Training Deer to Eat MORE Japanese Knotweed

This post represents a first for PrincetonNatureNotes.org, in that it is written by someone other than me. Mark Nowotarski lives in Stamford, CT, and contacted me more than a year ago after discovering a 2014 post I had written entitled Training Deer to Eat Invasives. Independently, he had begun foraging the Japanese knotweed growing in his backyard (young shoots are edible) and noticed that deer began browsing it as well. Released from any co-evolved limits on its growth, Japanese knotweed has spread across the US and globally, displacing native species and overwhelming any human efforts to counter it. Unlike people, deer are 24/7 land managers. Their appetites decide what can and cannot grow in our yards and woodlands. Training deer to eat a relatively edible species like Japanese knotweed could conceivably, in some situations, relieve browsing pressure on the native plant species deer tend to prefer. As the deer in Mark's backyard continued to consume young sprouts of Japanese knotweed, he sent me photos and text that I incorporated into a post a year ago.

This past growing season, Mark expanded his experiments and observations, exploring how a willingness to browse Japanese knotweed could pass from one generation of deer to another. It's still unclear how much of an impact deer browsing could have on the spread of Japanese knotweed, but it's an interesting inquiry. Along the way, we learn about deer family dynamics, the potential grazability of another uber-invasive, porcelainberry, and even the possibility that deer saliva affects the chemistry of plants. Thanks to Mark for sharing his work with us.

Training Deer to Eat MORE Japanese Knotweed

By Mark Nowotarski

In our post last year, “Training Deer to Eat Invasive Plants – Japanese Knotweed”, I shared observations of white tailed deer (Odocoileus virginianus) browsing a patch of Japanese knotweed (Reynoutria japonica) in my backyard in Stamford CT. The local deer had learned to browse the knotweed continuously from spring to fall resulting in drastically stunted canes. This had allowed numerous native plants to recolonize what had previously been an invasive monoculture. Steve and I speculated that perhaps if we cut the fully mature canes in other nearby patches of knotweed (i.e., coppicing), new shoots would grow and the deer local to those patches might browse the new shoots as well. I’m happy to report that that strategy at least partially worked.

Deer Raising Fawns on Knotweed

Before we talk about manual coppicing, let’s talk about how it’s occurring naturally. This first video, shot in May in my backyard, shows you what deer browsing spring knotweed shoots looks like.

A buck with new antlers approaches several knotweed shoots (Fig. 1). He gives a quick sniff, bites the top portions off, and eats them. The cut stems that are left behind are about 2 feet tall.

This particular buck may well be one of the fawns raised on knotweed in my backyard in the prior summer of 2024. Does and fawns form a family group when the fawns are born in late spring. They normally stay together and browse in the doe’s home range for a full year before dispersing shortly before the doe, if she’s pregnant, gives birth to the next year’s fawns. This is how last year’s fawns learn to eat the new shoots of knotweed that sprout in the early spring. The early spring browsing by last year’s fawns coppices the knotweed so that when it sends out new shoots at a convenient two foot height, the new shoots will be available for the new fawns born in late spring.

This year, our doe was, in fact, pregnant and sometime in June, she gave birth to triplets. Triplets are relatively rare (1 in 10 pregnancies) and indicate that the doe is well fed. By July, the doe and the new set of fawns were out browsing the knotweed previously coppiced by last year’s fawns before they dispersed.

In the foreground of Fig. 2 you can also see several native plants growing up through the coppiced knotweed. On the left is Canadian goldenrod (Solidago canadensis). On the right is Northern lady fern (Athyrium angustum) and sensitive fern (Onoclea sensibilis). The deer would occasionally take a nibble of the natives, but they concentrated primarily on the knotweed. 

This suggests that some of the native species less appealing to deer could begin to coexist with browsed stands of knotweed. I plan on trying this strategy next summer and will keep you posted.

I had set up a motion activated trail-cam to monitor how often, and for how long, the doe and fawns browsed the knotweed over the summer. They returned 4-5 times a week and browsed 5-15 minutes for each visit. This lasted from when I set the camera up in July all the way through late October when the knotweed senesced (i.e., dropped leaves and turned brown). So far this winter, the doe and fawns are still stopping by several times a week. In late October an 8-point buck also stopped by in the middle of the night. After a bit of hide-and-seek with the doe in the knotweed, they mated. We can now hopefully look forward to new fawns this spring.

The cycle of fawns being raised on knotweed and then dispersing in the late spring to new territories may be an important mechanism for the spread of knotweed browsing by deer. The question then becomes, can we spread it even further by coppicing canes ourselves.

Expanding Knotweed Browse with Manual Coppicing

At the same time I was monitoring the deer in my backyard I also set out this past year to explore the knotweed stands in our local parks and land trust sites to see if I could find additional evidence of deer browse. About half of the stands I inspected showed signs of early spring browsing. About half of the spring-browsed sites also showed continued summer browsing. Several of the summer-browsed sites showed a significant expansion of the browsed area versus last year. This was evidenced by areas with tall old canes from last year but only shortened canes this year. The deer hadn’t eaten the knotweed last year and it grew to full height. This year, however, they started in the spring and continued through the summer and fall keeping it short.

To try out the manual coppicing experiment, I selected four sites where there was either no early spring browsing or where there was some spring browsing but no rebrowsing of the new shoots emerging from the coppiced canes. Two of the sites did not show any rebrowsing of the coppiced canes. These sites either had no spring browsing or very scattered spring browsing. The knotweed threw out new shoots which grew to full height despite clear evidence (e.g. footprints) of deer wandering by. Apparently, the deer near those stands had not been sufficiently acclimated to knotweed as a source of food.

In the other two sites, however, the deer did resume browsing the new shoots thrown out by the coppiced canes. These sites had heavy spring browsing and well-worn deer trails right next to the knotweed stands.

The next set of figures shows the history of my coppicing experiment at one of the sites where the deer resumed browsing. 

Fig. 3 is a photo taken in April. It shows what an early spring browsed knotweed shoot looks like. It also shows a new shoot emerging from the cane a few weeks after the initial browse.

Unlike my backyard, however, these new shoots were not rebrowsed. By July they had grown to full height. This, along with the well worn deer trail right next to the knotweed stand, made it an ideal location for the coppicing experiment.

The next photo (Fig. 4) shows a section of the knotweed stand where I cut a 6 foot wide by 12 foot long section of the full grown knotweed canes to about 2 feet off of the ground. 

I cut the canes at a bias so that when I inspected them later on, I could tell whether a cut cane was my doing (angle cut) or a deer browse (horizontal cut). Cuttings were placed where they could not resprout or be washed downstream.

A few weeks later I went back to inspect and, much to my delight, the deer were browsing the new shoots emerging from the manually coppiced canes (Fig. 5). 

Where I had cut the canes, the ends were frayed and the canes turned black down to the next joint. Where the deer browsed the canes, however, the ends appeared to be sealed off and even flared out as if from accumulated water pressure coming up through the knotweed. The canes below the deer browse remained green. It makes me wonder if there is something in the deer saliva that causes a deer browse wound to heal quickly. Perhaps knotweed has evolved this way from browsing by sika deer (Cervus nippon) in their home range in Japan.

Once I confirmed rebrowsing of the new knotweed shoots at this particular site, I set up another trail cam to see what sort of deer were coming by. I half expected another family of a doe teaching fawns to eat knotweed.

 

Imagine my surprise when this magnificent 14-point buck showed up (Fig. 6). It wasn’t a family group. It was a bachelor group with up to four bucks coming through at various times.

This buck and several others came by 4-5 times a week to browse not only the knotweed, but the invasive porcelain berry (Ampelopsis glandulosa) growing over the area in the foreground and hanging off of the uncoppiced knotweed canes in the background. In fact, I suspect that the porcelain berry is the primary reason the deer were there. The knotweed was just an additional food source.

The bucks suddenly disappeared in mid-September after they shed their velvet, no doubt to pursue does during the rutting season. I have not seen them since except for one poor fellow with a missing antler. Given how well-worn the deer trail is, however, I expect to see at least some of them again in the early spring.

Deer in a given area learning to eat Japanese knotweed appears to be a multi-year process. It starts with initial occasional browsing of early spring shoots. The spring shoots are then browsed more intensely in the ensuing years. Eventually the deer start browsing the new shoots growing from the spring browsed canes. If the knotweed is in a doe’s home range, then she starts to raise her young on knotweed and then the process spreads as the fawns raised on knotweed go on to establish their own home ranges.

If you try your own coppicing experiments, please let us know how they work out. I’ve joined a project on iNaturalist called “North American Knotweed Ecology Project” where we can share our observations. iNaturalist is a great tool for finding knotweed stands in your area. If you look carefully in the knotweed photos, particularly those taken in April and May, you can often see a deer-browsed shoot here and there. Sites with browsed shoots would be a likely candidates for coppicing experiments.

In the future I hope to learn more about the general phenomenon of deer adjusting their diets to consume invasive plants; how this affects browsing pressure on native plants; and what impact it might have on the deer themselves. The deer won’t solve all of the problems with invasives, but they may very well be an important part of the solutions.

- Mark Nowotarski

Editor's note: A related initiative is the effort to train cattle to eat invasive species. A woman named Kathy Voth appears to be a leader of this approach. 

Year-End Update on Herrontown Woods - 2025

If you appreciate this blog, one way to give back is to support the work of the Friends of Herrontown Woods (FOHW), the nonprofit that we founded in 2013 to make the preserve usable again after long neglect. Our group now manages trails and habitat on 230 acres of municipally owned land in Princeton, and rely on donor support to pay our expenses. It's been a great year, and I'd like to share some of our accomplishments. Each donation provides support and inspiration for our work to restore habitat and history at Princeton's first nature preserve.

GOOD NEWS FOR PRINCETON'S SALAMANDERS

Herrontown Woods' large size, clean water, and wet terrain make it a haven for amphibians. The Princeton Salamander Crossing Brigade, founded by FOHW board member Inge Regan, is in its third year of helping hundreds of salamanders and frogs safely cross the road during their spring migration. 30 participants include experts and beginners, Princeton High School students and faculty, professors and community volunteers. A lively dialogue via whatsapp continues yearround. 2026 will mark a breakthrough, as Princeton municipality has agreed to close the road during the rainy nights in early spring when the amphibians are on the move. The initiative was written up in the Town Topics, TapIntoPrinceton, and the Daily Princetonian.

THE BOTANICAL ART GARDEN ("BARDEN")

Visitors to Herrontown Woods often describe it as "magical" and "unique." The award-winning Barden contributes a lot to that impression, having evolved since 2017 through a merging of many talents and visions. We keep adding native plants--some 160 species thus far--and have done surprisingly well at catching the weeds before they can spread. Kids love the charismatic wood frogs in the spring and the green frogs that take up residence in the summer. On the first Sunday morning of each month, we host a May's Cafe next to the gazebo, with coffee, tea, and baked treats. 

SURPRISING SUCCESS WITH INVASIVE SPECIES

People are used to bad news about invasive species, but by being proactive we have largely vanquished many kinds of invasive plants that plague other preserves. In particular, through early detection and rapid response, we continue to protect Herrontown Woods and Autumn Hill Reservation from the uber-invasive lesser celandine. We also saved many trees by slaying a giant "wisteria monster" around Veblen House, and more recently have subdued another, nearly 3 acres in size, over near the main parking lot. Timely intervention is also protecting the preserves from Japanese angelica tree, bush honeysuckle, jetbead, porcelainberry, garlic mustard, mugwort, Chinese bushclover, and a new invasive shrub/tree so little known that it lacks a clear name. Late summer intervention is helping limit the spread of stiltgrass. All of this has been achieved through steady, incremental effort year after year by our volunteers and paid interns.

A COMBACK STORY FOR NATIVE SHRUBS

Native shrubs have a hard time of it in Princeton preserves. The combination of deep shade, deer browsing, and competition from invasive species has caused many types of native shrubs to literally lay low. The town's deer management program has helped, but pinxter azaleas, Hearts a' Bustin', and shadbush in Herrontown Woods still persist only in miniature, unable to flower. By transplanting some of these to sunnier spots in the Botanical Art Garden and caging them to protect them from deer, we are showing the public a beauty and vitality that had previously been suppressed. We're giving other native shrubs the sunlight and protection they need as well: alternate-leaved dogwood, silky dogwood, elderberry, buttonbush, and swamp rose.

A FLOURISHING WET MEADOW

Another successful FOHW project is managing the wet meadow at nearby Smoyer Park. Fed by runoff from the parking lot, it's actually a lowly detention basin converted by Partners for Fish and Wildlife long ago to native meadow through our initiative. Girl scouts had fun adding wildflower seed collected locally. A meadow is vulnerable to takeover by invasive plants like mugwort, Chinese bushclover, Canada thistle, and crown vetch, but strategically timed work each year to discourage those species has paid off. Each year the work has gotten easier as the weeds become fewer and fewer. Natives flourish if given a chance.

MAINTAINING AND IMPROVING TRAILS

FOHW was able to coordinate rapid response to clear trails and grounds after major storms this year. Winter is actually a great time to scope out routes for new trails. This year, we created a Black/White trail--to serve as an intro to Herrontown Woods for those entering the preserve from Princeton Community Village--and extended the Blue Trail down through the  "Valley of the Giants," where there are some particularly large tulip trees and oaks. Over the past three years, we've also been shifting some trails at Autumn Hill Reservation to drier, more open ground. Meanwhile, the long, locally sourced boardwalk extending from the main parking lot up to Veblen House has been getting rave reviews. We call it the Voulevarde, because it was crafted by chainsaw virtuoso Victorino, and leads to Veblen House.

NATURE WALKS

In addition to periodic nature walks by Steve Hiltner, Sarah Roberts, and others, FOHW offered forest bathing walks this year, led by Rich Collins of the Friendly Territory. Steve continued to lead walks through the Princeton Adult School on Herrontown history, ecology, and geology.

EVENTS

Along with our ongoing traditions of hosting the Lunar New Year, Earthday, the Veblen Birthday Bash, and other events, we had for the first time dancing, as part of a festive performance of Celtic and folk music by the Chivalrous Crickets.

COMMUNITY OUTREACH

FOHW is in its second year of collaboration with Princeton High School, providing expertise and mentoring as we work with Jim Smirk's environmental science students to manage two detention basins for native diversity. Students learn ecological analysis techniques while doing hands on work to weed out invasive plants. These wetlands conveniently provide complex native habitats on school grounds for study. Focus in 2026 will be restoring ecological health to one of the basins, the Ecolab Wetland, which was disrupted by necessary infrastructure repairs completed earlier this year.

GARDENING CLASSES AT MAY'S GARDEN

May's Garden--the restored and now expanded fenced-in garden site where Elizabeth Veblen once grew her vegetables and flowers--completed its third year under the inspiring leadership of master gardener Mathilde Burlion. Assisted by Andrew Thornton, Mathilde led many Grow Little Gardener workshops for young families. 

HERRONTOWN WOODS COMMUNITY COLLAGE

Conceived by artist and board member Hope Van Cleaf, the Herrontown Woods Community Collage is modeled after the mural in the Princeton Public Library. Hope has been conducting workshops in the Barden and elsewhere, with each participant contributing their artistry. The individually created tiles will be brought together on a wall in 2026 at Veblen House. 

SPRUCING UP VEBLEN HOUSE AND COTTAGE

New board members Ben Schaffer and Derek Reamy have been instrumental in organizing and sprucing up the buildings and grounds, and adding momentum to renovations. 

AN INSIDE-OUT MUSEUM

The windows and walls of the House and Cottage are being used to tell the many stories of the buildings and the fascinating people who called them home. The story of the Veblens' extraordinary lives and contributions were the first installation. To be added are the stories of the Whiton-Stuarts--the original owners who sold the house to the Veblens in 1941--and the small-holder farmers who built the 1875 farm cottage. Much research has been published at VeblenHouse.org.

COLLABORATIONS WITH PRINCETON UNIVERSITY 

Visits by Princeton University students noticeably increased in 2025. Ecology professor Andy Dobson again brought his popular undergraduate ecology class to Herrontown Woods for a tour.  Graduate students from the Princeton School of Public and International Affairs offered spirited help during workdays. Members of the university's Princeton Birding Society led our Backyard Birdcount. We also hosted visits and workdays through Outdoor Action for incoming freshmen.

STEWARDSHIP INTERNS

FOHW is grateful to Green Matters for having funded summer internships in 2024 and '25. Interns Ninfa and Moss worked through the summer, keeping trails clear, cutting invasive species, and helping with events. Moss headed back to college in the fall, while Ninfa will continue to work part-time at Herrontown Woods through the winter.

GRATITUDE YOGA

We are also very grateful to Gemma Ferrell for continuing to conduct her popular Saturday morning Gratitude Yoga classes during the summer and fall on the grounds next to Veblen House. The classes are donation-based, and all donations go to FOHW. 

VALUING, RESEARCHING, AND PRESERVING HERRONTOWN'S RICH CULTURAL HISTORY

Oswald Veblen's extraordinary career has been gaining increasing attention since FOHW president Steve Hiltner began researching and posting about the Veblens at VeblenHouse.org in 2010. On Sept. 4 this year, Steve teamed up with historian Cindy Srnka to present a talk at the Princeton Public Library entitled "How Oswald Veblen Quietly Created Einstein's Princeton." Drawing a standing room only crowd, the talk described how Veblen played an outsized role in creating the Princeton that Einstein ultimately chose to be his new home. 

Also in 2025, an online exhibit by the Institute for Advanced Study credited Oswald Veblen for his leading role in aiding displaced scholars in the 1930s and '40s. And Princeton University named the South Terrace at Prospect House in Veblen's honor.

THANK YOU TO THE FOHW BOARD, VOLUNTEERS, AND SUPPORTERS

So much goes into sustaining a nature preserve and the nonprofit that cares for it. As we bring our mix of tradition and innovation into 2026, I'm tremendously grateful to our board, volunteers, and supporters who contribute so much meaning, community, and all-round positive energy to this charmed place in Princeton. 

Playing the Healer of Nature

One of PrincetonNatureNotes' sister blogs is FOHWard.org, specific to our work and play at Herrontown Woods, the fabled preserve that our nonprofit Friends of Herrontown Woods takes care of. Posts range from the celebratory to the comic, as in when we intervened to scuttle an attempted "theft" of a portapotty. 

For those who imagine cutting invasive species to be dull work, a recent post on that blog, Stewardship and Discovery at Herrontown Woods, might be of particular interest. It captures how elements of beauty, effort, strategy,  serendipity, and discovery can come together to make a stewardship session a rich and satisfying experience. 

Cutting nonnative invasive shrubs, we are essentially deer with loppers. Deer move through the forest looking for something edible to browse. They generally leave the nonnative shrubs uneaten, and so to prevent those nonnative, inedible shrubs from taking over, we move through the forest with our loppers with an eye for "browsing" the nonnatives, to balance out the deer's persistently lopsided appetites. Unlike deer, we aren't in the woods 24/7, and so to have a lasting effect it's necessary to treat the cut stem so it won't grow back. By releasing native plants from competitive pressure, over time we make the forest more edible for deer and other wildlife, essentially expanding the acreage of functional habitat in Princeton. 

Some would say that humans are an invasive species, so who are we to presume we can make a positive difference. But if we can be considered invasive, we are also equipped to play the role of stewards, to see the consequences of our invasiveness and act to heal the altered earth. As we move deer-like through the forest, our appetite is not an extractive search for food but for restoring balance. To abdicate on that role would be to deny what it means to be human.

I don't know if deer can appreciate beauty or serendipity as they browse, but we can. In Herrontown Woods in autumn, each leaf reveals its inner color. Each boulder is a work of nature's art, mottled with varied shapes of lichen and moss, like the mottled skin of whales navigating the oceans. To steward a preserve is, of course, a considerable task and responsibility, but in another way, working with nature is a great privilege, allowing us to realize our highest role, as stewards, appreciators, and healers of nature's creations.

Encounters With Old-Growth Forest

Ever since attending the induction of Rutgers' Meckler Woods into the Old-Growth Forest Network, I've wondered whether any woodlands closer by could be rightfully considered old-growth. Rare is the woods that was never logged. The forests we typically encounter are of more recent vintage, having mostly grown up from abandoned farm fields. There's a valley at Herrontown Woods with giant tulip trees whose massive roots have lifted the ground around them, as if perched on a pedestal of their own making. Might these and the nearby big oaks and hickories meet the standard? And what exactly is the standard for deciding? Below is an account of encounters with old-growth, old stuff, and different forms of timelessness during recent travels.

When we headed north from Princeton to attend the wedding of a young couple in upstate NY, we had no idea that the theme of the trip would turn out to be old stuff and old growth. On the way up, we stayed overnight with friends whose house is filled with old furniture--a grandfather clock, of course, but also what may as well be called grandfather chairs that had been inherited or adopted from the curb, valued for their uniqueness and style regardless of how practical they might be. Each chair around the dining room table, each lamp, vase, and bureau, had a story behind it. A crank telephone perched on the wall in the kitchen, ready to call up the whisperings of distant ancestors. I found great comfort in this approach to stocking a house, even if a chair's quirky ergonomics didn't conform to modern expectations.

The next morning, we walked through Borden's Pond, a second growth woods whose scattered "wolf" trees and sedge meadows also have a story to tell. When the area was logged long ago to make pasture, farmers left a few scattered trees as shade for the livestock. Those trees, lacking any competition, with sun all around, grew thick lateral branches, so different in shape from the straight, younger trees--the "second growth"-- that grew up after the pasture was abandoned. This can't be called old-growth, I suppose, but it certainly has individual trees that go way way back.

Conveniently, the route to the wedding took us by Landis Arboretum, which too had some craggy old trees, standing next to the farmhouse. In the woods beyond, though, was an area declared to be old-growth, with a series of signs explaining how to distinguish old-growth from the second growth forest all around.

Don't expect big trees only, but a few big trees lingering in a mixed age stand. Around six old trees per acre is typical. In this photo, only one of the trees can be considered old growth, in this case a hemlock extending back 250 years. 

Really old trees lose their symmetry, with thick upper limbs and tops broken off by storms endured over the centuries, creating what's called a "stag-headed top." Look for mounds and pits on the forest floor--undulations caused by the lifting up of root balls as trees fall. And look for coarse woody debris on the forest floor in different stages of decay, where stable conditions and slow decay have allowed opulent growth of moss and fungi. One of the interpretive signs offered a clever way to judge a tree's age, not by its diameter or height--since some trees grow much faster than others--but by how far the moss has managed to grow up the trunk. 

One week later, I was in Durham, NC, where I started a watershed association 26 years ago, creating a string of preserves before moving to Princeton. I always get together with my botanizing buddies when I visit, and this time Perry Sugg, Cynthie Kulstad and I decided to stop by the 82 acre Glennstone preserve I had worked with a developer to create. We were walking down a sewerline right of way, with no particular destination in mind, when I thought of a special place to visit.

Just down the hill from the remains of a summer cottage, next to a rocky creek, are the remains of a spring where the owners of the cottage must have gotten their water. A small pipe sticks out of this half circle of stone, near the bottom. The ground there is consistently wet, but I've never seen water actually flowing out of the pipe. Last time I'd been there, I'd found a robust patch of JoePyeWeed, a tall wildflower found nowhere else in the preserve. This was also the only place I've seen smooth alders in the area. Apparently, the stable water source allowed the plants to survive droughts.

On this visit, armed with awareness gained at Landis Arboretum in upstate NY, I was able to focus in more on what sorts of trees were growing nearby. Past logging had left only narrow corridors of the original forest intact. Buffer regulations had forbidden harvest of trees within fifty feet of the stream. One tree in particular caught my eye, a towering shortleaf pine. 

The rough bark at its base brought to mind the Landis Arboretum signage:

"The bark changes on most species when the trees are over 150 years old, looking very different from the bark of younger trees.

Excellent signs include balding bark, shaggy bark (separating or curling strips), craggy bark (deeply grooved, fissured bark), and platy bark."

On this particular shortleaf pine, the bark changed dramatically about 20 feet up, from shaggy to smoother, platy bark extending to the top. That would suggest the tree is well over 150 years old.

The bark at the base was deeply grooved. 

Other large trees with distinctive, eccentric bark rose from the creekbanks. I doubt that this narrow band of mature trees along a stream would fit the definition of old-growth forest, even if the trees were old enough. The Network prefers stands of at least 20 acres. If there had been time, we could have followed this narrow band of old trees downstream, to better dream of what this woods had been before the logging. 

Late afternoon light caught the tops of these towering remnant trees rooted in a distant time yet still growing towards the sun. The experience of being there in that charmed hollow was not unlike the sense of timelessness felt while staying in our friends' house with furniture firmly rooted in the past. 

Keeping with the theme of old stuff, the young couple's wedding reception took place in the Hotel Utica, dating back to 1912, with massive, ornate chandeliers and tree-like columns. The groom's father was happy his son had chosen a place so steeped in history, but mourned that the glorious woodwork had been painted over during a recent renovation. 

It was the groom's father's idea to include an antique phone booth at the reception, where wedding guests could leave a message for the newlyweds, using an old dial phone. 

Click on "read more", below, for text from the Landis Arboretum's interpretive signage, describing in more detail the qualities to look for in old-growth forest.

 

The Mystery Tree Found in Autumn Hill Reservation

Not everyone gets to discover and report on a new invasive species in one's adopted home town. Though there were a couple kinds of invasive plants that I caught early enough to hopefully keep from spreading through town--thorny mile-a-minute and more recently the dreaded common buckthorn--this particular discovery is different, in that people have yet to agree on what it is. How strange it can feel, in a time when the internet can instantly tell you everything about everything, to find a plant to which no one can with certainty give a name.

I first encountered a single specimen of the mystery tree while conducting a plant inventory in Roger's Refuge in 2007. Only in the past few years have I found it proliferating in Herrontown Woods and Autumn Hill Reservation. 

Some call it a shrub, though when it grows to 30 feet, maybe it's time we start calling it a tree. There's agreement that it is in the genus Pourthiaea--a name that people will struggle to spell and pronounce (my attempt at a pronunciation is "pore-THEE-uh"). In a discussion on iNaturalist, the citizen science site for reporting and identifying species, some try to call it asian photinia (Pourthiaea villosa)--a nonnative shrub that likely escaped from Princeton-based nurseries long ago.

They are surely wrong, as the leaf shape and fall color of asian photinia are clearly distinct. This bright golden yellow is increasingly prettifying and clogging Princeton's greenspaces, from the Institute Woods in the west to Autumn Hill in the east, creating dense, exclusionary stands as it spreads beyond Princeton to proliferate across New Jersey. 

John L. Clark, a Princeton-based botanist frequently posting on instagram from the forests of Equador, has done a great deal of research into our mystery tree. Since the Pourthiaea genus originated in China, John tracked down a couple Chinese botanists to seek their insights. 

One, D.Y. Hong, responded that he was too old to take on the challenge of identifying the tree.

Another, Bin-Bin Liu, was also apparently unable to assist. John laments that botanists now trained in phylogenomics can identify gene sequences but not the actual physical plants themselves. 

There have been various species names thrown at the mystery tree--lurida, lucida, arguta--but none clearly stick thus far. Through Mike Van Clef, I learned of Jean Epiphan, a northern NJ plant expert at Rutgers, who had arrived at the species name "parvifolia", and even came up with a common name, "littleleaf photinia." Originally introduced in 1908 at the Arnold Arboretum," it's popping up in Morris County and, according to Jean, matches our mystery tree in Princeton. She has not seen it being sold in nurseries, and speculates that it is spreading from specimens in old estates. She sent a couple links (here and here) with descriptions, and a mention of it in Dirr's encyclopedic Manual of Landscape Plants.

Some sticking points, though, are that the link she sent to a photo has now gone dead, and the description is of a shrub less than ten feet high. A photo sent by Pat Coleman from Bowman's Hill Wildflower Preserve also matched our mystery tree in Princeton, but no word as yet whether they've come up with a name.

One thing to call the mystery tree is pretty, as are many invasive shrubs, both when they bloom and in the fall. This fall in particular, Autumn Hill Reservation was a jubilant jumble of colorful invasive shrubs, led by the bright red of winged euonymus, joined by the rich colorations of Linden viburnum and the golden yellows of the asian photinia Even the lowly privet got into the color game with an appealing dark bronze. 

When surrounded by such a dazzling visual display, it takes work to remind oneself that something important is being lost as these introduced species gain dominance in the understory. Their success and dominance is enabled in part through being rejected by deer, which prefer a diet of native plants. Thus, our eyes are well fed while the wildlife find themselves living in an increasingly inedible forest. 

As we lose many of the native trees dominating the canopy--chestnut, elm, ash, and now the beloved beech--the extra light reaching the understory drives the extravagant growth of nonnative shrubs. Surrounded by such a thorough invasion of nonnative growth, it is extraordinarily intimidating to contemplate the work involved to shift the balance back to the spicebush, blackhaw viburnums, blueberries, hollies, sumacs, and other natives currently getting smothered beneath the rising tide.

Native shrubs and trees don't exactly lack color. Here's a dogwood that was mixed in and easily confused with the mystery invasive. Note the way the leaves are paired rather than arising one at a time along the stem. 

All the invasive shrubs currently dominating were at one time, long ago, in a similar state, just starting to pop up here and there. Clearly there was no one back then able to see the future and take early action. In our era, the consequences of inaction are readily apparent. What is special about this moment in the history of Autumn Hill Reservation is that the mystery tree is still early enough in its invasion, and easy enough to spot in fall, that it can be stopped.  

Update:

Where found thus far:

• Rogers Refuge, Herrontown Woods, and Autumn Hill in Princeton
• Possible sighting in the Institute Woods in Princeton
• Bowman's Hill Wildflower Preserve
• Jockey Hollow and the NJ Brigade Area in Morris County
• Tourne Park, in Boonton

Update: A big thank you to "anonymous" in the comment section, who provided a species name and links to herbarium photos:

"Thanks for alerting us to this newly naturalized species. One of the best resources for documentation of plants on a global scale is GBIF. Reviewing the gallery of specimens online, the name leaves to appear to bear a resemblance to Photinia parviflora. https://www.gbif.org/occurrence/gallery?taxon_key=5363981"

Each photo at the link bears the name C.K. Schneid. Look at the wikipedia page for Camillo Karl Schneider and you'll find that he was a German botanist who traveled to China in 1913 to collect plants and seeds. His next stop was the Arnold Arboretum in Boston, where the species is said to have been introduced five years earlier by Wilson in 1908.

Each photo shows that the now accepted species name is not parvifolia but instead parviflora. 

Applied name Photinia parvifolia (Pritz.) C.K.Schneid.
Accepted name Pourthiaea parviflora (Cardot) Iketani & H.Ohashi

That puts into question the common name "little leaf photinia", since "parviflora" means little flower. 

So, we're not really there yet. 

Fall Colors Nature Walk, Sunday in Herrontown Woods

Early November, and it's time for a nature walk through the color-coded forest of Herrontown Woods. Color-coded because each tree and shrub is showing distinctive coloration that can make it a snap to identify, even from great distance. 

The walk will head out at 11am this Sunday, Nov. 2, from the gazebo at the Botanical Art Garden (Barden), next to the main parking lot, 600 Snowden Lane. The walk is free, but donations to the Friends of Herrontown Woods are welcomed.

Come early and enjoy coffee and baked treats at May's Pop-up Cafe in the Barden from 9-11, and with all the fall colors, take part in an art project called the Community Collage. 

Along with colorful leaves--still on branches or lying in a colorful collective on the ground--we'll see the bright berries of Hearts 'a Bustin'. If you look closely, you'll even see witch hazel in full bloom. 

Here are four native shrubs that have shown particularly bright fall color: blackhaw Viburnum ("blackhaw" means black berry),

a highbush blueberry along the Veblen House driveway,

winged sumac (a "volunteer" that popped up at the Barden),

and a particularly showy Hearts 'a Bustin' in my backyard.