Wednesday, September 28, 2022

September Nature Vignettes

 Encounters with nature and sustainability around Princeton in September.

One of my favorite corners in Princeton is near the middle school, at Guyot and Ewing. It's a small enclave, a triangle of sense, where the yards and the roofs of houses actually perform work, growing food and gathering energy. On one side is a small house with a small yard that the owner has turned into an orchard and vineyard, as might be more often encountered in Italy. 

Nearby is a house whose south-facing roof has been completely covered with solar panels for 20 years. 

When a house was torn down recently at the corner, I feared it would be replaced with something huge and unattractive, 

but instead, a one-story house with extra thick insulated walls and solar panels and interesting design is taking form. It was a real surprise to see a one-story house being replaced with another one-story house that is sensitive to the history of the site and seeking to fit in, while showing off a modern design that seeks to minimize energy consumption.

They even have a sign on the fence describing the project and what was there back in Princeton's agrarian era. 

Blooming along the fenceline next to the house are sunflowers and autumn clematis vine. Gorgeous as they are, thankfully generating color at a time when most flowers are spent, they are best not planted in a garden unless where the spread of their roots is limited by a house or pavement. Otherwise, given abundant sun to power their aggressively spreading roots, they will take over your garden.

Another common encounter in September is with late-flowering thoroughwort, which spreads not by roots but by seed. It can be weedy but also lovely and even elegant at times, and is great for pollinators. I couldn't get myself to pull this one out in our backyard, even though it has completely taken over a garden path.
At the Barden in Herrontown Woods, they are so plentiful that we don't feel too bad pulling out the ones that lean over the pathways.

The fight against invasive species has the side benefit of taking me to areas of a nature preserve where I wouldn't otherwise go. Recently, it led me to a patch of native diversity in Herrotown Woods that I hadn't noticed before.

Here is obedient plant, 
New York ironweed, 
and the post-flowering look of water hemlock. 

One of my favorite garden plants this time of year is stonecrop "Autumn Joy." 

A sedum, its disks of flowers go through a gradual enrichment of color from green to pink to deepening shades of red, then finally chocolate. Nonnative but noninvasive, it has the added benefit of being popular with pollinators. 

Pawpaw trees are becoming more common in Princeton. The patches planted in Herrontown Woods have yet to bear, but this one in my backyard reflects a growing interest in this unusual species native to the north yet with a tropical taste.

Native persimmons, likely once common in Princeton but often shaded out by larger trees in recent decades, are an attractive smaller tree that might actually bear edible fruit if you happen to get a female and harvest it just at the right time.

If the drought hasn't made the berries too dry, these blackhaw berries could make for some good picking after they darken. Blackhaw viburnum, Viburnum prunifolium, is the most common native viburnum in our woodlands.

Less generating of anticipation are the fruits of a female ginkgo tree, encountered growing near the Princeton Junction train station. The fruits have such an unappealing smell that people try to avoid planting female trees. 

Among inedible fruits, I call this the incredible shrinking pokeweed, because it initially grew to be seven feet tall--way too big to grow along a busy street. So I cut it down midsummer and thought that was that, only to have it sprout back as a smaller version of itself. You could try this technique with a number of perennial native wildflowers that get too tall for people's taste. Cut them down partway through the summer, then let them grow back in a miniature form. 

Though it dies down to the ground each year like a perennial wildflower, pokeweed looks more like a miniature tree, and in fact it has a close relative in Argentina. The ombu grows to the size of a large tree, yet lacks xylem. 

This shrub, too, needs to be cut back. It's an oak-leafed hydrangea I planted long ago in a little raingarden at the front of the Whole Earth Center. The landlord the store leases from must have a new landscape firm taking care of the grounds, because I stopped by recently to find that my native shrubs have been trimmed to look like bowling balls. Funny to see a native shrub and wildflower planting getting the bowling ball treatment. I'll have to take some loppers to restore light to the window next time I stop by to buy some beets or delicious bread.

Sometimes, frequently in fact, I find myself wishing I wasn't right. Take this ash tree for instance, planted by the people who landscaped the new parking lot that Westminster Choir College built about ten years ago. I told them they needed to remove the ash trees they had just planted. The emerald ash borers are coming, and the trees won't survive. They left the trees in. The trees survived longer than I expected, but are finally succumbing. 

Actually, if you were trying to make Princeton sustainable, you might want to "farm" Princeton with smaller, short-lived trees that provide shade but are less expensive to take down. The above ground portions could be periodically harvested as a local energy source, and the roots left in the ground would sequester carbon. Trees are a source of solar energy, since they draw their carbon not from underground but from the atmosphere all around them. Thus, no net increase in atmospheric carbon from their combustion.

The landscaping for the parking lot also called for a raingarden to be planted here in this hollow. After being planted, the young river birch trees soon began to wither for lack of water. I assumed they would die, and that the raingarden would be poorly maintained and ultimately be mowed down. I was only half right. The river birch trees survived.

Here's what looks like a bright white flower that isn't. The white is the puffy seeds that give the plant its name. The flower seems not to open but remain in what looks like a bud stage. It's pilewort, a native weed that can reach seven feet tall.

Finally, a grass encountered in fields and local rights of way. When its flowers open and display their golden anthers, this native member of the tallgrass prairies can be eye-catching. Indian grass, Sorghastrum nutans, reminds me of the midwest prairies I used to help manage, and a time long ago when prairie openings were common in the east as well.

Monday, September 19, 2022

Do Praying Mantises Eat Monarch Butterflies?

It seemed like such a feel good moment, crossing the gas pipeline right of way out at Mountain Lakes. There's a lovely walk up from Mountain Lakes House towards Witherspoon Woods that crosses the treeless strip known as the gas pipeline right of way. 

The opening was enlivened by thistles in full bloom, probably native field thistles, if the whitish underside of the leaves is indicative. And adorning the thistles were multiple monarch butterflies, fluttering as they drank from the flowers. 

It had been years since I'd encountered a native thistle, and I hadn't seen a monarch in several weeks, so to see both together in numbers lifted the spirit. But the idyllic scene developed some disturbing undertones upon taking a closer look. 

There, down the stalk of the flower a little ways, something brown. Do you see it? A big praying mantis, of which there were several. I've long wondered if they could be one reason the monarchs are declining in numbers. 
The answer came quickly. A pair of monarch wings weren't moving, and there, sticking its head out, next to the lifeless remains was one of the praying mantises. 

Here's a clearer angle. 

The Intermixing of Good and Bad

My interest in plants began with organic gardening. When growing food is the objective, praise goes to rich soil and natural predators that eat insect pests. Once my interest turned to native diversity, however, my view of what was good began to change. I noticed that poor soil often harbored richly diverse native plant communities. Too many nutrients could be detrimental. And those natural predators that were keeping pests at bay? Well, the praying mantises we most commonly see are not natural, but were instead imported from China. 

Note: A National Geographic article explores how the praying mantis avoids being poisoned by the toxins in monarch butterflies.

All around the thistles was another invasive, Chinese bushclover, also known as sericea lespedeza or Lespedeza cuneata. I know it well from my years in North Carolina, where it was planted by the Dept. of Transportation as a supposedly good thing, to reduce soil erosion on newly carved road embankments. Proponents claimed its seeds would be a boon for wildlife. It has since become a major invasive pest in grasslands, replacing diverse native species with an inedible monoculture. And the seeds? Reportedly they are too small and pass through the guts of wildlife unutilized.
Its white flowers distinguish it from natives like slender bush clover (Lespedeza virginica), which has pink flowers and is rarely encountered. 
Chinese bushclover is a relatively new invasive in Princeton, but I've seen elsewhere what it can do, and it's only a matter of time before it forms monocultures to rival mugwort. There might have been a time when I would have praised it for its tough roots that hold the soil in place. Being a legume, it has the capacity to fix nitrogen from the atmosphere, enriching the soil. But no herbivore has come forward to limit its rampancy. From a plant diversity perspective, it is a disaster. 

The knowledge that all is not well in the world does not negate the delight in beautiful thistle blossoms and a clustering of monarchs. It just heightens the sense of positive and negative intertwined all around us.

Saturday, September 17, 2022

Stephen Hiltner Named Travel Journalist of the Year

First, I'd like to thank the Society of American Travel Writers for recognizing the achievements of someone whose name bears a striking resemblance to my own. It is with great humility that I accept, on behalf of all the Stephen Hiltners of the world, the giving of this award. Stephen Hiltners, from Ann Arbor to New York, with one stop in New Jersey, can take great and largely vicarious pride in this acknowledgment of worth. 

Sunday, September 11, 2022

Last Chance to Pull Stiltgrass

Late August and early September mark the last opportunity to pull Japanese stiltgrass before it goes to seed. An annual grass that was introduced from Asia, and which wildlife show no interest in eating, stiltgrass has taken over large swaths of the forest understory in Princeton, as well as many yards.  We called it bamboo grass when we first noticed it in the 1990s, back when I was living in the piedmont of North Carolina. It was also called packing grass, because it had in the past been used to pack porcelain coming from Asia. That's probably how it got a foothold in the U.S. 

The stiltgrass name fits when it extends it seedheads this time of year, appearing to climb up and over other vegetation, as if on stilts. Height tends to be around 2-4 feet, though it can even spread into lawns and somehow survive and reproduce as a miniature version a few inches high.

In late summer in the forest, it looks like this, ready to flower, bear abundant seed, then die. This is actually one of the smaller patches. In some invaded areas, stiltgrass extends through the forest as far as the eye can see.

In late summer, stiltgrass can form monocultures along wooded roadsides, thriving on the extra runoff from the pavement. 

Many people assume that since stiltgrass is so widespread, nothing can be done other than to wait a few hundred or thousand years for something to evolve to prey upon it and bring its numbers into balance with all the other kinds of plants currently drowning beneath this inedible green wave of supergrowth.

But there are many areas of Princeton where stiltgrass is just beginning to invade. Many yards still don't have it, or have small enough amounts to pull. Being an annual with weak roots, it is very easy to pull, and satisfying progress can be made if you have a small patch or many hands.

My strategy is to pick my spots, preferably pull it by late August, before it begins to flower, and just leave it on the ground to dry out. But even in September it can be pulled before the seeds begin to fall off. If it is already blooming and forming seeds, then either bag the pullings for the trash or, if you don't want to add to the landfill, pile it in one spot where any seedlings next year will be concentrated and easily dealt with.

We have made considerable progress in diminishing its presence at the Botanical Art Garden in Herrontown Woods, simply through persistent pulling to markedly reduce the production of seed. 

A friend at the NC Botanical Garden has found that large patches of stiltgrass can be treated effectively, before seed production, with a very dilute (0.5 %) solution of herbicide. Annual plants don't invest much in roots, and stiltgrass's weak root structure makes it more susceptible to systemic herbicide than perennial plants that may be interspersed. 

Here's what it looks like when it's going to seed. Stiltgrass seedheads look a bit like crabgrass, which is also an introduced annual that gets a late start in the spring and then seeds in late summer. What makes stiltgrass an aggressive invader of woodlands is its capacity to thrive both in sun and shade. 

On a recent walk along the Princeton ridge in Herrontown Woods, I found stiltgrass fairly early in its invasion, just beginning to form sizable patches.  Interspersed was a native grass with similar appearance--Virginia cutgrass--and it's interesting to note that the native grass, while common, does not form the large, exclusionary patches that the introduced species does. 

It's a challenge to tell the two apart. Most homeowner's yards won't have the native Virginia cutgrass, but it's interesting to compare. Here is Japanese stiltgrass, which also goes by the latin name Microstegium vimineum.
Here is Virginia cutgrass (Leersia virginica), with its longer, narrower leaves and more spread-out seedhead. 
Stiltgrass leaves often have a stripe down the middle.
Virginia cutgrass does not.

Once you start taking a closer look at the grasses along the ridge, you may notice the subtle differences between one species and another. Here's a native grass that I haven't learned the name of as yet. You can see that it has dense clusters of short leaves, in contrast to the others.

A look-alike homeowners are more likely to see is a nonnative smartweed called "lady's thumb," which has a cluster of pink flowers at the end. This photo shows lady's thumb at the bottom and stiltgrass growing up and to the left. Both are easy to pull.

Previous post on this subject: Stiltgrass's Annual Trillion Seed Initiative.