Stream Monitoring Volunteers Track the Health of Arlington’s Streams

Text by Shay Pratt; photos by Colleen O’Hara

How can you tell if a stream is healthy? One of the best ways is to look at the tiny organisms that live in it. The flies, larvae, and worms found there can tell the story of a stream’s overall health, if you know how to read them.

Many types of spineless underwater organisms, known as benthic macroinvertebrates, live in the silt and pebbles of a Virginia stream bottom. Arlington County has an illustrated guide to about 20 of them found locally (adapted from the Izaak Walton League’s Virginia Save Our Streams site.)

Some are hardier than others when it comes to tolerating pollution, heavy stormwater, heat and other pressures. For example, flatworms and black flies are tougher than mayflies and caddisflies. So, you could expect to find flatworms just about anywhere you look, even in streams that aren’t very healthy, because they can tolerate tough conditions. In contrast, when you find a casemaker caddisfly, you know the stream quality must be pretty high.

By tracking the stream bug populations across time, Arlington County staff can assess the effectiveness of pollution prevention practices and identify new problems. That’s why the County’s Department of Environmental Services coordinates regular stream monitoring at 10 stream sites, including Donaldson Run, Gulf Branch, and multiple sections of Four Mile Run,  with the assistance of ARMN volunteers who are trained to methodically collect and analyze macroinvertebrates. 

Macroinvertebrates make for ideal test subjects because they don’t move much and they’re readily found under rocks and stones. They can be scooped up with nets, identified with magnification devices like loupes, and returned to the water. 

I learned all this one day in May, when I met other ARMN members at a picnic pavilion at Lubber Run park to collect and analyze samples. We split into teams of two to collect samples at designated spots along the stream, targeting shallow, rocky areas with fast-moving, oxygen-rich water—great habitat for macroinvertebrates. 

Two people stand in a stream in rubber boots. One person holds a net on a wooden pole while a sceond bends over and holds a rock in her hands.
Volunteers collecting mcroinvertebrate samples at Gulf Branch stream monitoring (analogous to the collections at Lubber Run).

My partner, Hutch Brown, a long-time volunteer who helps lead this monitoring group, dipped a long-handled net  into the stream. I stood just upstream, picked up a few stones and pebbles from below the water, and gently rubbed them on all sides, loosening debris and any bugs that were living there. They floated down the water and into Hutch’s waiting net. I then scraped the silty floor with a tool shaped like a garden fork to release any macroinvertebrates living there. We carefully rinsed the contents of the net into a white plastic tub, then set off to repeat the process until our group sampled 10 total locations. 

When all ten samples were collected, it was time to identify our findings. We carried our tub over to a picnic table strewn with sampling tools, ice cube trays, petri dishes, and microscopes. Using a shallow, white tray, I collected a sample of water from the collection tub and scanned its contents. 

A table covered with ice cube trays, identification sheets, and
Identification sheets and analysis forms used to document collection results.

Within seconds, I saw movement. A faint yellow, hair-like organism only a few millimeters long twitched and spasmed. Elsewhere, a dark shape contracted and elongated on top of a water-logged maple leaf. I scooped up each critter with a pipette and plastic spoon, and transferred it to its own well in an ice cube tray. Using a loupe and a macroinvertebrate guide, I worked with the trained identifiers in our group to identify each one. Meanwhile, Stephanie Martin, another team leader, documented everything for the County.

Macroinvertebrates are easy to identify with basic magnification and practice. Most stream bugs have telltale physical characteristics. Mayflies exhibit 2-3 hair-like tails. Flatworms have triangular heads and a pronounced, cross-eyed look. Black flies look like mini-bowling pins, with a sucker on one end that they use to attach to surfaces. Our group made quick work identifying over 100 organisms. 

In our survey of Lubber Run, we found mostly organisms that can tolerate poor to fair conditions—flatworms, black flies, a few aquatic worms, and lots and lots of midges. We also found some small minnow mayflies, which are much less tolerant of pollution, and indicate good riffle habitat found in the monitoring reach. These results confirmed that Lubber Run, like many of Arlington’s streams, is overall in fair condition. 

Of all of Arlington’s stream monitoring sites, Lubber Run’s watershed has the most hard surfaces, with about half of its land covered with roads, roofs, parking lots, and other impervious surfaces. When a stream’s drainage area is more than 10% impervious cover, it is considered to be impacted as an urban stream. Arlington’s streams reached that development milestone decades ago, as land that once absorbed rainwater was developed. Over 40 percent of Arlington land is impervious to water, so the streams channel a lot of water after storms. That stormwater scours out the homes of many invertebrates and often carries pollution and sediment that impact habitat. 

There are no easy fixes for these problems, but Arlington County is paying attention to the health of its streams—working to install Green Street rain gardens to capture rain runoff, reduce stream erosion, and educate the community about how we can all help prevent stream pollution. Data collected by volunteer stream monitors can make the case for intervention and track changes over time. 

Lily Whitesell, who coordinates stream monitoring as Arlington County’s Stormwater Outreach Specialist, said the ongoing work has documented seasonal patterns (life cycles of the macro invertebrates) and patterns of disturbance and recovery. Longer term trends have been stable over time.

“We want to help our streams be as healthy as they can be, given our urban watersheds,” Whitesell said. “It’s good for our benthic macroinvertebrates, for the fish that rely on them, for the overall diversity of our local aquatic and terrestrial ecological communities, for the people that enjoy, appreciate, and rely on our streams, the Potomac River, and Chesapeake Bay.”

For more information:

Teaching Children About Nature Through the Magic of a Loupe

Text and photos by Eric Weyer

Nature is a never-ending source of wonder, offering an abundance of intricate details, some so tiny they can barely be seen with the naked eye. That makes “loupes” (or hand lenses) one of the most important tools in any naturalist’s arsenal. 

During a recent training exercise for ARMN volunteers learning to teach young people about nature, I also saw what a powerful tool a loupe can be in a child’s hand.

A loupe is essentially a super magnifying glass that allows users to see small details up close and personal. Before I became a member of the Arlington Regional Master Naturalists in 2021, I didn’t know what a loupe was. 

Photo of a loupe
Loupe (hand lens).

My first use of loupes was practical. As a volunteer stream monitor for Arlington County, I used them to identify the macroinvertebrates that live in our streams. Telling the difference between broad-winged and narrow-winged damselfly larvae is tricky without magnification. 

However, it wasn’t until early April, during a training with Bobbi Farley and Serenella Linares, that I truly learned what a world of wonder loupes can open.

The goal was to teach volunteers with an ARMN after-school program called “Nature Core Outdoors” some tips and tricks for interpreting nature to children. Nature Core is a partnership between ARMN and the Arlington Housing Corporation (AHC Inc.) that aims to introduce elementary-age residents in AHC’s after-school program to nature. The program is led by Alison Sheahan and Romana Campos, and includes volunteers from ARMN and other local nature groups including Virginia’s Extension Master Gardeners and Tree Stewards of Arlington and Alexandria.

Volunteers commit to teaching six weekly one-hour after-school sessions, with the goal of sparking joy and wonder in the children for the nature living in their own backyard.

Bobbi, a naturalist at Long Branch Nature Center in Arlington, kicked off the session by describing an insect lesson she teaches to kids. She stopped throughout to explain techniques she uses to keep the children’s attention, such as call-and-response shouts or claps. She showed how to engage children with different learning styles by varying her questioning techniques—asking for a shout or a raised hand or directing a question to a specific person. And she shared some silly, interesting facts. (I believe poop came up at least once.) 

Serenella, a Park Naturalist at Mt. Rainier Nature Center in Maryland, then took us outside for another example lesson. She gave us a set of loupes and told us we had five minutes to find something interesting to discuss with the group. 

Being an enterprising fellow, I took out my phone and snapped a few pictures of a beetle crawling on an American Hornbeam (Carpinus carolinia) leaf. Others wandered around the area outside the nature center, looking at flowers, leaves, even the lichens growing on a branch by the trail.

After five minutes were up, I was the first to show my photo to the group. Everybody oohed and ahhed when they noticed the little bits of pollen stuck to the beetle’s elytra (forewings) and legs, an example of pollination up close! We shared a few other findings, then reluctantly returned our loupes to Serenella and headed back inside, where she used this experience to teach us some more child-focused interpretation and group management techniques.

I was inspired by Serenella’s lesson. If this activity evoked such joy in us adults, I could only imagine the wonder it would create with our group of around 20 eager-to-learn 8-to-10-year-olds at the Woodbury Park Apartments in Arlington.

In our first lesson with them, we had spent a long time looking at seeds with only our eyes. I knew how amazing those seeds would look under 30x magnification!

At the next class, I showed up with 32 loupes I had purchased online. From the moment I told the students, “You can look through these at small things like the seeds we observed last week,” they started running off in search of cool things to look at. They were so entranced that I, along with the other Woodbury Park volunteers Barbara Raizen, Eileen Miller, and Liz Macklin, decided to forget about our planned lesson and join them.

We spent about 15 minutes marveling at how different all the little things we see in everyday life look when blown up. The first thing we studied was a dandelion, noticing how its deep yellow bracts looked like those on other flowers nearby. Then we looked at some leaf galls. We decided that the teardrop-shaped green and purple galls were “nature’s Hershey Kisses.” The others we couldn’t quite agree on names for—alien spaceships and Alice in Wonderland were the top votes.

Later we gave up our loupes for our final event, a bird scavenger hunt. Liz highlighted some common birds in the area and we split into small groups to start our search, stopping every fifteen seconds or so to observe something new. Whether a bird or a bug, it was always a perfect thing to look at with our loupes. We even found a skull that we were able to identify as a rabbit’s skull.

At the end of the lesson, we could see the excitement in the children’s faces as they talked about everything they had discovered. Seeing their enthusiasm made us all feel like we had accomplished something meaningful, thanks to fabulous leaders and teachers—and a few dozen loupes. 

Photo of a drawing done by a child.
Child’s drawing of a loupe and the wonders that can be viewed through it.

The Call of the Wild—Knowing When an Animal Needs Our Help  

By Colleen O’Hara

This is the time of year when baby animals make their entrance into the world, and often times, into our hearts. Who can resist a fluffy baby bunny? Or a sweet, speckled fawn?  Very often we see baby animals on their own in the wild and wonder: Does it need help? Should I intervene? Or perhaps you’ve come across an injured animal.  What should I do and who should I call?

In Northern Virginia, there are two main resources to turn to for help and advice when dealing with wild animals. 

The all-volunteer Wildlife Rescue League receives on average 3,000 calls to its wildlife assistance helpline (703-440-0800) every year. The non-profit supports a network of licensed wildlife rehabilitators in Northern Virginia who help and care for hundreds of animals that they receive every year.

The Animal Welfare League of Arlington is part of the County’s Animal Control Department (703-931-9241). It responded to over 4,000 calls last year regarding pets and wildlife, including sick and injured animals. Over 1,000 animals went through its Wildlife Resource Center, which assesses injured, orphaned, or sick wildlife and transfers them to licensed rehabbers. 

When Should You Intervene?

Sometimes it’s obvious when an animal needs our help, and sometimes it is not. 

According to the Wildlife Rescue League, an animal needs help if it shows signs of flies, maggots, or worms, was caught by a dog, cat, or other animal, has a wound, is a baby and its parents are dead or separated and cannot be reunited, has suffered trauma such as being hit by a car or fallen from a high nest, is very cold and weak, is unable to move, or is not fully feathered or furred. 

However, in some cases, well-meaning citizens think an animal needs assistance, when it actually doesn’t, said Carolyn Wilder, the Wildlife Rescue League’s Chair of the Rehabilitator Committee, and Co-Chair of the Education Committee. For instance, baby cottontails and fawns are typically left unattended for most of the day by their parents, and fully-feathered baby birds on the ground are fledglings and are fine on their own.

“They do not need our help,” Wilder said. “They are learning to fly and they will continue to be fed by mom and dad.” Sometimes a fledgling will lean on one wing and it appears as if it is injured, but it is actually using it as a “training wheel”, she said. 

Raptors are an exception, however. A juvenile eagle or owlet that is on the ground and unable to get back to a tree, will need rescuing because their parents will not feed them if they are on the ground. Most raptors are transferred to Blue Ridge Wildlife Center for rehabilitation, Wilder said. 

Other Guidelines and Tips  

If you find an injured bird, or you witness a bird striking a window, place it in a box in a quiet location and call for advice. Do not give it any food or water unless a rehabber tells you to. Typically, a bird does not survive a window strike, even if sent to a rehabber, Wilder said. 

Photo of a baby robin in a garden planter.
Robin photo by Josie Weiss on

If a baby bird falls out of a nest, try to return it to the nest or make a nest out of a small plastic bowl and place it high up on the tree. The bird will not be rejected by the parents just because it has been touched. A bird egg on the ground cannot be saved, however. 

Photo of a baby racoon.
Raccoon photo by Thomas Dils on

If a baby squirrel falls out of the nest, keep it warm in a box lined with a towel or heated rice sock, and play baby squirrel sounds on your phone (you can find this online). The mother will typically come down, retrieve the baby and return it to the nest. Raccoon babies that have fallen out of the nest will usually be rescued by the mother at night. It’s a good idea to put it in a box near where it was found, such as the base of a tree. 

If you see a fox kit during the day, they are often just playing and exploring, while adult foxes are often looking for food or a new den. If a kit becomes separated from the adult, the adult will return to get it if it does not have a human scent on it, according to the Wildlife Rescue League. If the kit has been alone for two hours, then it’s time to call for help. 

If you happen to find a baby opossum on the ground, it’s time to call a rehabber whether it is injured or not. The mother opossum carries her babies on her back once they emerge from the pouch. She is transient, so if a baby falls off en route and she doesn’t notice, the baby can’t survive on its own. 

If you come across a baby turtle, leave it alone. When turtles fully hatch, they are able to survive on their own. However, if you find a turtle that is in a precarious location such as in the middle of a road, move the turtle to a safe spot in the direction it was headed. 

Legal Dos and Don’ts

In Virginia, it is illegal to take, possess, buy, sell, or liberate wildlife, or destroy bird nests that have eggs in them, with the exception of English sparrows (aka house sparrows), starlings and pigeons, which are considered non-native invasives. Rehabbers do not treat these birds, either. 

In addition, only a licensed rehabber is legally permitted to treat a fox with mange in Virginia.

Typically, if a fawn is crying, begging or showing other signs of distress, it would need help. However, a law that took effect May 1, 2023 in Arlington, Fairfax, and several other counties prevents any rehabber from taking in a baby deer because of the potential of spreading Chronic Wasting Disease, Wilder said. More information about Chronic Wasting Disease can be found at: Wildlife Center of Virginia. Note also that adult deer cannot be rehabilitated anywhere in Virginia.

Citizens can’t kill or trap wildlife without a license, either, although they can trap wildlife on their own property—they are just not allowed to relocate it. They can’t transport wildlife across state lines unless it’s a bird, and it’s illegal to keep wildlife as pets. However, a Good Samaritan law allows citizens to capture and transport wildlife to receive care, provided they have received permission from a veterinarian or a rehabber first, Wilder said.

The Wildlife Rescue League and the Animal Welfare League of Arlington welcome support for their wildlife rescue and rehabilitation efforts, Wilder said. Consider becoming a wildlife rehabilitator, care provider, or transporter!   

Join the 2023 City Nature Challenge, April 28-May 1!

by Caroline Haynes

Mark your calendars for April 28 through May 1 to participate in the 2023 City Nature Challenge (CNC). Join your friends, family, and neighbors in this fun annual nature event.

What is the City Nature Challenge?

The CNC encourages interest in discovering urban nature by having individuals observe, record, and identify the nature around them. It celebrates and supports two vital functions of citizen science: bringing members of the community together to enhance their appreciation of nature, and providing scientists with valuable data on biodiversity that can help guide the understanding and preservation of our natural resources. The event started out as a friendly competition between Los Angeles and San Francisco in 2016 to document urban nature using iNaturalist, a free app and website that allows individuals to easily upload, share, and identify species. It has expanded to over 450 cities in 40 countries this year. ARMN is helping to organize participation in the “City Nature Challenge DC,” encompassing the entire DC metro area, and then some: 14 counties in Virginia, 5 counties in Maryland and Jefferson County in West Virginia. We urge all people in these areas to participate. It’s easy to do and fun for folks of all ages!

Plant NOVA Natives video on the 2023 City Nature Challenge.

ARMN has participated in the challenge since 2017. In 2022, out of the world-wide competition, the DC metropolitan area came in first in the number of identifiers, second in the number of observers, fifth in the number of observations, and seventh in the number of species identified. We’re hoping to build on that incredible record again this year!

Who can participate and where?

ARMN is supporting a wide variety of observation events in Arlington, Alexandria, Falls Church and Fairfax County (link to events provided below). There are plenty of locations and times to choose from if you want to work with a group, or you can just go out and explore and make observation in your favorite park in any of the above-noted areas. Invite your friends and families and neighbors to become citizen scientists and participate; all ages and levels of expertise are welcome. The more eyes the better on the ground, in shrubs, trees, streams, the sky—in other words, everywhere around you in nature. Join the fun, and contribute to the collection of data, to see which “city” can engage the most participants, make the most observations and identify the most species.

Where to learn more and sign up

Logo for California Academy of Sciences and Natural History Museum of LA County

Phenology: Timing Nature’s Clock  

by Rosemary Jann

Spring came unusually early to the Southeast and Mid-Atlantic this year, including here in Arlington. Many of us have been delighted to see trees, shrubs, and plants emerging early all over our area because of our unseasonably warm winter. 

For scientists who study phenology, these seasonal variations hold a more specific significance.

Phenology studies the timing of recurring life cycle phases in plants and animals and their relationship to weather and climate: when leaf or flower buds break, when insects hatch, when birds start to nest or fruit starts to form. Maintained over multiple years, phenological data can contribute to prediction models that influence decision-making in many fields.

Phenological trends can help determine the best time to plant crops or to treat for insects that damage them. They can predict when flowers are likely to bloom and thus when allergy season is likely to peak, or the best dates for scheduling events like Washington’s Cherry Blossom Festival. Phenological data can help scientists identify the drivers of environmental change and project future trends.

One of the most significant uses for phenological data lies in demonstrating the effects of climate change. “Changes in phenological events like flowering and animal migration are among the most sensitive biological responses to climate change,” according to the USA National Phenology Network (NPN). 

Of particular concern is accumulating evidence that rapid climate change is producing mismatches in phenological events that have negative impacts on animals. The chart below, for instance, depicts what happens when caterpillars hatch before migrating birds are ready to feed the nestlings that need those caterpillars to survive. 

From:“Migratory bird phenology,” by Nadiah Pardede Kristensen.

The NPN was established in 2007 to collect, store, collate, and share phenological data. Since then, it has accumulated more than 30 million individual observation records from over 15 million observers, many of them citizen scientist volunteers who log their data through the NPN’s online tool, Nature’s Notebook. The NPN database currently includes records for more than 1750 species of plants and animals found across the United States.

Volunteer observers for plants follow the NPN’s list of standardized life cycle events or “phenophases” for specific individual specimens, like breaking leaf buds for a tree or open flowers on a perennial. The goal of observation is not necessarily to establish the exact date that buds break but rather through regular weekly monitoring over multiple years to help track trends in the overall timing of onset, duration, and intensity of phenophases in particular species and places.  

In 2022, a team of 10 ARMN members began our own multiyear citizen science project to study local phenology at three sites: Arlington Central Library, Marcey Road Park, and Potomac Overlook Regional Park. The project selected plant species from some of Nature’s Notebook’s special regional campaigns in order to maximize the usefulness of our data for scientists and decision makers. Nature’s Notebook’s “Green Wave” campaign targets leaf break and color change in oaks, maples, and poplars to help model the ways climate change is affecting deciduous trees. Also, “Nectar Connectors” studies the availability of nectar for monarch butterflies and other pollinator insects by tracking flower bloom in a selection of common nectar plants like the milkweeds, cardinal flowers, and buttonbushes that the phenology project is monitoring. The beauty of the Eastern redbud tree has made it a ubiquitous landscaping plant across the eastern United States. The new  “Redbud Phenology Project” will track flowering and fruiting to determine the effects of latitude, elevation, and climate on redbud phenology. 

In addition to contributing to these national campaigns, the ARMN phenology project also hopes to produce information to educate our local constituencies about the effects of climate change. Watch this space for more information about our results later this year.

Acer rubrum (red maple) flowers by Celia Cuomo, CC-BY-NC-SA; Nature’s Notebook data sheet for deciduous tree or shrub.

The National Phenology Network welcomes volunteer observers, and your own front yard or local park could become an observation site. Nature’s Notebook provides all the information you need to get started, including a “how to observe” course. Sign up for an account, register your site, choose your plants or animals, and you’re ready to start monitoring through their mobile phone app or the Nature’s Notebook website. Join the thousands of citizen scientists who are advancing our understanding of climate change through the National Phenology Network!

ARMN Winter Book Share: Food for the Body, Mind, and Spirit!

Text by Lori Bowes; photos by Rodney Olsen

Once or twice a year for the past decade, ARMN members and friends who enjoy nature writings meet at a local restaurant for a Book Share event. In February, we met in the Ballston Quarter food court where everyone could select their own lunch. Most people opted to patronize Maizal, a Latin street food vendor that “serves up a fresh take on one of South America’s most coveted street foods, the arepa.” The savory food was a perfect accompaniment to our conversation about enriching books. 

Photo shows a group of volunteers around a table piled with books.
Marion Flynn (l), Lori Bowes (r), and other book lovers enjoy discussing nature-related books at the ARMN Winter Book Share.

The event proved a nice opportunity to reconnect with local naturalist friends and catch up on one another’s projects, while being enticed by some new publications. The materials that people shared were diverse, including articles, science essays, nonfiction environmental books, historical nature fiction and even a podcast.

Photo shows three volunteers. One holds up a book while two others look on.
Joanne Hutton (l) listened as her husband, Powell Hutton (r), talks about the impactful book, The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth’s Past Mass Extinctions.

For example, Powell Hutton talked about The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth’s Past Mass Extinctions, a 2017 book by science journalist Peter Brannan about the current sixth mass extinction in the context of Earth’s past mass extinctions and the evidence for their causes.

Photo of a volunteer holding up a book
Margaret Chatham discusses the book, Journal of Garden History: An International Quarterly 16(1) January-March 1996: Bartram’s Garden Catalogue of North American Plants, 1783.

Margaret Chatham shared her impressions of a wonderful classic: Journal of Garden History: An International Quarterly 16(1) January-March 1996: Bartram’s Garden Catalogue of North American Plants, 1783.

Jill Barker introduced the historical fiction book, The Island of Missing Trees by novelist, Elif Shafak. It’s described in a Harvard Review as including a “prominent fig-tree narrator, who brings her own arboreal expertise into the story,” an ideal vantage point for Master Naturalists.

And I recommended a podcast entitled, “The Science of Birds: A lighthearted exploration of bird biology.” With more than 70 episodes available to date, it promises a fascinating listening and learning experience about nearly all aspects of bird biology.

Does a book share event sound interesting to you? Keep an eye on the ARMN list-serv or subscribe to the ARMN newsletter to find out when the next one will take place. Anyone with an interest in nature is welcome. We hope to see you at a future Book Share event!

The works shared during the February 2023 meetup included:

  • Teaching the Trees, Lessons from the Forest, by Joan Maloof, 2010
  • Oaxaca Journal, by Oliver Sacks, 2012
  • Journal of Garden History: An International Quarterly 16(1) January-March 1996: Bartram’s Garden Catalogue of North American Plants, 1783
  • The Soul of an Octopus: A Surprising Exploration into the World of Consciousness, by Sy Montgomery, 2015
  • The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth’s Past Mass Extinctions, by Peter Brannan, 2017.
  • Entangled Life: How Fungi Make our Worlds, Change our Minds, and Shape our Futures, by Merlin Sheldrake, 2020
  • The Invention of Nature: Alexander von Humboldt’s New World, by Andrea Wulf, 2015
  • An Immense World: How Animal Senses Reveal the Hidden Realms Around Us, by Ed Yong, 2022
  • I Contain Multitudes: the Microbes Within Us and a Grander View of Life, by Ed Yong, 2016
  • “Smart Plants” by David Haskell in Scientific American,  
  • Fen, Bog, and Swamp: A Short History of Peatland Destruction and its Role in Climate Change, by Annie Prioux, 2022
  • Seed to Seed, by Nicholas Harberd, 2008
  • Anything written by Bernd Heinrich
  • The Shepherd’s Life: Modern Dispatches from an Ancient Landscape, by James Rebanks, 2015
  • The Rise and Reign of the Mammals: A New History, from the Shadow of the Dinosaurs to Us, by Steve Brusatte, 2022
  • Saving the Wild South: The Fight for Native Plants on the Brink of Extinction, by Georganne Eubanks, 2021
  • Bird Brother: A Falconer’s Journey and the Healing Power of Wildlife, by Rodney Stotts, 2022
  • Ways of Being: Animals, Plants, Machines: The Search for Planetary Intelligence, by James Bridle, 2022
  • Ministry for the Future, a novel by Kim Stanley Robinson, 2020
  • The Island of Missing Trees, a novel byt Elif Shafak, 2021
  • The podcast, “The Science of Birds: A lighthearted exploration of bird biology.”

Fighting a “New” Non-Native Invasive in Town: Reports from the Front Line on Removing Italian Arum

Text by Kit Britton; photos by Jim Bly, unless otherwise noted. 

The February 26 Italian arum eradication event at the grounds of Culpepper Garden senior living community was the kickoff of a stewardship activity to last one year. A plant that was likely spread to the site as an escaped houseplant, in the root ball of a purchased plant, or by bird transmission of seed has turned into an ecological nightmare.

What is Italian Arum and Why is it a Problem?

Italian arum (Arum italica) is an ornamental plant that was brought to North America because of its attractive winter foliage and orange berries. It has been listed as a “dirty dozen” plant in Virginia can spread quickly to nearby areas and can outcompete native plants. It can be spread further by birds that eat and disperse its seeds. Arum has orange-red berries that grow in oblong clusters and can be toxic to both humans and wildlife. Its flowers emit an unpleasant odor, and its oils are a known skin irritant. Even with all these negatives, it is still commonly sold in the horticulture trade as both a houseplant and a landscaping plant.

Photo showing Italian arum spreading across the forest floor.
Italian arum infestation in an Arlington backyard. Photo by Brooke Alexander.

Sightings of this plant in Arlington vary. Some are found on the margins of parks near houses and gardens and in backyards and neighborhood vacant lots, but they also appear in parks far from potential backyard origination points. Unfortunately, once Italian arum takes root, it can become quite dense. 

At Culpepper Garden, staff and residents were horrified to discover the potential damage this spreading invasive could do to this iconic 5-acre site. As a resident of the community and ARMN member, I suggested that we contact Jennifer Soles, Invasive Species Coordinator of Arlington’s Department of Parks and Recreation. Once she investigated the situation, she developed a protocol for eradicating the Italian arum from the location.

Photo of two volunteers examining an arum plant before putting it into a bag.
Volunteers work together to extract and bag an arum plant.

At Culpepper Garden, the Italian arum plants were more widely spaced than in many places, making their removal easier. Using Jennifer Soles’ directions, we dug up each plant with its surrounding soil, lifted the whole mass carefully into bags, and marked the holes from which the plants had been removed with red flags for a one-year measurement of outcomes included in the project design. It took 11 volunteer Master Naturalists, community volunteers, and resident volunteers about three hours to dig up and bag 36 plants found in four distinct areas of infestation. 

Later, Culpepper Garden grounds maintenance staff picked up the tied bags and carefully transported them to the trash dumpster for treatment as trash (not compost, which could spread their seeds).

This project is coming at the right time because it may add information about control options at a time when Italian arum infestations are on the rise—not only at Culpepper Garden but in area private properties and public spaces where ARMN park stewards work. (Park stewards are Adopt-a-Park leaders who oversee volunteer stewardship work in Arlington, Alexandria, and Falls Church parks and engage with neighboring park communities.) And there is still time to dig up the plants prior to their 2023 seed production.

How Does the Italian Arum Spread?

Photo shows exposed tubers of the Arum plants.
Exposed tubers that show lateral root growth of Italian arum plants.

Arum italica has two methods by which it propagates and spreads. First, the above ground foliage grows from an underground tuber or bulb; the tubers propagate by forming multiple bulblets or daughter tubers, which separate and produce new stems. As the tubers spread laterally, Italian arum spreads. Sometimes, small plants can be eradicated by digging out all plant parts and tubers.  

The second method of propagation occurs when the plant flowers in the spring and summer and produces heavy seeds that drop onto the ground below or not far away. Wind cannot carry these seeds, but water flow can. And birds eat and spread the seeds.

Photo shows the light yellow flower of the Arum plant.
Arum flower head. Photo by Pedro Pinho, CC-BY-NC. (Arum berries are pictured above.)

The seeds themselves form a “transient” seed bank with less than one year of viability; not a “persistent” seed bank with seeds viable for more than one growing season.  Despite the transitory nature of the seeds, the next step in the reproductive cycle from seed is formation of a tuber that stays dormant for two years. So, there is effectively a three-year lurking danger from underground: one year as viable seeds and two years afterwards as dormant tubers. On the Culpepper site, seeds dropped by plants in summer 2022—as well as seeds up to two years older than that—can germinate plants now.

So, How Can We Get Rid of Italian Arum Once and For All?

Photo shows two volunteers working with shovels.
Volunteers use shovels to remove Italian arum plants and their surrounding soil.

In January, Master Naturalists exchanged strategies to eradicate Italian arum from their parks and neighborhoods, and after spirited discussion, the consensus was that digging and removing all plant material and more dirt than one might think necessary is needed to dispense with both dormant bulblets and the stubborn seedbank lurking in the soil. 

In addition, for resilient plants like this Italian arum, Master Naturalists wondered if chemical treatment would be an effective long-term solution. The problem is that only complicated chemical mixes may work, and these are beyond the reach of typical homeowners. This solution was also nixed by the Washington State Noxious Weed Control Board (a state where this invasive plant is rampant). There has been no consistently reported success with any chemical mix. With that, the Noxious Weed Control Board confirmed that manual methods including deep digging are the way to go. So, the Master Naturalists are sticking with manual removal, too.

The Plan for Culpepper Garden

We decided to monitor the holes left behind from which the arum was pulled and the broader infestation areas on a weekly basis and note any new growth. Italian arum plants found will be removed immediately. Weekly removals will ensure that we get the plants out when they’re very small. Removals at or near the holes will hopefully provide data to evaluate and refine the eradication protocol. The admittedly optimistic scenario of no regrowth in and around the holes would indicate that we successfully removed dormant seeds and tubers. Some regrowth but less than at a distance in the broader infestation areas could indicate that we need to dig deeper. Also, if the plant doesn’t appear at or near the holes but does show up at a distance in the broader infestation areas, perhaps we are dealing with bird transmission or other forms of transmission.

The project will end on Feb 16, 2024, when the one-year monitoring period is over, after which we will use the data we gathered to refine protocols for future Italian arum eradication. 

Normally, ARMN volunteers only work in parks or other natural areas rather than private properties. While Culpepper Garden is private property, it has been designated as “Private Property of Special Ecological Significance.”  As such, ARMN volunteers may work here on invasive plant removal projects.

Photo shows a volunteer smiling at the camera
Volunteers feeling optimistic as they remove arum at Culpepper Garden.

Restoring Nature by Whittling Away at Woodlawn Park’s Invasive Plants

Text and photos by Devin Reese, except as noted.

A volunteer is bending over by a creek.
ARMN Volunteer Becky Hamm looking for small invasives sprouting up.

I joined a group of volunteers recently who were getting ready to attack exotic invasive plants on the banks of Lubber Run stream. The site—Woodlawn Park—is a small park tucked into a residential neighborhood in Arlington. Perhaps its diminutive size explains how well its invasive plants are being addressed, or perhaps it should be credited to the enthusiasm and dedication of its volunteers.

Beth Kiser is the volunteer ARMN Park Steward for Woodlawn Park and the lead for the ARMN Park Stewards Program. (Park Stewards are Adopt-a-Park leaders who oversee volunteer stewardship work in Arlington, Alexandria, and Falls Church parks and engage with neighboring park communities.) Beth said that she is about five years into organizing volunteer work in Woodlawn Park and that, thanks to a cadre of regular monthly volunteers and support and coordination from Arlington County staff, the site has gradually transformed. 

Another neighborhood volunteer explains that “We’ve been working for a long time on removing the bush honeysuckle.” According to the Virginia Department of Conservation and Recreation, “Bush honeysuckles can rapidly invade and overtake a site, forming a dense shrub layer that interferes with
the life cycles of many native woody and herbaceous plants.” Today, the group is equipped with a Weed Wrench to wrest any bush honeysuckle (Lonicera spp.) out by the roots without disturbing the soil. Watching another volunteer tackle a different invasive plant, porcelain-berry vine (Ampelopsis brevipedunculata), a volunteer laments that, “It’s so evil. Porcelain-berry deserves more [removal] attention.” Like the bush honeysuckle, porcelain-berry can outcompete native plants for water and nutrients. 

One volunteer holds her phone out
Park Steward Beth Kiser showing volunteer Curt how to use the SEEK app.

Volunteer Curt is working to get the porcelain-berry vine out complete with its roots. “Wow, it does have a huge root. It’s going so far back. Is that normal for porcelain-berry?” As Curt remarks that he’s pretty new to this invasives work and needs people pointing stuff out, Beth shows him how to use the Seek app to help identify plants. The app is a companion to iNaturalist, the online social network of naturalists, citizen scientists, and biologists who create and share biodiversity information about plants, animals, and other organisms to help people learn about nature. However, Seek is designed to be more youth-friendly by including live AI-based identification using phone camera video as an input. Curt and Beth quickly corroborate that another plant he has removed is a type of privet.  

This is Curt’s first month of volunteering for naturalist habitat restoration projects, and he hopes to get to join the next ARMN training course. He has long been interested in the natural world and would love to improve his skills in identifying organisms, birds in particular. Curt also works as the Smithsonian’s National Museum of Natural History in the paleontology curatorial department. “I work with dead things at the Smithsonian,” he explains. So, this is his chance to work with living things. 

The spines of the black locust tree.

Becky Hamm is a member of the most recent ARMN cohort and volunteering at Woodlawn Park for the first time. Her inspiration to become a Master Naturalist came from living in a place with no outdoor space of her own during the pandemic. Her job in data analytics keeps her indoors. When she moved to a rental place with a yard, she wanted to create something other than a mowed patch; thus, began her exploration of native plants. Becky marvels at a native black locust tree (Robinia pseudoacacia) growing streamside, recognizing its distinctive paired spines, i.e., “big old thorns.”

A volunteer in a winter coat and cap holds a weed that he has pulled from the ground.
Volunteer Joao with a handful of invasive Chinese privet (Ligustrum sinense), another invasive import that can choke out native plants.

Meanwhile, one of Beth’s regular volunteers is working at the south end of the park. Joao lives a stone’s throw from where he’s removing invasives and has been interested in tending the park since the beginning of Beth’s stewardship program. He waxes poetic about how the program has boosted the number of “beautiful, wonderful birds that come and sing,” including an owl that he recently heard “mewing like a child.” He comes out in the evenings to enjoy nature at dusk. Joao explains that he grew up on Madeira Island, Portugal, in a setting with an abundance of colorful flowers. He returns regularly to Portugal, but also appreciates the Virginia nature right here in his front yard. 

Beth explains that regular, community volunteers like Joao have helped gradually change the park to a wilder space. “It’s looking pretty clean” of invasives, she says, “and I credit all those folks who’ve been coming for a few years now even during the pandemic,” as well as support from Arlington County staff, who provide input on invasive management approaches. Where resources permit, they also arrange for carefully targeted spot treatments of herbicides to address invasives that volunteers can’t remove by hand. This partnership has proven essential, she says, in having lasting impact in restoring the area’s natural spaces and keeping up volunteers’ engagement in the work without getting discouraged.

In the five years of her supporting the park and the ARMN Park Stewards program, Beth is most excited about the native species that pop their heads up through the leaf litter now that there is clear space for them to grow back from seedlings or from dormant seeds in the soil bed. Thanks to getting invasives out of the way, she now sees native plants like wild ageratum (Conoclinium coelestinum), asters (family Asteraceae), native black cherries (Prunus serotina.), hollies (Ilex spp.), tuliptrees (Liriodendron tulipifera), American sycamore (Platanus occidentalis), American persimmon (Diospyros virginiana), and a few oaks (family Quercus). The native plants in the park appear to be part of two distinct remnant ecological communities that Beth describes as “floodplain forest” and “possibly mesic mixed hardwood,” respectively, pointing to the floodplain area where there are American elms (Ulmus americana), boxelder (Acer negundo), and remnant green ash (Fraxinus pennsylvanica), which is amazing for this small patch of a park.

An up close photo of English ivy
English ivy (Hedera helix) on exposed tree roots.

In some harder-to-access areas in the park, invasives continue to take root. For example, English ivy blankets exposed tree roots in the steep slopes of Lubber Run that get less volunteer attention due to limited access. A volunteer says “Ivy is so evil. I don’t trust it. I always give personalities to the most invasive plants.” By her metric, we are wrestling with a lot of evil plant personalities as we pull, cut, and chop up. In the winter, with most of the plants not in their seeding stage, we can either chop them up and leave them on the ground to add to the valuable forest floor covering, or we can hang them up higher on branches. Beth talks about how people often remove the leaf duff (litter) from the ground, even though it harbors beneficial insects such as butterfly larvae and fireflies, microbes, and nutrients. Allowing the leaves to stay in place over winter can help these insects to thrive.

Serrated shovel that works well for extracting privets.

Eventually, ARMN volunteer Hal Cardwell climbs down into the stream valley with Beth’s specialized shovel (which she in turn had learned about from another neighborhood volunteer). Capitalizing on its serrated edges, he’s able to extract several well-anchored privets from the soil. A few slices and the privets are out!

An upclose photo of a weed pulled from the ground
Oriental False Hawksbeard plant removed with its roots.

Even as the group wraps up for the day, we find a few more opportunities for restoration. Curt spots a flowering plant on the streambank near where we started our work, and Beth excitedly says “Get it. That’s a Rose of Sharon with seed pods!” Indeed, this invasive’s fluffy brown flowers taunt us from their skinny stalks. Curt reaches down and gingerly pulls the Rose of Sharon (Hibiscus syriacus) out, careful to include the whole tap root. Right at our feet, Becky finds an errant Oriental False Hawksbeard plant (Youngia japonica) anchored to the ground. “It’s really aggressive,” says Beth, as Beth lays it—conquered—on a rock. 

Even at such a well-tended site, there are no shortage of opportunities for volunteers to battle invasives and improve its ecological quality through native plant regeneration. As we clean up, Beth tells us about the fireflies (Photinus pyralis)—an indicator of ecosystem health—that blink in the restored riparian vegetation along the stream during the warm months, and attract community members to gather and celebrate them together one night each June. The work today that helped to preserve a home for these beloved creatures was indeed well worth it.

Photo of a group of volunteers posing with a bucket and tools.
Volunteers after the day’s work. Photo by Beth Kiser.

Wildlife (All forms of life that are wild, including plants, animals, and microorganism – Natural Resources Service

Black Locust (Robinia pseudoacacia) Black locust, considered invasive in some states, is native to eastern North America from Pennsylvania to as far south as Georgia. When British colonists encountered the plant in 1607, they recognized its resemblance to Old World Locust and named it accordingly. A member of the pea family with pairs of round leaflets on spiny branches, black locusts improve soil quality by fixing nitrogen at their roots. The black locust produces fragrant white flowers with copious nectar that attracts native bee species, hummingbirds, and butterflies. Although toxic to some livestock, black locust provides habitat for native wildlife, including nesting songbirds and foraging deer. Learn more about black locust here.

The Grass Seeds, My Friend, Are Blowin’ In the Wind

Text and photos by Noreen Hannigan, unless otherwise noted.

Yes, grass seeds are blowin’ in the wind, but they’re not necessarily producing a pretty song! The list of non-native invasive grasses that escape cultivation from yards and gardens keeps growing. The 2022 edition of Plant Invaders of Mid-Atlantic Natural Areas, Field Guide by Jil M. Swearingen and Judith P. Fulton characterizes invasive plants as “an invading army” that can spread rapidly to take over natural ecosystems and be “difficult if not impossible to eradicate” once introduced and established over wide areas. 

What Kinds of Grasses are Considered Invasive and Why Is This a Problem?

Because many of the plants in local yards and for sale in garden centers evolved elsewhere, under different conditions, they no longer have the kind of competition to control their spread that they would have in their original setting. They therefore have the freedom to run amok away from their homes (like teenagers on spring break). They multiply rapidly and can displace native plants, form monocultures, and thereby eliminate sources of good-quality nutrition for our year-round and migrating wildlife. Some also release chemicals into the soil that inhibit the growth of other plants, or hybridize with native plants, which alters those plants’ attractive qualities for wildlife. These are just a few of many ways invasive plants degrade the ecosystem, which leads to populations of animals, birds, and insects (both in the young and adult phases) going into decline due to scarcity of food from the native plants on which they depend. This, in turn, robs the entire planet of biodiversity. Note that all of these plants are fine as long as they stay where they evolved. And in turn, some plants from our region have been introduced overseas and are invasive in other places for the same reasons the non-natives here are a problem. It’s all about keeping plants and wildlife where they evolved and not, as the saying goes, “moving puzzle pieces around.”  Ecosystems take millions of years to evolve and moving a plant halfway around the world in a day’s airplane ride happens way too fast for an ecosystem to adapt.  

Back to the newly revised Plant Invaders field guide, though, I noticed while I was thumbing through it that it includes almost double the number of invasive ornamental grasses and sedges than previous editions. One new entry in this field guide is Chinese fountain grass, Cenchrus purpurascens. (It actually goes by a couple of Latin names, including Pennisetum alopecuroides. And—no surprise—it goes by more than one common name, too, but more on that in a moment.) This non-native grass is widely available for gardeners, usually with no mention that it can escape gardens and invade natural areas, with detrimental consequences, so it’s important to have our antennas up when we are visiting garden shops.

I had an unexpected encounter with this escapee hiding on an inconspicuous section of the stream bank of Four Mile Run near Bon Air Park last fall. I had just come home from the Falls Church Farmers Market on a Saturday morning in late November and was about to enjoy a piece of warm spinach quiche and a cup of coffee when I got a text from my neighbor and fellow ARMN member, Mikki Atsatt, saying that she had spotted Chinese fountain grass, with its seed heads ready to fling themselves into the water and onto the wind, and said she was on her way to the park to do something about them. Mikki had contacted ARMN president, Phil Klingelhofer, and asked permission to go to Bon Air Park and deadhead these mischief makers ASAP. Not only did Phil approve, he grabbed his collecting pail, and joined in. More later on why she needed to ask permission to remove the seed heads in the park, and why anyone should do this before removing any plant material from a park or natural area.

I ate my quiche and drank my coffee faster than I intended and joined Mikki and Phil at the crime scene where the escapees were hiding. One personal “benefit” of my delay was that by the time I showed up, Mikki had figured out that the seed heads were so ripe that they could be easily stripped by hand, as opposed to having to be cut off. This was a great time saver. Nevertheless, it took about two hours to strip the seeds off that stand of fountain grass. Ninety nine percent of them went into our buckets to be emptied into the trash for disposal; however, it was impossible to prevent a few seeds from dropping onto the ground or getting stuck to our clothing. Ugh!

While the seed heads look soft and fluffy to the eye, according to the Vascular Plants of North Carolina website, the seeds are “notorious for their extremely strong and sharp spines which catch on clothing, fur, and skin alike.” Indeed, my clothing was covered with them when I left, so I can confirm how easily these seeds, which are like a grain and open after a hard freeze, can be spread not only by wind and water but by animals (including humans). Unfortunately, all we were able to do that Saturday morning was thwart the immediate spread, but every little bit helps. 

A photo of a black pant leg with many seeds sticking to the fabric
Seeds that hitched a ride on my pant leg from Bon Air Park (and removed in my shower to prevent them from spreading further).

What if You Already Have This Plant in Your Yard?

If you have Chinese fountain grass in your garden, consider removing it, or at least deadheading it every fall and dispose of the seeds in the trash before they break open. According to Jennifer Soles, Arlington Parks and Recreation’s Natural Resource Specialist, it has been found in numerous natural areas in the County, and once established, it is difficult to dig up. Ms. Soles said that the County is looking at strategies for controlling it in the future, and that she expects Chinese fountain grass to be added to future lists of invasive plants impacting our entire region. Meanwhile, until control methods can be employed, she said, removing the seed heads helps to slow the spread, so volunteer efforts are welcome.

Besides the clumps found in the Bon Air Park area, more was located along Four Mile Run in nearby Dominion Hills. In addition, ARMN member and Park Steward, Marion Jordan, reports that she and her team of volunteers have been fighting an infestation at Barcroft Park. Another stand of it was noticed by ARMN member Colt Gregory at Potomac Overlook Regional Park near the Visitor’s Center last summer. He and fellow ARMN members Linda Willen and Marion Jordan got permission from the park manager to deadhead it. Since then, volunteers have been digging the plants up, and plans are being made to replace them with native plants.

While you as a concerned citizen might want to grab the nearest pruners or shovels and attack this grass when you see it on public property, such as parks and stream sides, please resist the urge to do so on your own. The sites I discussed above are being worked by trained volunteers who have permission from local park authorities to do so. It isn’t that your enthusiasm wouldn’t be appreciated, but invasives-removal must be done by people who have had approved training on how to distinguish a true invasive from a native look-alike and on avoiding collateral damage to nearby vegetation or soils. If you see something you suspect is Cenchrus purpurascens growing in a park or other natural area, you should contact the park authority for the county or city where you found it to report the location so they’re aware of it in planning future invasives treatments. Most local jurisdictions prohibit the removal of any plant or animal material from parks or other natural areas without specific authorization.

Photo of two volunteers crouching to cut a big patch of ornamental grass. The grass is bright green with seed heads sticking out of the top.
ARMN members Linda Willen and Colt Gregory cut Cenchrus purpurascens at Potomac Overlook Regional Park. Photo by Marion Jordan.

More specifics about Cenchrus purpurascens 

I thought all I had to do was take some photographs and the iNaturalist identification app. would label it for me. It was more complicated than I expected because the plant is known by different names, including even more than one Latin binomial name!  It comes from tropical Asia and Australia and appears in the records both as “Cenchrus purpurascens (Thunb.)” and “Pennisetum alopecuroides (Spreng.).”  My first reaction was, “Wait, what the heck are Thunb. and Spreng?” I learned that they were botanists who separately named the plant: Carl Peter Thunberg, a Swede who studied under Carl Linnaeus in late 1700s, and Kurt Polycarp Joachim Sprengel, a German botanist working around the same time. 

I then decided to search the  Digital Atlas of the Virginia Flora, which identifies it under Cenchrus purpurascens and notes that “Molecular studies indicate that Cenchrus and Pennisetum form a monophyletic clade [meaning they had a common ancestor] and should be merged. Nomenclaturally, Cenchrus has priority over Pennisetum.” In addition, as noted above, the Plant Invaders field guide refers to it as Cenchrus purpurascens. It felt like a major victory to finally know the name of what to write about! (However, as explained above, be aware that you will also encounter it as a pennisetum.) 

Cenchrus purpurascens is also called various common names in the trade, including Chinese fountain grass, Chinese pennisetum, and swamp foxtail fountain grass. In addition, there are several cultivars of this plant sold in the landscape trade. (There is also a related grass called African fountain grass or Crimson fountain grass (Cenchrus setaceus). This fountain grass is more of a problem in Western states, however.)  By any name or any origin, avoid purchasing and planting any of these Cenchrus grasses. If you already own one, consider digging it up and replacing with a native alternative (discussed below), or cut off the seed stalks and put them in the trash at the end of the season before they spread. Please do not compost them or place them your organic yard waste bin. The seeds will germinate and keep spreading in the yards of people who use municipal compost in their own gardens. 

What Should You Plant Instead of a Non-Native Ornamental Grass?

If you want attractive ornamental grasses in your garden, there are locally native alternatives to Cenchrus purpurascens, such as river oats (Chasmanthium latifolium), purple love grass (Eragrostis spectabilis), pink muhly (Muhlenbergia capillaris), switchgrass (Panicum virgatum), and Indian grass (Sorghastrum nutans). These are all generally native to Northern Virginia, but it’s always best, check the Digital Atlas of Virginia Flora to be sure a plant is locally native to your particular location. 

While I will not go into it here, there are other introduced ornamental grasses such as Chinese silver grass (Miscanthus sinensis), which also seed themselves into natural areas and are becoming invasive. There are native alternatives to these as well. Take a look around your garden and see if you find some introduced grasses that you can replace with locally native alternatives. If that involves more work than you are up for, at least cut the seed heads off before they ripen and escape. You would be surprised how far away they can spread to our meadows, woods, and streams.

English Ivy, a Deadly Invasive, is a Winter Target for Removal from Local Parks

Text and photos by Nancy Cleeland

Like rust, English ivy never sleeps. It escapes yards and creeps down embankments and over rocks and up trees all year long. Planted by colonists in the 1700s and still sold in garden centers as a carefree ground cover, this ivy smothers the ground with dense mats and drapes the canopy with heavy, sun-blocking, deadly vegetation.

English ivy (Hedera helix L.) is one of the most destructive invasive plants in our local natural areas, according to the field guide Plant Invaders of Mid-Atlantic Natural Areas, which describes it as “an aggressive invader that threatens all vegetation levels of forested and open areas, growing along the ground as well as into the forest canopy.” Ivy outcompetes vegetation on the ground and trees for water and nutrients, and when it encircles trees, it holds moisture near the bark, encouraging rot. 

Close up photo of an ivy vine on a tree
Ivy close-up on trees at Spout Run.

According to the guide, “An infested tree will exhibit decline for several to many years before it dies. The added weight of vines also makes trees susceptible to blowing over during storms.” Also of note, English ivy only matures when it climbs, and then it produces berries that birds can carry long distances to infest new areas.

But there is some good news: With steady, determined effort over many years, English ivy can be cleared from invaded areas to the point that occasional sweeps are enough to keep it in check.

English ivy’s year-round growth habit makes it easy to spot in winter, when its waxy green leaves stand out from the brown landscape. Ease of spotting is one reason it is often targeted for removal at this time.

On a brisk morning in mid-February, about 30 volunteers gathered at a parking lot near Spout Run for a foray into National Park Service land along the George Washington Parkway, where the ivy was thick. Amy White, an ARMN member and Weed Warrior volunteer with the National Park Service who organized the event, described our priorities—freeing the ivy-choked trees that were still alive. Loppers and saws were the tools of the day; mere garden clippers were no match for vines at least several inches in diameter. 

Photo showing ivy covering the tops of three trees.
Ivy climbing and choking trees at Spout Run.

In clearing ivy, one must be careful not to pull the entire length of the vine, which can tear off attached bark and harm the tree even more. The recommended technique is to cut roots around the base or cut an ivy-free band around the trunk, as described on this ARMN web page. Unrooted, the vines will eventually die, turn brown, and disintegrate, allowing the tree to breathe again. The cut ivy can be left behind on branches and logs to dry out, as long as it doesn’t touch the ground to resprout.

It’s important to distinguish between destructive English ivy and beneficial native vines such as native wild grapes (Vitis spp.) and poison ivy (Toxicodendron radicans), which should remain untouched in parks and natural areas. 

We spread out, climbed the steep embankments and chose targets from among the many ivy-choked trees. In some cases, the ivy was so thick it resembled a second skin of bark. It can take 15 minutes or more to free a single tree in this state—prying a bit of ivy loose and sawing out a chunk, one at a time. What a great feeling it was to liberate a tree, which seemed to sigh its gratitude. 

We worked silently, focused on the task at hand. After a fast two hours, our scheduled time was up. Reluctantly, we packed up our tools and filed back to the parking lot. So many trees were left behind, but we had certainly made a dent in the problem. According to Amy, by morning’s end our group had “saved” about 300 trees. More events will be scheduled this spring.

In contrast, a few days earlier at Gulf Branch Park in north Arlington, a crew of volunteers fanned out and canvassed the ground for any ivy plant that dared poke above the leaf litter. The trees were gloriously free of choking vines.  Jen Soles, Arlington County’s Natural Resources Specialist, directed our group along both sides of the stream, where we also spotted and removed a few other early blooming invasive ground plants. 

Photo of the forest in Gulf Branch park.
Trees at Gulf Branch free of ivy vines.

Jen had been Park Naturalist at Gulf Branch for 10 years before her promotion, so she knew the terrain well. She recalled arriving at a park draped with choking ivy and chipping away at the problem over a decade. Volunteers from ARMN and other groups helped battle the vine, cutting it off trees and pulling roots out of the ground. It kept coming back. The game changer came when Arlington began using trained contractors to apply selective herbicides to the roots to prevent regrowth, she said. That combination of boots on the ground and expert application of herbicides eventually created the more natural landscape we see today. 

ARMN, National Park Service Weed Warriors, Tree Stewards of Arlington and Alexandria and more local groups clear invasive vines and other destructive non-native plants every weekend. If you’re interested in joining us to liberate a few trees from the deadly choke of ivy, check out ARMN’s Volunteer Opportunities page with a calendar of events.