A Spring Walk Through Herrontown Woods

(This post from 2017)

Update: We had a wonderful spring nature walk at Herrontown Woods on Sunday, April 23. It was Earthday weekend, which is part of Earth Month, Year, Century, and miscellaneous millennia extending out beyond, towards infinite. Earth takes care of people day in and day out, so it's only fair that we return the favor.

Below is a virtual version of the walk along the red and yellow trails past vernal pools and boulder fields, all graced with wildflowers and the babble of brooks this time of year, then past the daffodil-strewn Veblen farmstead and over to the Veblen House grounds for refreshments.

Head down the parking lot to the Red Trail, and the first thing you encounter in spring is the vernal pools that form in the holes left by trees uprooted by storms. It's fun to search the banks of these pools for the well-disguised wood frogs.

It was a weird early spring, with summer-like heat followed by snow-come-lately, but some frogs managed to leave globs of eggs behind. Mosquito wigglers promise a good food source whenever the eggs get around to hatching.

It's proving to be an unusually good year for trout lilies--the yellow flowers with trout-like mottling on their leaves. Most years, one sees abundant leaves on the forest floor, but few actual flowers.

Spring beauty is a more dependable bloomer.

The Yellow Trail branches off from the Red Trail just past the stream crossing, then follows the stream up to a convergence. The opulent leaves of skunk cabbage make these streams a ribbon of green in spring. Take the stone stream crossing to stay on the Yellow Trail.

Here's an impressive lean-to someone built, using the crook of a tree to support the central beam.

Along the stream is some scouring rush (Equisetum), which we discovered on a walk with kids from the nearby Princeton Learning Cooperative. You can pull apart its segments, and use their abrasive silicon texture to sand a clarinet reed, or scour whatever needs scouring. It's a very primitive plant, and small compared to its tree-sized ancestors from the Carboniferous era.

Jack in the Pulpits are getting ready to preach.

Rue anemone lines some sections of trail, giving the impression that the edges of trails offer a particularly conducive habitat, where wildflowers are less impeded by the forest leaf cover.

We may also see wood anemones and Virginia pennyworts. I'm told that the pennyworts have an S2 designation in NJ, meaning S2, which means "imperiled because of rarity (6 to 20 occurrences)". This speaks to how important it is for us to carefully manage Herrontown Woods to protect its diversity.

As the Yellow Trail climbs the slope of the Princeton Ridge, you can see the surrounding understory turning green with, alas, winged Euonymus. That early green flush of species that evolved on other continents can shade out the native spring wildflowers, which depend on that sunlight streaming down unimpeded, to recharge their roots with enough energy to bloom the next year. Native trees and shrubs are slower to leaf out, and so give the native wildflowers the "window of opportunity" they need.

Along the trail, you'll see many of the winged Euonymus were cut. We're experimenting to see if the deer will follow up and eat the resprouts. 

It takes awhile to notice the subtle beauty of flowering sedges.

Mayapples are numerous, though relatively few can be found with flower buds.

Near the top of the yellow trail, before it swings over towards the quarry area and farmstead, is a favorite spot: the boulder field.

A stream flows through the boulders, with enough current this time of year to create a wonderful stereo effect with gurglings of various pitches. These sounds mix with birdsongs, the occasional small plane coming or going from Princeton Airport, and various rustlings of wind and wildlife to create that special seductive serenity of Herrontown Woods. I'd suggest that it was that serenity that drew Oswald and Elizabeth Veblen out to this part of town, and led ultimately to the land being preserved when the Veblens donated it all for public enjoyment.

Here's one of the native shrubs--spicebush--which make subtle, fleeting clouds of yellow in the understory. If the shrubs benefit from an opening in the tree canopy, they get enough energy to make bright red, lipid-right berries for the birds.

Here's the mystery Viburnum. Only a few specimens at Herrontown Woods. There are various natives--V. prunifolium, V. dentatum, and V. acerifolium--and the nonnative Linden Viburnum. But this is not any of those.

Update: Thanks to Henry Horn for putting me in touch with Michael Donoghue of Yale for an ID of this shrub: Tea Viburnum (V. setigerum), a Chinese species "that is escaping and becoming established in several areas in North America."

Part of the charm of Herrontown Woods is its farmstead (photo below), which includes a small red barn and corncrib, and the shingled 1875 farmhouse known as Veblen Cottage. Many people confuse the cottage with the Veblen House, which is a couple hundred feet away, through the high fence. These daffodils were either planted by Elizabeth Veblen or by one of the local garden clubs that showed their love for the Veblens and Herrontown Woods by caring for the gardens well after Elizabeth passed away in 1974. The daffodils went unnoticed until Friends of Herrontown Woods board member Sally Tazelaar removed all the multiflora rose that had grown over them.

The current owner of these buildings, Mercer County, has taken initial steps that, if not countered, would lead to their demolition. They are in fine shape and remind park visitors of Princeton's farming heritage. Our nonprofit, the Friends of Herrontown Woods, has submitted a proposal to acquire and maintain these buildings with the same love and commitment we have shown by taking care of Herrontown Woods for four years.

Update, April, 2021: The Friends of Herrontown Woods and its supporters convinced the town to take ownership of Herrontown Woods from the county, and lease the buildings to our nonprofit to begin repairs.

Learn more during the walk, and consider getting involved via our FOHW.org website.

Kayaking Up the Mighty Millstone Marsh

If you ever tire of land, Princeton offers a complex of waterways that can be easily navigated by kayak or canoe. There's Carnegie Lake, of course, but also the canal, Stony Brook, and the Millstone River, which flows through a beautiful marsh just a few paddle strokes upstream of Carnegie Lake. A friend, who in the acting world goes by the name of Basha, had been singing the praises of the marsh this year, and we finally headed over there this past Saturday in late afternoon. The put-in is over towards Plainsboro, off Mapleton Road, next to the aquaduct parking lot.

If you've lived in Princeton for ten years without knowing where the aquaduct is, it's where the Millstone River ducks under the DR Canal, downstream of the Harrison Street crossing. Near this "aquaduck" is a pair of mute swans (a species of Eurasian origin, easily distinguised from indigenous trumpeter and tundra swans by its orange bill) that have become the DR Canal's version of rock stars since they had three babies, properly called cygnets. They quickly realized we had no food to offer. Body language here is suggesting which adult is the mother.

The wilder world of native plants and wildlife is accessed by paddling to the left, through a channel bordered by masses of spadderdock,

then under the newish Route 1 bridge.

The channel begins to narrow. The slim profiles of egrets, standing still in the water, become masses of pure white as they spread their wings to fly off. The native rose mallow hibiscus lines the banks in full bloom.

Along the banks and extending deep into the shadows are cardinal flowers, thriving in this year's rains.

Always on the lookout for something new, I found a marsh St. Johnswort (Triadenum virginicum), blooming on the bank.

This, too, was a welcome sight: partridge pea, apparently planted in a restoration site on the east bank. It used to have an easier latin name until someone changed it to Chamaecrista fasciculata. It's closely related to the sensitive pea (smaller) and wild senna (larger), both of which can also be found growing wild in Princeton, particularly along the canal.

One battle I fought for awhile was to get departments of transportation and other governmental entities to stop using the highly invasive Sericea lespedeza for erosion control and start using less obnoxious plants like partridge pea. Sericea lespedeza, also called Chinese bushclover or Lespedeza cuneata, is now taking over the gas pipeline right of way in Princeton, and is a big problem in tallgrass prairies in Kansas and elsewhere.

More successful was the battle fought by Basha and others against the Millstone Bypass, a road that would have been routed close to the Millstone marsh. She's keeping her files, knowing that bad ideas never die.

Another wildflower common in the marsh and along the canal is climbing hempvine. No relation to hemp.

One remarkable sight was wild string beans, produced by the native groundnut. In my garden, it has begun to take over since a tree was taken down and the extra sun fueled this vine's ambitions. Groundnut tends to produce lots of flowers but no beans, as if the flowers were a front organization distracting attention from the underground spread of its tubers. In the wild, it needs that aggressiveness to compete with the other aggressive species along the shores. The tubers, by the way, are said to be edible, and some efforts have been made to breed this plant for commercial food production.

It's a good year for arrowwood Viburnum berries. Note the toothed leaves, thus Viburnum dentatum.

Nearly all the buttonbushes had finished with their golfball sized blooms. Some had improbably oversized leaves. Buttonbush grows well in standing water along the shore, but can also prosper in wet ground in the backyard. In fact, many of the native plants flourishing in the marsh also do well in constructed raingardens in town.

Once you're up in the narrower portion of the marsh, it's best to keep right. Basha showed where heading to the left leads to a deadend. There's a low fallen tree you'll need to duck under at one point.

Mysterious but cleanish looking fluids spill from a pipe with Sarnoff's name and phone number printed above. Just out from this outfall, the surface of the stream is broken by periodic upwellings of water from down below. A faint smell of treated sewage can be detected.

Paddling further up would lead eventually to the overpass for the NJ Transit train, but even a brief visit to the lower end of the marsh has a wild feel to it. Among other sightings were great blue herons, a weasel, turtles, ironweed, and some less charismatic native plants like tearthumb. Beavers like the area, and have been known to slap their tails on the water to warn anyone getting too close.

Even a pile of branches rewards, or warrants, closer inspection.

On the way out, we again passed the resident egrets. A bald eagle flew overhead on its way down Carnegie Lake. Though we could have lingered longer and continued upstream, the whole trip took less than two hours. What a treat to have such habitat so easily accessed just outside of town, and thanks to Basha for the tour.

Princeton Bible Church Brings Their Green Project To Mountain Lakes

Many thanks to all the members of the Princeton Bible Church Green Project who came to Mountain Lakes yesterday to help with removal of invasive shrubs.

Andrew Thornton (right) helped show everyone which shrubs were exotic and needed to be cut.

Four hours of steady effort with loppers and pruning saws cleared a large swath of exotic understory beginning at the Mountain Lakes House parking lot

and continuing down the slope to the lakes.

 Our youngest helper, after carrying some sticks to the brushpiles volunteers made for habitat, took a great interest in all the clipping going on.

This spring, inspired by the ongoing restoration of the dams and lakes by Princeton Township, and all the updating inside and outside of Mountain Lakes House, we're focusing on restoring habitat on the slopes surrounding the lakes.


Exotic shrubs cut: honeysuckle shrub and vine, privet, Asian photinia, and the occasional Linden viburnum and barberry.


Native shrubs and small trees left to grow: Blackhaw viburnum, sassafras, flowering dogwood, silky dogwood, false indigo.

The Second Forest of Institute Woods

In the Institute Woods, towards the end of the day, towards the end of autumn, it's not just the trees that cast long shadows. In the understory, a shadow forest grows, composed mostly of nonnative shrubs--winged euonymus, linden viburnum, asian photinia, shrub honeysuckle, multiflora rose and privet. Having evolved on a different continent in a different climate, they hold their leaves long after most of the native woodies have dropped theirs. Dominating the understory, these shrubs and vines constitute a second forest that serves up a second autumn, shedding their conformist green to show late-season reds and golds. 

There are second forests all around Princeton and beyond. The light green close to the ground in this photo is honeysuckle shrubs along Terhune Rd.

Here, viewed from the Streicker Bridge over Washington Road a week or two ago, are Norway Maples pushing up into the canopy of mature native oaks, beech, and blackgum, some of which are two centuries old. 

Bamboo at the Princeton Battlefield, bordering the Institute lands, offers another variation on the theme.

The different colors of the second forest provide a convenient code for easy long-distance identification. The pink here, down near the Friends Meeting House entrance to Institute Woods, means you're looking at winged euonymus. If it were growing in full sun, the color would be a vivid red, from which comes its other common name, burning bush. 

Here the pink of the winged euonymus mingles with the still green multiflora rose. 

Linden viburnum has its own distinctive fall color, 

as does Asian photinia, whose leaves tend to be broader towards the tips. It's usually more golden than this photo shows, and in Mountain Lakes and along Princeton Pike has turned whole woodlands golden this time of year. 

Mingling with the photinia here is the viny ever-green Japanese honeysuckle. 

Wineberry, with its fuzzy purple stem, is another Asian species with lingering green in late fall. 

Privet holds onto its green as well, here growing up around the tan stem of a shrub honeysuckle. 

Add global warming, which is bringing unusually warm and comfortable autumn days, and the feeling of gratitude for unseasonal warmth and color begins to  mix with a foreboding about the ecological consequences. Awareness creates an emotional undertow pulling against the uplifting effect of weather and color. The second forest flourishes in part because it is inedible to wildlife, which prefer and depend upon native species for food. The colors that greet our eyes this time of year signal a diminishing edibility for the forest's inhabitants. 

Four plaques tell the story of how the Institute Lands were saved from development in 1997, a half century after they were acquired. Though a couple key elements are left out--the Lenape Indians and Oswald Veblen--it is an extraordinary story, listing the major donors, 

the Taplins who led the way,

the coordination of governmental, institutional, and nonprofit entities that in NJ has been so effective in saving land. 

You can click on each photo to hopefully make it large enough to read.

Here, on this plaque, would have been a good place to mention the Lenape Indians as early occupants and stewards. A whole additional plaque could be dedicated to telling of Oswald Veblen's role as primary instigator of acquisition. As partially told on the IAS website, and more fully told by George Dyson in a talk at DR Greenway, Veblen convinced the early Institute leadership to acquire the land, then did the legwork necessary to bring all the parcels together. Over ten years, beginning in 1936, Veblen laid the foundation for open space in Princeton, with the acquisition not only of the Institute lands but also the 100 acres on the east side of Princeton that he and his wife Elizabeth later donated as Princeton's and Mercer County's first nature preserve, Herrontown Woods.

It's interesting to look at the chronology of open space initiatives in the Princeton area. The Institute lands were acquired between 1936 and 1945. In 1949, the Stonybrook Millstone Watershed Association was formed. Around 1959 Herrontown Woods was officially opened. In 1969, the Friends of Princeton Open Space came into being. In 1989, the DR Greenway was formed. Whether there's meaning in the 20 year increments of their foundings, all three nonprofits played a role in purchasing from the IAS the conservation easement that now protects the Institute lands from development.

Preservation tends to be celebrated more than management, so it's good to see there's a plaque celebrating maintenance, at least of the trails. The leadership and persistence needed to keep the woods accessible was first provided by Veblen, then later by mathematician Paul Dirac, then still later by what appears to be lasting funding in 2008 provided by Addie and Harold Broitman.  

Though the land is preserved, and the trails continue to be kept clear, and the richness of the Institute Woods has been researched and documented by Henry Horn and others, there is still a missing element for insuring the Institute Woods' longterm health. It's not clear that the woods hold the same biological richness seen in Veblen's time, or even Henry Horn's. With habitat restoration and deer management, we might lose the colors of the second forest, but gain a second preservation, this time saving the flora and fauna not from developers but from ecological imbalance and attrition of native species over time. 

The first preservation, in 1997, prevented intentional alteration of the woods by developers. But the woods is still being altered indirectly, unintentionally, through the invasion of introduced species and the banishing of predators that once kept deer numbers in check. The second preservation takes responsibility for the unintentional changes humanity has unleashed, and requires us to be active and informed participants in the forest's ecology. Clearing the invasive species that crowd the forest, and reducing the intense browsing pressure of deer, would begin to bring back the lovely vistas and sweeps of wildflowers that surely helped inspire the community investment in saving the land more than twenty years ago.