native plants Archives - Page 5 of 14 - Nature Center at Greenburgh

December 6, 2023February 12, 2025 Cathy Ludden Around the Grounds, Native Plants

Mighty Arborvitae

Arborvitae gets no respect.

Though Arborvitae (Thuja occidentalis) may be the most-planted tree in suburban America, it has been given a diminished role unworthy of this majestic native tree. Planted by the thousands along property lines by developers, builders, and landscapers, rows of crowded Arborvitae trees, standing shoulder to shoulder, have become the de-facto fences of suburbia.

A typical builder installation of Arborvitae

Without room to spread their branches or reach their natural height, Arborvitae is often topped and heavily pruned to form hedges. They handle this assignment very well, but Arborvitae can do so much more!

If you’ve only seen Arborvitae used as a hedge, it may surprise you to learn that in its natural habitat, it can grow 50 to 60 feet tall and live for hundreds of years! In fact, the largest known specimen is over 100 feet tall and more than 40 feet wide at the crown. The oldest living Arborvitae is thought to have germinated from seed in 952 A.D., and is now 1,071 years old! Based on ring counts on dead trees, there are verified specimens of Arborvitae that lived to be over 1,800 years old.

An ancient stand of Arborvitae on cliffs overlooking
Northern Lake Michigan
*Photo: C.J. Earle*

Arborvitae is one of the common names for Thuja occidentalis and means “tree of life” in Latin. It was named by the French sea captain, Jacques Cartier, when he was exploring Canada in 1536. After months at sea, Cartier’s crew, including two young members of the Huron native tribe who had been sailing with them, were all suffering from scurvy. On the way up the St. Lawrence River, Cartier dropped the two young men at their home village. When he later returned, he was astonished to find the two Hurons fully recovered from all symptoms of scurvy while his French sailors were still suffering. He asked the Huron elders to teach him the cure, and they showed him how to make a medicine, a tea rich in Vitamin C, from the foliage of Thuja occidentalis. Cartier brought the life-saving plant back to France, making it the first North American tree introduced to Europe.

The native habitat of Thuja occidentalis is swamps, low woods, and forest edges from northern Canada south to New York and Connecticut and west to Michigan and Northern Indiana. It is an evergreen conifer, extremely cold hardy, and adapted to poor rocky soils all the way to the edge of the Canadian tundra. Sometimes called Northern White Cedar, Eastern White Cedar, or Swamp Cedar, Arborvitae is not a true cedar in the Cedrus family, none of which are native to North America. But the fragrance of its foliage and bark, and the usefulness of its wood, are similar.

Arborvitae often grows in very thin, poor soil in northern
North America and is adapted to extreme cold. This forest of
Arborvitae is at the brink of the Niagara Escarpment in Northern Wisconsin.
*Photo: C.J. Earle*

The foliage of Arborvitae is flat and scale-like and has a spicy fragrance when crushed. Native peoples used it not only for medicine but also used the fragrant foliage as insect-repellant bedding. They stripped the tree’s shredding bark to make rope and twine, and they found many uses for the rot-resistant wood, including canoe frames and roofing shingles.

Thuja occidentalis has significant value to wildlife. It is a favorite food of white-tailed deer, as suburban homeowners often discover to their dismay. Twigs and foliage of Arborvitae constitute as much as 10 to 25% of the winter diet of deer, who will browse it as high as they can reach. In northern forests, the tree also provides highly nutritious food for snowshoe hares, porcupines, red squirrels, and beavers. Many native birds find nesting sites in Arborvitae and insects to feed their young. The seeds are the preferred source of food for Pine Siskins, birds indigenous to the Northeastern US.

It is sadly ironic that one of the most-planted trees in suburbia is disappearing in the wild. Thuja occidentalis is listed as Threatened in Connecticut, Illinois, Kentucky, and Maryland and Endangered in Indiana, Massachusetts, and New Jersey. Development is the primary culprit as forests are cleared to make way for more suburban homes.

It is equally sad that the rows and rows of Arborvitae planted on suburban property lines are not nearly as valuable to wildlife as they should be. The most popular varieties of Arborvitae are cultivars or hybrids that offer little value to wildlife – other than deer. A cultivar called ‘Emerald Green’ Arborvitae was developed in the 1950s in Denmark, just in time for the rapid expansion of the US suburbs after WWII. It quickly became the ubiquitous hedge plant we see all around us. In a tight hedge, and with limited biological diversity due to clonal reproduction by nurseries, its value to insects and birds is limited.

Another Arborvitae popular with builders is a hybrid called ‘Green Giant,’ which is a cross between a species indigenous to the Pacific Northwest and a Japanese species. As a hybrid between two non-natives, ‘Green Giant’ has very little value to insects or birds in this part of the country. If you can find the straight species of Thuja occidentalis (without a cultivar name), plant that. If not, ‘Emerald Green’ is a better choice than ‘Green Giant.’

Thuja occidentalis is an amazing tree. It deserves to be more than a fence! Given enough room to take its natural form, Arborvitae merits a starring role in suburban landscapes.

Growing the way nature intended, Arborvitae takes its
rightful place with Oaks, White Pines, and Junipers in
Northeastern landscapes

In our last blog post [Privacy Without “O-fence“], we urged homeowners to diversify their hedges and privacy screens by planting a mix of native trees and shrubs to increase habitat and biodiversity. Too much of any one plant becomes a mono-culture, limiting resources for wildlife. Unfortunately, that is what has happened to this magnificent native tree.

Don’t limit Arborvitae to this poor fate

Think of Arborvitae as an easy-care, long-lived, medium-sized, native, hardy evergreen that will enhance your landscape as part of a diverse planting of trees, shrubs, and perennials. You won’t be sorry!

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.

November 15, 2023February 12, 2025 Cathy Ludden 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.

November 2, 2023February 12, 2025 Cathy Ludden 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.

June 1, 2023February 12, 2025 Cathy Ludden 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.

April 6, 2023February 14, 2025 Cathy Ludden 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!