native plants – Greenburgh Nature Center

November 15, 2023November 27, 2023 greenburghnaturecenter Around the Grounds, Invasives, Native Plants, Pollinators

Privacy Without “O-fence”

Suburban yards are places for families and friends to relax, perhaps enjoy a barbecue, and watch children and pets play safely. Privacy is important.

No wonder, then, that suburban homeowners often decide to plant a “privacy screen.” Hedges of trees or shrubs, planted as living “green fences,” are as common in suburbia as the lawns they typically surround.

But too often, these hedges are made with invasive plants that spread themselves into natural areas causing ecological harm. Top offenders include privet, Japanese barberry, forsythia, bamboo, and burning bush. All of these plants are recognized as invasive species and should be avoided.

Forsythia is not a good choice for a privacy screen

Burning Bush — Burning bush may look good for a minute

Japanese barberry, now banned in several states, spreads by seed into vacant lots, woods, and roadsides and actually increases the population of ticks carrying Lyme disease!

The good news is that the need for privacy does not require bringing any of these offensive plants onto your property. There are so many better choices!

In the Eastern US, the most popular privacy screen by far is Arborvitae (Thuja occidentalis), also known as Northern White-cedar. Favored by builders and landscape maintenance companies, a row of inexpensive and readily available Arborvitae is often planted along the property line as soon as a new house is built.

Though Arborvitae is a much better choice than any of the invasive plants mentioned above, it is not the only — or best — option. In areas populated by deer, Arborvitae is extremely vulnerable.

Here are some alternatives – beautiful evergreen trees and shrubs, native to the Northeast, that make ideal privacy screens. And because they are native, they also offer value to native birds and pollinators!

American Holly (Ilex opaca) makes a dense, evergreen privacy screen and has the bonus of tiny flowers for pollinators in the spring and beautiful berries that add winter interest to the landscape.

American Holly may be pruned into a hedge

Rhododendron is another good choice for privacy. When European settlers first explored the Eastern US, they struggled through massive stands of Rhododendron maximum that formed impenetrable evergreen thickets. Why not use that same feature now as an effective screen? Our native songbirds love to hide in a thicket!

Inkberry (Ilex glauca), another native evergreen, grows quickly and has shiny, dark green leaves that form a dense screen. More winter-hardy than boxwood and growing taller, Inkberry is a great hedge plant.

Red Twig Dogwood and Switch Grass — Inkberry in a mixed border with Red Twig Dogwood and Switch
Grass

The very best privacy screen, though, is not a row of one species of plant, but a forest! The Northeastern US was once predominantly forest, and many of the plants in those forests are still the best plants to grow here. In suburban yards, we can mimic the beauty, seclusion, and peaceful quiet of a diverse forest simply by planting more stuff! And a bigger variety of
that stuff is inspired by our native forests!

Maybe it’s time to reconsider our approach to the “privacy screen.”

Hedges can be great, but they can also be visually boring and ecologically sterile. There is no law requiring homeowners to mark their property boundaries with a row of identical plants. Just because your property line forms a rectangle doesn’t mean your landscape has to be one. A diverse mix of plants – native trees, shrubs, grasses, and perennials – planted in masses makes a landscape interesting, lush, ecologically valuable, and very private.

Contrasting approaches – the mixed border of deciduous and evergreen trees on the right offers more interest, and more privacy, than the hedge on the left

white pine, arborvitae, spruce, juniper, and Rhododendron — A mix of White Pine, Arborvitae, Spruce, Juniper, and
Rhododendron completely screens a house from the road

If you already have a hedge or a fence along the property line, consider planting inside it using a mix of native trees and shrubs that change with the seasons. Start with the corners.

Trained landscape designers tend to avoid square corners and straight lines in their designed plantings. You can do the same thing. Map out curved beds that soften the corners and bring more plants further into your yard. Plant taller shrubs at the back, and choose flowering shrubs and perennials to plant in the foreground where you can enjoy them.

Fences along two neighboring properties meet to form a hard corner that is softened, and completely screened, by a curved planting of mixed trees, shrubs, and perennials

So, consider creating a privacy screen that looks more like a forest than a fence. By planting more plants, and a bigger variety of plants in more of your yard, you will have more privacy, more seasonal interest, less lawn to tend, and more habitat for birds, butterflies, and fireflies.

How’s that for a win-win-win-win?!

THIS BLOG IS AUTHORED WEEKLY BY CATHY LUDDEN, CONSERVATIONIST AND NATIVE PLANT EDUCATOR; AND BOARD MEMBER, GREENBURGH NATURE CENTER. FOLLOW CATHY ON INSTAGRAM FOR MORE PHOTOS AND GARDENING TIPS @CATHYLUDDEN.

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November 2, 2023November 27, 2023 greenburghnaturecenter Around the Grounds

Autumn Wonderland

The Northeastern United States is famous for fall foliage. “Leaf peepers” come from all over the world to see our native plants in their dramatic fall colors.

Why, then, should a walk around suburban neighborhoods, in the same region during the same season, be so disappointing? Where are the colors?

The plants that thrill “leaf peepers” grew in abundance before the suburbs were developed, and they would still thrive here – if only they were planted! It seems that every suburban yard uses the same non-native “foundation plants” — boxwood, pachysandra, ivy, and hedges of yew or privet or even bamboo! – all completely devoid of our famous fall colors!

C’mon people! We can do so much better than this! Why not plant our yards with the same trees, shrubs, and perennials that make this region a tourist attraction in the fall? Let’s add some color, life, and seasonal interest beyond pumpkins! There are so many great choices with our incredible abundance of Northeastern native plants.

Red maple (*Acer rubrum*)
Photo: Michael Martini

The undisputed rock-stars of fall color are our native Maples, and Oak trees are a close second. If you have a lawn, you probably have room for a Maple or a native Oak. Oaks have enormous value for wildlife — and for homeowners! [See this blog post] Both Maples and Oaks are beautiful year-round, but autumn is their glory season.

Our native flowering trees are also brilliant in the fall. Nothing beats the American Dogwood (Cornus florida) with its intense maroon foliage and vivid scarlet berries. Crabapples (Malus spp.) also produce colorful fruit, and American Witch Hazel (Hamamelis virginiana) starts blooming in October!

The Northeast is also blessed with native shrubs that produce kaleidoscopic colors in the fall. While evergreen foundation shrubs are useful, why not add some of the flowering and fruiting native shrubs that bring color and interest in both spring and fall? Here are some easy choices to add to your yard. All of the shrubs pictured below are locally available, easy to grow, valuable to wildlife, have beautiful flowers, and are spectacular in the fall.

Oakleaf Hydrangea (*Hydrangea quercifolia*)

Possumhaw Viburum (*Viburnum nudum*) pictured with
American Witch Hazel

Low Bush Blueberry (*Vaccinium angustifolium*)

American Cranberrybush (*Viburnum trilobum*)

And don’t forget fall flowers and grasses in gorgeous colors!

Aromatic Aster (*Symphyotrichum oblongifolium* ‘Raydon’s Favorite’)

Switch Grass (*Panicum virgatum* ‘Cheyenne Sky’) shown with Ironweed (*Vernonia lettermanii* ‘Iron Butterfly’)

Not only are these plants beautiful, they are incredibly valuable to the ecosystem of the Northeastern US. So many suburban landscapes use non-native plants that offer nothing to birds, butterflies, bees and other insects, and many are destructively invasive as well. If your only fall color is coming from burning bush or Japanese maple, you may want to consider native alternatives for those reasons. Privet, bamboo, ivy, vinca, and pachysandra are all known to be invasive plants and can be replaced easily with native plants that are beautiful in the fall, and year-round.

And wouldn’t you enjoy an autumn view like this?

Willow leaf oak (*Quercus phellos*), American dogwood,
and Pin Oaks

And this?

Oaks, Inkberry (Ilex glabra), Blue Star (Amsonia tabernaemontana and A. hubrichtii), High Bush Blueberry(Vaccinium corymbosum), Common juniper, and Possumhaw Viburnum

The fall glory of native plants lies within your reach!

THIS BLOG IS AUTHORED WEEKLY BY CATHY LUDDEN, CONSERVATIONIST AND NATIVE PLANT EDUCATOR; AND BOARD MEMBER, GREENBURGH NATURE CENTER. FOLLOW CATHY ON INSTAGRAM FOR MORE PHOTOS AND GARDENING TIPS @CATHYLUDDEN.

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June 1, 2023June 1, 2023 greenburghnaturecenter Around the Grounds, Native Plants

Pardon the Interruption…

Can a garden plant connect us to a past so unimaginably distant that Earth itself was unrecognizable?

If we interrupt our routines, just for a moment, we can consider a plant that links us to an ancient time. Osmunda claytoniana, commonly known as “Interrupted Fern,” looks perfectly at home in a modern garden, yet it is essentially the same plant it was over 200 million years ago! Even before the first T-rex appeared, Interrupted Fern inhabited lush woodlands on proto-continents that later splintered, collided, and drifted apart.

A fossil found in Antarctica tells the story. In the late Triassic period (252-201 million years ago), the land mass that is now Antarctica had a temperate climate. There, growing near a stream in a shady forest, an Interrupted Fern became encased in sediment and then fossilized. The fossil reveals a plant that is virtually indistinguishable from Interrupted Ferns growing in gardens and forests in the Northeastern US today! Most plant and animal species found on Earth in the Triassic became extinct millions of years ago. Of those that survived, most have undergone so many mutations and evolutionary changes that they are virtually unrecognizable. But Interrupted Fern has continued – essentially without interruption!

Osmunda claytoniana is called “Interrupted Fern” because of its unusual and readily-identifiable structure. While most ferns carry their spores on separate stems or on the undersides of leaves, Interrupted Fern sends up fertile spore-bearing fronds from the center of the plant with feather-like clusters of “sporangia” in mid-stem. As the spore clusters ripen and drop away, the mid-section of the frond is “interrupted” leaving bare space between the leaves.

**Spore-producing structures interrupt the leaves on fertile fronds**

**As spores mature, they dry up and drop away**

**The fertile fronds are left “interrupted” between leafy sections**

Interrupted Fern is a great landscape plant. It emerges in early spring and remains fresh and upright throughout the summer, making an architectural statement in the garden. The fronds typically reach about 3 feet in height, and form an attractive vase shape. The fern expands its territory from the rhizome slowly, over a decade or so, eventually forming a clump. Once established, a clump of Interrupted Fern can be very long-lived. Thriving examples have been found in gardens abandoned for over fifty years. A colony of a naturally-occurring hybrid between Interrupted Fern and its close relative, Royal Fern, in Virginia is thought to be about 1,100 years old.

**A 30-year-old clump of Interrupted Ferns looks great under mature trees along a driveway in suburban New York**

Though it once lived in Antarctica, Interrupted Fern is found today only in Eastern and Central US and Canada. It does best in rich, moderately damp acid soil in full to part shade, but it grows taller (4-5 feet!) with more sun. Hardy in Zones 3 to 7, it is not palatable to deer – or dinosaurs, apparently. It provides cover to small birds and mammals, and makes an excellent underplanting for trees, especially at the edges of wooded areas where leaves are allowed to remain in place, enriching the soil.

Interrupted Fern dies back to the ground in late fall, leaving a mounded crown at the surface of the soil and a network of fine roots below. The rhizome can be dug for transplanting with a sharp spade in early spring by cutting the roots 4 to 6 inches from the crown and settling the crown in the new spot at the same height, spreading the roots out under a light layer of soil. Leaf mulch or compost are much better than bark mulch for keeping the soil moist and cool. In spring, the fronds emerge covered with long, fuzzy hairs and unfurl over a week or so. Once established in a suitable spot, Interrupted Fern really needs nothing more from humans!

**From dinosaurs to automobiles, a living fossil in the modern world**

As we worry about climate change, destruction of habitat, and the alarming loss of plant and animal species in what scientists are calling the “Sixth Great Extinction,” there is some comfort in observing this lovely plant that has seen more than one apocalypse and managed to survive unchanged. This ancient fern may just survive it all.

THIS BLOG IS AUTHORED WEEKLY BY CATHY LUDDEN, CONSERVATIONIST AND NATIVE PLANT EDUCATOR; AND BOARD MEMBER, GREENBURGH NATURE CENTER. FOLLOW CATHY ON INSTAGRAM FOR MORE PHOTOS AND GARDENING TIPS @CATHYLUDDEN.

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April 6, 2023April 14, 2023 greenburghnaturecenter Around the Grounds, Native Plants

A Perennial Star

It won’t be long now…the show is about to start!

Each spring, excitement builds as Eastern Bluestar (Amsonia tabernaemontana) breaks ground and gets ready for its performance, which happens in three acts! Amsonia is a 3-season performer. From May through November, this native plant is a star.

The overture starts in mid-spring when shiny green leaves emerge wrapped around deep blue flower buds. The buds ride along as the leafy stalks rise to a height of 30 to 40 inches. Soon, the real show begins as the pale blue stars that give the plant its common name open, attracting a huge variety of pollinators.

**The flowers rise with the growing stalks**

**Pale blue stars cover the plant by late May**

The second act lasts all summer long – four full months! Amsonia is a clump-forming perennial that functions almost like a shrub. In time, the plant expands slowly from the base, but does not spread easily either by rhizomes or seed. The glossy foliage looks fresh all summer, reaching about 3 feet tall and almost as wide, and mixes well in a garden border, or even in a meadow planting. The stems may be cut back a bit after flowering to keep the plant’s compact form, or allowed to arch out in a looser shape.

*Amsonia tabernaemontana* at the New York Botanical Garden paired with *Zizia aurea* for a dazzling native combo

**Amsonia in the foreground with meadow plants in mid-summer**

In Act Three, Amsonia turns bright yellow, and the fall color lasts for weeks! It looks great combined with evergreens and fall berries, or mixed with contrasting foliage colors. The plant goes dormant and dies back to the ground in winter after 7 months of extraordinary performance.

**In November, Amsonia’s brilliant yellow contrasts with the purple foliage of Ninebark (*Physocarpus opulifolius*) at the Nature Center**

Native to moist woodland edges, and along streams and ponds from New York to Florida and west to Texas and Illinois, Eastern Bluestar is happy in Zones 3 through 9. Though its natural habitats are moist areas with well-drained soil, it is quite drought tolerant once it is established, and is reported to tolerate clay as well. It prefers full sun in the northern part of its range, but appreciates some afternoon shade in warmer regions.

Young plants may take a few seasons to get established, but Amsonia is a long-lived perennial. After a few years, the base of the plant becomes quite woody and difficult to divide, but left alone, it comes back year after year for a decade or more. And Amsonia is pest resistant – it has white latex sap that deer and other critters avoid. Gardeners with latex allergies may also wish to avoid it by wearing gloves.

It’s surprising that Eastern Bluestar isn’t better known among today’s gardeners since even its name dates back to Colonial times. Amsonia was named for a physician and amateur botanist, John Amson, who lived in Williamsburg, Virginia and once had a very famous patient. In 1758, George Washington was worried that he had contracted “consumption” (tuberculosis) during the French and Indian War. Fearing the worst, he visited Dr. Amson for advice. The good doctor reassured General Washington that he had nothing more than a common cold and was not going to die. To honor the esteemed Dr. Amson, the botanist John Clayton named the perennial flower “Amsonia” shortly thereafter.

If you go shopping for Amsonia tabernaemontana, you are likely to run into a few other Amsonias, and there can be some confusion here. A variety called Amsonia tabernaemontana var. salicifolia is native to the southeastern U.S. and has slightly narrower leaves than the northern species. It is often sold in nurseries in the Northeast, and is difficult to distinguish unless they are viewed side-by-side. There is no particular reason to avoid salicifolia unless you are in the Northeast and trying to plant strictly local native species.

**Amsonia ‘Blue Ice’ with taller Eastern Bluestar in the background**

A more perplexing issue is presented by Amsonia ‘Blue Ice,’ which is being widely sold and is becoming increasingly popular. A few years ago, a commercial grower with a greenhouse full of Amsonia tabernaemontana noticed some plants in the crowd with slightly larger and darker blue flowers and foliage more compact than the species. Horticulturists first classed ‘Blue Ice’ as a “selection,” a naturally-occurring variation with desirable characteristics that is then cultivated for sale by stem cuttings. Further study, however, has suggested that ‘Blue Ice’ is of “uncertain parentage,” which sounds a bit scandalous and could mean that ‘Blue Ice’ is a hybrid or an accidental introduction or something else altogether. At present, although the genetic mystery rules out the plant for purists, it really is a lovely garden perennial. ‘Blue Ice’ stays under 2 feet tall, which is great in smaller gardens.

There is another popular species of Amsonia called Amsonia hubrichtii or Threadleaf Bluestar, which is native only to Arkansas and Oklahoma. Although it is a fine garden plant, and is regularly sold outside its native range, you will maximize ecological benefits in your own area by planting the species that is native there.

For most of the Eastern US, and much of the Southcentral US, Amsonia tabernaemontana, our own Eastern Bluestar, is the true perennial star. Let the show begin!

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THIS BLOG IS AUTHORED WEEKLY BY CATHY LUDDEN, CONSERVATIONIST AND NATIVE PLANT EDUCATOR; AND BOARD MEMBER, GREENBURGH NATURE CENTER. FOLLOW CATHY ON INSTAGRAM FOR MORE PHOTOS AND GARDENING TIPS @CATHYLUDDEN.

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February 2, 2023February 2, 2023 greenburghnaturecenter Native Plants

After the Deluge

If you’ve ever enjoyed the sight of rain drops clinging to every leaf of a tree after a storm, you have observed one of the ways trees manage stormwater.

Forests intercept rainwater in the tree canopy, and slow its fall to the forest floor where it is absorbed and filtered before any excess gradually moves to streams. A forest can absorb at least 12 inches of precipitation per hour before surface water begins to move toward natural channels. In urban and suburban areas, with limited tree canopy, heavy rainfall hits the ground immediately and accumulates on impermeable surfaces, causing flooding.

**Frequent flooding makes stormwater management a top priority**

As rainstorms increase in frequency and intensity, flooded roads, neighborhoods, and basements have become critical problems for municipalities and residents. Storm water run-off from impermeable surfaces too often exceeds the capacity of urban and suburban systems. Engineered solutions to flood control are complicated, expensive, and controversial, so urban planners are increasingly considering “green infrastructure” – essentially, managing stormwater by changing how we landscape.

Trees not only remove carbon dioxide from the atmosphere, feed and shelter wildlife, and reduce energy demand for cooling, they are also the most cost-effective way to manage stormwater. Trees and related landscaping can keep excess water off of roadways, and out of your basement.

Trees manage stormwater in several critical ways. If you’ve ever sheltered from rain by moving under a tree, you’ve experienced “interception.” The tree canopy catches rain and holds raindrops on every leaf, twig, stem, and branch until they evaporate after the storm. A mature evergreen can intercept more than 4,000 gallons of rainwater in a year. In a suburban setting, a single deciduous tree intercepts 500 to 760 gallons per year. And a recent experiment demonstrated that even a small flowering tree can intercept 58 gallons of storm water during a ½ inch rain event, or about 67% of the rain that falls on its canopy. Intercepted stormwater never even touches the ground, so it cannot become run-off or cause flooding.

**Interception: even in winter, bare tree branches intercept stormwater and hold it for evaporation**

**The heavily-textured trunks of mature trees slow water down as it falls (“stemflow”) and hold rain until it evaporates**

Rainwater that is not intercepted by the canopy and hits the ground is called “throughfall.” Tree roots, which typically spread at least as wide as the tree canopy and are concentrated in the top 18 to 24 inches of soil, break up compacted soil so that more throughfall infiltrates and is absorbed by the ground. Ground water is then taken up by tree roots, transported to the leaves, and used in photosynthesis. That water ultimately is released back into the atmosphere in a process called “evapotranspiration.”

**Tree roots absorb water directly and also make soil more absorbent**

Trees consume or “transpire” an enormous amount of water. A single mature oak tree can transpire more than 40,000 gallons of water per year! Homeowners who take down mature trees may be shocked to realize that all of that water becomes run-off and a source of flooding when the tree is gone.

A tree surrounded by pavement or lawn takes up less water than a tree in the forest or a tree accompanied by other plants. Leaf litter, groundcovers, and understory plants dramatically increase the ability of the soil to absorb stormwater. By increasing organic matter and leaf surface under trees, both the amount of stormwater held, and the amount available to the tree for evapotranspiration, are increased significantly.

By contrast, lawn grass is barely more effective than pavement at reducing stormwater run-off. The roots of turf grass are only about 2 inches deep and do not retain much water. Mowing, removing lawn clippings, and using leaf blowers all have the effect of compacting lawn and reducing organic matter in the soil, further reducing its ability to take up water. Automatic irrigation systems, programmed to top-water lawn every couple of days without regard to rainfall, add to run-off problems.

**Lawn grass is not effective for stormwater control**

**The force of stormwater run-off on lawn is even enough to erode paving**

Worse, in most communities, storm drains do not channel run-off into sewage treatment facilities, but directly into local waterways, so the chemical fertilizers and pesticides typically applied to lawns are transported by stormwater run-off to our waterways. Pesticides, applied to lawn annually at 10 times the rate used by farmers, are a leading source of water pollution, contaminating groundwater, freshwater streams, rivers, and coastal waters. Lawn fertilizer, washed into storm drains, causes algae blooms and excessive weed growth in waterways.

**Storm drains route stormwater directly into streams, rivers, lakes, and the ocean**

**Stormwater run-off carries toxic pesticides from lawns**

Suburban residents can make their yards into “green infrastructure” by reducing lawn and planting densely with native trees and other plants. Parking lots, road medians, church and school grounds, apartment complexes, and any place with lawn or paved surfaces can be added to green infrastructure by planting native trees and landscape plants wherever possible. The best way to prevent stormwater run-off from flooding your basement, blocking your street, and reaching our rivers is to capture it in your own yard with the beautiful trees and plants native to our area.