Plantings for Wet Lowlands

This linear grove of mature trees, many of them nearly one hundred years old, is a planting of native White Oaks (Quercus alba) and Swamp White Oaks (Quercus bicolor).

Imagine the benefit of trees like this along that section of stream you’re mowing or grazing right now.  The Swamp White Oak in particular thrives in wet soils and is available now for just a couple of bucks per tree from several of the lower Susquehanna’s County Conservation District Tree Sales.  These and other trees and shrubs planted along creeks and rivers to create a riparian buffer help reduce sediment and nutrient pollution.  In addition, these vegetated borders protect against soil erosion, they provide shade to otherwise sun-scorched waters, and they provide essential wildlife habitat.  What’s not to love?

Swamp White Oak
Autumn leaf of a Swamp White Oak

The following native species make great companions for Swamp White Oaks in a lowland setting and are available at bargain prices from one or more of the County Conservation District Tree Sales now underway…

Red Maple
The Red Maple is an ideal tree for a stream buffer project. They do so well that you should limit them to 10% or less of the plants in your project so that they don’t overwhelm slower-growing species.
River Birch
The River Birch (Betula nigra) is a multi-trunked tree of lowlands.  Large specimens with arching trunks help shade waterways and provide a source of falling insects for surface-feeding fish.  Its peeling bark is a distinctive feature.
Common Winterberry
The Common Winterberry with its showy red winter-time fruit is a slow-growing shrub of wet soils.  Only female specimens of this deciduous holly produce berries, so you need to plant a bunch to make sure you have both genders for successful pollination.
American Robins feeding on Common Winterberry.
An American Robin feeding on Common Winterberry.
Common Spicebush
Common Spicebush is a shrub of moist lowland soils.  It is the host plant for the Spicebush Swallowtail butterfly and produces small red berries for birds and other wildlife.  Plant it widely among taller trees to provide native vegetation in the understory of your forest.
Common Spicebush foliage and berries.
Common Spicebush foliage and berries in the shade beneath a canopy of tall trees.
Common Pawpaw
The Common Pawpaw a small shade-loving tree of the forest understory.
Common Pawpaw
Common Pawpaw is a colony-forming small tree which produces a fleshy fruit.  It is the host plant for the caterpillars of the Zebra Swallowtail.
Buttonbush
The Buttonbush is a shrub of wet soils.  It produces a round flower cluster, followed by this globular seed cluster.
Eastern Sycamore
And don’t forget the Eastern Sycamore, the giant of the lowlands.  At maturity, the white-and-tan-colored bark on massive specimens makes them a spectacular sight along stream courses and river shores.  Birds ranging from owls, eagles, and herons to smaller species including the Yellow-throated Warbler rely upon them for nesting sites.
Yellow-crowned Night Herons Nesting in an Eastern Sycamore
Yellow-crowned Night Herons, an endangered species in Pennsylvania, nesting in an Eastern Sycamore.

So don’t mow, do something positive and plant a buffer!

Act now to order your plants because deadlines are approaching fast.  For links to the County Conservation District Tree Sales in the Lower Susquehanna River Watershed, see our February 18th post.

Living in the Shadows

They get a touch of it here, and a sparkle or two there.  Maybe, for a couple of hours each day, the glorious life-giving glow of the sun finds an opening in the canopy to warm and nourish their leaves, then the rays of light creep away across the forest floor, and it’s shade for the remainder of the day.

The flowering plants which thrive in the understory of the Riparian Woodlands often escape much notice.  They gather only a fraction of the daylight collected by species growing in full exposure to the sun.  Yet, by season’s end, many produce showy flowers or nourishing fruits of great import to wildlife.  While light may be sparingly rationed through the leaves of the tall trees overhead, moisture is nearly always assured in the damp soils of the riverside forest.  For these plants, growth is slow, but continuous.  And now, it’s show time.

So let’s take a late-summer stroll through the Riparian Woodlands of Conewago Falls, minus the face full of cobwebs, and have a look at some of the strikingly beautiful plants found living in the shadows.

Oxeye (Heliopsis helianthoides) is common on the interior and along the edges of Riparian Woodland.  Specimens in deep shade flower less profusely and average less than half the height of the five feet tall inhabitants of edge environs.
Pale Touch-Me-Not (Impatiens pallida) is one of two species of native Impatiens found in the river floodplain.  Both are known as Jewelweed.  The stems and leaves of the indigenous Impatiens retain a great quantity of water, so life in filtered sunlight is essential to prevent desiccation.  Contrary to popular folklore, extracts of Jewelweed plants are not effective treatments of Poison Ivy (Toxicodendron radicans) contact dermatitis.
Spotted Touch-Me-Not (Impatiens capensis) is typically found in wetter soil than I. pallida.  Both Jewelweeds develop popping capsules which help to distribute the seeds of these annual wildflowers.  “Touch Me Not”, or you’ll be wearing tiny seeds.
Green-headed Coneflower (Rudbeckia laciniata) grows to heights of eight feet in full sun, hence its alternate common name, Tall Coneflower.  In deep shade, it may not exceed two feet in height.  Floodplains are the prime domain of this perennial.
Wingstem (Verbesina alternifolia) normally flowers no earlier than late August.  The bases of the leaves are continued onto the stem of the plant to form wings which extend downward along its length.  This wildflower tolerates shade, but flowers more profusely along the woodland edge.
Great Lobelia (Lobelia siphilitica), or Great Blue Lobelia, is a magnificent wetland and moist woodland wildflower, usually attaining three feet in height and adorned with a plant-topping spike of blossoms.  Invasive Japanese Stiltgrass (Microstegium vimineum) can be seen here competing with this plant, resulting in a shorter, less productive Lobelia.  Stiltgrass was not found in the Susquehanna River floodplain at Conewago Falls until sometime after 1997.  It has spread to all areas of woodland shade, its tiny seeds being blown and translocated along roads, mowed lots, trails, and streams to quickly colonize and overtake new ground.
American Bladdernut (Staphylea trifolia), a shrub of shaded woods, develops inflated capsules which easily float away during high water to distribute the seeds contained inside.
Buttonbush (Cephalanthus occidentalis) is a shrub of wet soils which produces a strange spherical flower, followed by this globular seed cluster.
Common Pawpaw (Asimina triloba) is a colony-forming small tree which produces a fleshy fruit.  It is the host plant for the caterpillars of the Zebra Swallowtail.  The plant and the butterfly approach the northern limit of their geographic range at Conewago Falls.
Common Spicebush (Lindera benzoin) is a widespread understory shrub in wet floodplain soils.  It is the host plant for the caterpillars of the Spicebush Swallowtail (Papilio troilus).
Sweet Autumn Virgin’s Bower (Clematis terniflora) is an escape from cultivation which has recently naturalized in the edge areas of the Conewago Falls Riparian Woodlands.  This vine is very showy when flowering and producing seed, but can be detrimental to some of the understory shrubs upon which it tends to climb.

SOURCES

Long, David; Ballentine, Noel H.; and Marks, James G., Jr.  1997.  Treatment of Poison Ivy/Oak Allergic Contact Dermatitis With an Extract of Jewelweed.  American Journal of Contact Dermatitis.  8(3): pp. 150-153.

Newcomb, Lawrence.  1977.  Newcomb’s Wildflower Guide.  Little, Brown and Company.  Boston, Massachusetts.