and Andrenid bees), butterflies, and other pollinating insects. 29 species of Lepidoptera, including the red-spotted purple (Limenitis arthemis) and the coral hairstreak (Satyrium titus) use it as a larval host. Songbirds, gamebirds, black bears, foxes, and small mammals feed on the fruit.
Black chokeberry has fantastic crimson fall foliage and makes an excellent deciduous hedge or border shrub. It grows wild nearly throughout Pennsylvania in damp woods, lowlands, and bogs, but also in drier thickets or clearings and on bluffs. In a home landscape, it prefers full sun and moist well-drained soils but adapts well to a variety of site conditions. It tolerates flooding, salt, and some urban pollution. This species suckers slowly, but profusely– it can be easily propagated from the shoots. Black chokeberry hybridizes naturally with red chokeberry (Aronia arbutifolia), yielding purple-fruited chokeberry (Aronia x prunifolia)– all three are native to PA.
8) Mapleleaf viburnum (Viburnum acerifolium)
Unusual fall hues of rich mauve and watercolor pink make mapleleaf viburnum a standout in home landscapes. Cultivated as an ornamental since 1736, Viburnum acerifolium is also remarkable for its showy flat-topped flower panicles (composed of numerous tiny white blossoms) borne on velvety sprigs, and its brilliant red berries that ripen to blue-black in late summer. Both its common name and its specific epithet refer to the maple-like shape of its pointy three-lobed leaves. Stately and versatile, this low-growing deciduous shrub is terrific in a garden setting as a hedge, specimen, or foundation plant.
Its substantial wildlife value also makes it a highly functional species for a habitat garden. The fruits (technically drupes) are eaten by white-tailed deer and small mammals, ruffed grouse, ring-necked pheasants, wild turkeys, and many songbirds. The twigs and foliage are browsed by deer, moose, rabbits, and beavers (so it’s a good idea to protect young plants with fencing while they are becoming established). At least 11 species of Lepidoptera use Viburnum as a larval host, including the spring azure butterfly (Celastrina ladon) and the green marvel moth (Agriopodes fallax), while the nectar and pollen of A. acerifolium’s fertile flowers attract bees (especially Halictid and Andrenid bees) and other insect pollinators June – August.
In Pennsylvania, mapleleaf viburnum is common in forests and woodlands throughout the state– it has a high drought tolerance and will grow in deep shade and acidic soils, but optimal growth occurs in partial sun and well-drained, moist loams. It reaches 4 – 6 ft tall and will spread by rhizomes to form colonies if suckers are not removed. Viburnums fruit best when they can be cross-pollinated by another (genetically variable) individual of the same species. Other PA-native viburnums to consider include nannyberry (Viburnum lentago), possumhaw (V. nudum), blackhaw (V. prunifolium), and downy arrowwood (V. rafinesquianum).
9) Spicebush (Lindera benzoin)
Delicate chartreuse blossoms on bare speckled branches are a herald of spring in northeastern deciduous woods, where spicebush is regarded as the “forsythia of the wilds.” A medium-sized shrub 6 – 15 ft tall, Lindera benzoin has slender gray-brown limbs and a graceful, rounded form. Its oval leaves are bright green and glossy, turning a golden-yellow color in the fall. Female plants that have been cross-pollinated by a nearby male will produce greenish fruits that mature into shiny red drupes when the foliage starts to change. The berries, leaves, and twigs are all aromatic when crushed between the fingers, emitting a spicy fragrance (and flavor) that is reminiscent of allspice and pepper.
The twigs and leaves make a fine tea, and the ripe fruits can be dried and used to season food if the birds don’t get to them first– robins and catbirds are especially fond of them. Lindera is a larval host for the fascinating spicebush swallowtail butterfly (Papilio troilus), a species that employs Batesian mimicry; its caterpillars resemble bird droppings or tiny green snakes in their various instars and roll themselves into little ‘leaf tacos’ to hide from predators. The promethea moth (Callosamia promethea) and the tulip tree beauty (Epimecis hortaria) also host on the foliage. Deer leave it alone.
Spicebush adapts well to a variety of soil and light conditions but will perform best in partial shade and rich, moist loams. Avoid letting it dry out, particularly if it’s exposed to full sun. Planting a group of 3 – 5 shrubs should ensure berry production and provide the best benefit to wildlife. Spicebush is lovely in naturalized or woodland gardens and as a specimen, foundation, or accent plant.
10) Silky dogwood (Cornus amomum)
One of our fastest-growing native shrubs, silky dogwood is a vigorous, highly adaptable species found along stream banks and in moist woods, fields, and thickets throughout the Commonwealth. It is markedly similar in appearance to its cousin the red-osier dogwood (Cornus sericea or Cornus alba var. stolonifera), and the two often share habitat (though red-osier is native to fewer PA counties). C. amomum’s twigs are a deeper red than those of C. sericea, and are covered in a soft, downy pubescence that gives them a rosy sheen. Both species have large, flat-topped clusters of cream-colored flowers that give way to snow-white berries (drupes), though silky dogwood’s fruits take on a metallic blue hue as they ripen in August – September. After 1 – 2 years, the stems of C. amomum will have pale brown pith (versus the white pith of our other native dogwoods).
Silky dogwood’s rapid growth (to 15 ft), stoloniferous roots, and exceptional layering capabilities allow it to form a solid hedge in quite a short amount of time; it is a superlative species for windbreaks, wildlife borders, streambank protection, rain gardens, or erosion control. Many songbirds, gamebirds, and small mammals feast on the abundant fruits, and the dense brush offers optimal cover for nesting or roosting. 98 species of Lepidoptera, including azure butterflies (Celastrina spp.) use Cornus as a larval host, and silky dogwood’s May-blooming flowers provide nectar for pollen-specialist bees, butterflies, and hummingbirds.
The deciduous foliage turns red or purple in the fall. C. amomum prefers partial sun but will adapt to most light conditions– it will show stress if its roots begin to dry, and performs best in moist, acidic soils. It tolerates clay and poor drainage. Other shrubby native Cornus species to consider include the pagoda dogwood (C. alternifolia), gray dogwood (C. racemosa), and bunchberry (Cornus canadensis).
If you’re from Pennsylvania and have some experiences with native shrubs, maybe some we missed from our list, do share your knowledge in the comments!