Sunday, September 17, 2023

Last Chance to Pull Stiltgrass

This week and maybe next are your last chance this year to pull stiltgrass (Microstegium vimineum). This mega-invasive is an annual, so the logic of countering its spread is to pull it before it can produce and drop seed. If the seeds haven't loosened yet at the end of the stalk, you can still pull it. Throw it in the trash, or if there's a lot, make a big pile of it so that any seeds that sprout the next year will all be in one place and easily covered or pulled. Definitely don't put it in your compost if its seeds are forming. If stiltgrass is just starting to invade your yard, pulling as completely as possible now will greatly limit its seedbank for next spring. Another strategy for large stands is to let the stiltgrass grow, then just as it begins to flower mow it short and hope its feeble roots don't have enough energy to grow another flowering stalk. 

For those fuzzy on identification, google lots of images, and look for the silver line running down the middle of the leaf. Stiltgrass can grow in the shade or sun, climb up to four feet, or thrive in a miniature state while ducking below your mower in the lawn. It's incredible survival skills include being incredibly inedible for wildlife. Stiltgrass gives nothing back to the habitats it increasingly dominates.

More on Stiltgrass, and a Success Story

Walking in the local woods, you've probably seen this kind of scene--what looks like a grassy meadow extending through the forest. In the filtered light of the understory, its simplicity and lushness may have some visual appeal. And yet, in some ways what you are looking at is the ecological equivalent of an urban food desert. 

Stiltgrass is an introduced plant that could be called a pervasive invasive, able to thrive most anywhere and dominate whole landscapes. Its success has come in part through being inedible. As wildlife selectively eat native vegetation, the stiltgrass expands, preventing the native plants from rebounding.

Unlike another nonnative annual weed that can look similar, crabgrass, stiltgrass becomes ubiquitous because it can thrive in sun or shade. That means the stiltgrass invading your lawn and flower beds can continue spreading ad nauseum into the nearby forest, or vice versa.

We used to call it bamboo grass--something in the shape of the leaves is reminiscent. The stiltgrass name refers to its angular growth, with each segment supporting the next as it climbs up and over fallen logs and other plants. Packing grass is another common name, referring to how it was once used to pack porcelain for shipment. That's probably how it first reached the U.S., in packing crates sent to Tennessee. 

When I first encountered it, growing on the bank of Ellerbe Creek in Durham, NC, I thought it graceful. Then came Hurricane Fran, bringing floods and fallen trees. In the aftermath of that massive disturbance, stiltgrass exploded in the landscape, expanding and ultimately choking forests with its vast, dense stands. New Jersey proved no different. 

Stiltgrass tends to establish itself along roadsides. Here it is growing in a green ribbon along Herrontown Road. Trails, too, provide an avenue for extending its reach, its tiny seeds carried on boots or the hooves of deer.

Though stiltgrass has covered large areas of woodland in the eastern U.S., we have found it worthwhile and even satisfying to counter its relentless incursions. Today in the Barden at Herrontown Woods, some volunteers pulled it out of a patch of native jewelweed along the edge of the parking lot. 

Nearby, on land where we have largely eliminated a massive clone of wisteria, stiltgrass was starting to move into the void. If nothing were done, this open woodland would have become a pasture of stiltgrass. But we have acted early enough to be able to remove all of this year's stiltgrass, dramatically reducing the seeds available for next year's crop. This photo shows the last patch before we pulled it. 

Interestingly, there are native grasses that look a little like stiltgrass, the main one being Virginia cutgrass (white grass), Leersia virginica. It has longer, narrower leaves that lack the silver stripe down the middle. As is a common ecological refrain, the native grasses "play well with others," not forming stiltgrass's massive, exclusionary stands. Some smartweeds like Lady's Thumb can also bear a resemblance. 

Saturday, September 16, 2023

Where Have All the Spotted Lanternflies Gone?

Well, it's happened, at least in our neck of the woods.

Billed as a major calamity, the spotted lanterfly invasion has gone "poof" this year. Yes, the spotted nymphs could still be found clinging to the stems of Ailanthus sprouts at our Barden in Herrontown Woods. 
And a few adults were later seen perched on the rachis of Ailanthus leaves. We pulled the sprouts out of the ground to deprive them of this haven. Hard to say where they went after that.

Writing a post about lanternflies three years ago, I learned that numbers of the invasive insect had dropped in some areas of Pennsylvania five years after first being seen. Lanternflies first showed up in Princeton in 2018, and here we are five years later, with what appears to be a dramatic drop in numbers.
It's true that people gave themselves over to squashing the pesky bugs--leafhoppers, actually--in spirited ways. (This photo shows one of the more creative approaches.) Some think the unusual weather has had an effect. Insect numbers overall have been down, be it the pollinators on backyard flowers, the odorous house ants that used to invade our kitchen, or spotted lanternflies. But my guess is that it has been the full-time predators, feathered or with eight legs or six, that are to be most congratulated for stemming the explosion of spotted lanternflies. 
Just follow the trail of colorful wings that brightened a walk up towards Veblen House one day.

The most powerful contrast for me is between the invasions of emerald ash borer and spotted lanternfly. Since the emerald ashborer arrived, about ten years ago, I have yet to see a single adult ash borer in Princeton, and yet the devastation they have brought to the ash tree is all around us. The lanterfly, on the other hand, has been seen everywhere, and yet I can't point to a single plant that has died due to their appetites. We humans are visually oriented, but it's the invisible threats--be they an invasive insect or even more significantly an overdose of carbon dioxide--that most endanger our world.

Thursday, September 14, 2023

Yew Berries and Dewberries


I've passed by this yew hedge on busy North Harrison Street thousands of times, and usually pay it no mind.  

But a couple days ago, I happened to be looking down at the sidewalk rather than the gazillion cars and trucks driving by, and saw something that caught my eye.

Yew berries! They look like small, bright red pitted olives, but the pit is definitely still there. Fifty years ago, in botany class, I learned that the juicy red part is edible, but the hard central pit is most definitely not. The side of a busy street is probably not the best place to be harvesting edibles, but I picked a few, ate the flesh and spit out the pit--an unexpected treat along a sidewalk in Princeton 

Technically, the yew berry is not a berry at all, but
an aril. All students of botany will vividly remember the moment in class when they learned that, as one website states, "in contrast to a berry, which develops from the ovary, an aril is an outgrowth of the ovule, or of the funicle which attaches it to the placenta." Botany is full of surprises.

The yew we sometimes see planted around houses is one of the few conifers native to England, according to the Kew Gardens website. America has a native yew, Taxus canadensis, which shows up on a 1960s plant inventory for Herrontown Woods, but I've never encountered it. 


One thing I discovered this year is that we have dewberries growing in the Barden at Herrontown Woods. I had thought we had three types of brambles in the Barden: blackberries, black raspberries, and the nonnative wineberries. But some of the blackberry-like plants were crawling along the ground rather than arching upwards, as brambles are more normally wont to do. These we decided were dewberries. They still have thorns, but you could say they lack spine. The whole concept of a dewberry was likable, from its less intimidating presence to the promise of fruit. They are very adventurous in some areas of the Barden, however, crawling long distances. We may need to curb their travels, even though the berries, ripening in mid-August, are pretty tasty.

Thursday, September 07, 2023

Pilewort--A Native Weed With Hidden Flowers and Showy Seeds

Some plants have it all backward. Flowers are supposed to provide the show; the seeds, not so much. 

But with pilewort, its the seeds that catch the eye, clustered in raggedy bunches that look like cotton. 

The plant sets up great expectations as it grows and grows, fleshy like a large thistle, but soft and approachable, 

with a pleasant scent when you crush the leaves. What fabulous flowers will crown all this vertical ambition? 

Something looking like a flower bud appears, but it never generates anything resembling a flower with petals. Pollinators visit nonetheless, even though the flowers look like duds. 

During our monthly nature walk at Herrontown Woods this past Sunday, I was grateful that one of the participants pointed out some other activity around the pilewort flowers. A common local ant species was busy tending to a flock of aphids sucking juice from the stems. The ants harvest the aphids' honeydew. 

Pilewort (good luck with the latin name, Erechtites hieraciifolius) is what I call a native weed. They pop up in large numbers in areas that have been disturbed, rising 8 feet high in what looks like a fleshy forest dusted with snow. 

Maybe the name comes from the piles of seeds it deposits all around. Another common name for it is fireweed, because it sprouts abundantly after a fire has swept through.

You might think this plant a menace that will take over. The nonnative lambsquarters, also an annual, can give this impression too, growing densely and tall the first year after a disturbance. But I've learned not to be concerned over their dominant presence. The first year's show of abundance fades in subsequent years until you can hardly find a one. Other plants move in, and pilewort awaits the next disturbance. 

Tuesday, September 05, 2023

Obedient Plant: Big Pink in a Season of Yellows

Among sun-loving native flowers of summer, the so-called obedient plant shows up all fresh and fulgent just as the party is starting to wind down. Each year it catches me by surprise with its pink when so many other flowers--sunflowers, cutleaf coneflowers, Silphiums, Heleniums--go with yellow. 

Obedient plant (Physostegia virginiana) is also off my radar because it is risky to plant. Its tubular flowers may obediently remain sideways if you push them, but the plant itself spreads aggressively underground. Not surprisingly, it's in the mint family, known for roots that spread hither and yon.

That's why this gardener on Grover Ave was so smart to plant it between a sidewalk and the road, where its capacity to spread is limited.

A similar strategy to curb its spread was used in front of Jay's Bike Shop. 

Obedient plant also pops up in several spots in Herrontown Woods each summer. Hard to say if it was planted or part of the indigenous flora. Interestingly, it doesn't seem to spread much when in an open woodland rather than a garden. Many other species that seem modest, even rare in the wild--various native sunflowers, groundnut, virgin's bower, fringed loosestrife--also turn rampant when planted in the comparatively tame environs of a garden.