Shrubs and Vines to Cut Back Along Nature Trails

Without volunteers wielding clippers and loppers, most trails in Princeton would quickly become overgrown. Some preserves, like Mountain Lakes, Herrontown Woods and Autumn Hill Reservation, have more organized maintenance, but in some others it's catch as catch can. In May and June, that first flush of growth begins reaching out over trails, and so a pair of clippers is handy to keep in the back pocket during a hike. Cutting back anything that overhangs a trail is useful, but as a botanist I'm also identifying as I go along. Most of the shrubs that grow out into trails are invasive species that we'd want to cut wherever they are growing, but especially along trails. There are also some natives, but I'll start with the non-natives, which are so numerous mostly because the deer won't eat them. 

Privet -- A shrub that people plant as hedges, but which has spread into nature preserves, establishing dense stands. In low, wet, shaded areas, there can be thousands and thousands of these, claiming all the space. Most don't bloom because they are too shaded.

Here's a typical branch of privet growing out over a trail. 

Linden Viburnum has become highly invasive, forming dense stands. It has attractive flowers and fall color, but is just way too aggressive. It looks a lot like the native arrowwood Viburnum (V. dentatum), which is relatively rare and has more deeply toothed leaves. 

We commonly call this shrub Photinia, after its latin name. You can identify it by its distinctive obovate leaves, meaning the leaf is wider towards the tip. Names can get complicated in botany. The common name, which I just learned, is Christmas berry. The latin name was Photinia villosa, but that got changed to Pourthiaea villosa. Can you say "Pourthiaea"? Neither can I. In any case, it is another way-too aggressive nonnative shrub that we cut back or down.

This shrub, winged Euonymus, is super easy to identify. Just look for the "wings" on the stem (those brown ribs that run along the stem). It, too, is a nonnative that forms dense stands and often obscures what would otherwise be lovely vistas from the trail. If you see a nice vista from the trail, oftentimes it's because we've been cutting these shrubs down to open up the view. 

A common story about native plants in the wild: there's a native Euonymus, called Hearts-a-Bustin', but it's rarely seen because the deer love to eat it. We've nurtured a few specimens of it to show off at the Barden.

Bush honeysuckle -- Honeysuckle comes in the form of a vine (Japanese honeysuckle) and several species of shrub. it is frequently found along the edges of people's backyards--a sort of default vegetation that moves in on its own. It can also be numerous in some of Princeton's preserves.

Wineberry is an asian species of bramble with distinctively hairy reddish stems. It has tasty berries, but we often cut or pull it, given its lanky, thorny growth.

Autumn olive has a distinctive silver sheen on the underside of the leaves. While many invasive shrubs thrive in shade, autumn olive prefers sun, and so is infrequently encountered along our wooded trails.

Multiflora rose is an introduced species that has made many a forest impenetrable with its curved "fishhook" thorns. Multiflora means many flowers clustered together, as opposed to the single flowers that many roses have. We definitely cut this one back, or down to the ground, to keep hikers from getting snagged. 

Our native roses--at Herrontown Woods, that would be the very rarely encountered swamp rose--have single pink flowers, as opposed to the multiflora's clusters of white.

If you forgot your clippers, it's possible to avoid the thorns while carefully bending a young sprig like this one back on itself with your fingers until it snaps.

Two nonnative vines we pull out along trails are the Japanese honeysuckle 

and oriental bittersweet. Both are easily pulled out. For more success in pulling them out, grab low and pull slow. 

There are native versions of vine honeysuckle and bittersweet, but never encountered, as far as I know, in Herrontown Woods.

A common native along trails is sweetgum, which can grow into a statuesque tree but which we tend to cut or pull along trails, since its seedlings are so numerous.

The most common native shrub is blackhaw Viburnum, which has tasty berries in the fall. Sometimes it can be distinguished from other shrubs by its pairs of tiny leaves tucked in among the larger leaves, growing tight against the stems.

Another common native shrub is the spicebush, which has very fragrant, citrony leaves. 

Hickories are common as well. This is a photo of one leaf with five leaflets. 

I always feel some remorse while cutting native species back, but it has to be done if the trails are to remain clear.

Related post: Portrait of Sidewalk Neglect -- A post about plants that are growing over a neglected sidewalk.

Gently Enforcing the Gas Leafblower Ordinance

A couple days ago, I was doing some outdoor work when a landscape crew nearby revved up their gas-powered leafblowers. I put up with the din for about five minutes before finally heading over to tell them, in a nice way, that the town ordinance forbids the use of gas-powered leafblowers between May 16 and Sept. 30.

I got the crew's attention, then since they didn't speak english I explained in my broken spanish that "Hay una regla contra estas machinas hasta Octubre."

He nodded that he understood. I walked away only to hear them start back up a few minutes later. The situation was all the more frustrating because they were blowing leaves not off of a lawn but out of the woods, and because the leaves were soaking wet, it was going to take them forever to do what there was no rational reason to do in the first place. 

This time, I returned, didn't say a word, and photographed the machine and the address and the truck. He stopped again and got on his phone. 

I know the homeowners, and texted them about the situation. I could also have reported it to Access Princeton, but figured the problem was already solved.

You could hear that most wonderful silence as the birds continued to sing through the afternoon. My hat is off to the folks (Quiet Princeton?) who navigated the local political waters with a mixture of flattery and resolve to save us from these soul-sucking machines. (More info in the comment section about those who worked particularly hard to get the ordinance written and passed.)

Update, 6/15: Quiet Princeton informed me that a compliance officer has been hired by Princeton, so it is helpful to report violations to Access Princeton. Even if the non-compliance has been resolved at a particular residence, landscapers might try to continue using gas leafblowers elsewhere on their routes.

Happened to see a backpack electric leafblower at a nearby hardware store the other day. They at least exist.

Weeds that Launch an Underground Insurgency

More discussion of weeds here, after happening to see a great example of a particular category of weed--three different ones afflicting three gardens all in a row. It's important to know your weeds, because as soon as you find a plant that you like enough to put in your garden, there will be weeds ready to grow up it and over it and all around it. Catch them early and they won't be a problem.

A point that cannot be overstated is that a garden designer need only know the intended plants. A gardener--the one who gets dirty day to day realizing and maintaining some vision--must know not only the intended plants but all the other ones that pop up. To leave or to pull, that is the question. Being able to identify weeds empowers the gardener to take action. 

Many weeds will trick the inexperienced gardener. When first encountered, they may look pretty good, and seem pretty harmless, and so they get left to spread. Having gained advantage from our generosity, some of these deceptive weeds can become particularly tough customers, so that before you know it what could have been a small proactive pulling becomes a formidable task. 

 

Take this scene on Wiggins--one of my favorite streets because the houses are close to the street, encouraging gardening rather than a large, and largely useless, lawn. (Doesn't it seem like, starting with suburbanization in the 1950s, yards got bigger as people's knowledge of plants got smaller?) There are at least four of these gardens that caught my eye as I was riding by on my bike. One of the gardens is essentially weed-free, but I could see that the others, though they look okay right now, are each plagued by an underground insurgency.

Star of Bethlehem -- This first example of a weed's takeover will be least convincing for the reader. The white flowers of Star of Bethlehem set off the red tulips nicely. But despite its pretty name and pretty flowers, Star of Bethlehem's capacity to spread through a garden and pop up in the lawn (along with wild garlic, it springs up early in the spring to form something I call "lawn blotch") has made it less than loved. 

Bindweed -- Another garden has some standard ornamentals--iris, purple coneflowers--and what at first glance appears to be a nice groundcover. 

But that groundcover turns out to be bindweed. Firmly entrenched underground, it is just starting its quiet insurrection that will smother the garden as the season progresses.

Canada thistle -- One side of the third garden has been completely taken over by Canada thistle, which might better be called spreading thistle, since it's from Europe rather than Canada. Many a garden and field has been invaded by this plant. 

Here, for instance, is a garden where the landscapers spread that pretty black mulch that has become popular, but underground was a whole network of Canada thistle roots from which has sprung this year's crop. It will be impossible to garden this area.

Both bindweed and Canada thistle pull easily when the soil is moist, but that easy pulling is deceptive, as the underground root system remains undisturbed and ready to send up new shoots as soon as the gardener's attention turns elsewhere. A grasslike weed called nutsedge is also deceptively easy to pull. (Searching this blog for the word "nutsedge" pulls up some additional posts on weeds.)

Among the less common underground spreaders, in my own garden, I added two native vines--groundnut and Virgin's Bower (Clematis virginiana)--that have some wonderful qualities but turn out to be aggressive underground spreaders under sunny conditions. Autumn clematis--a nonnative very similar to Virgin's Bower--also can be super aggressive underground. And then there are the perennial sunflowers, and many kinds of mint. Native or not, they too establish large sprawling underground root systems that send up lots of new shoots the next year in places you really don't want them. 

A satisfying garden, just like a satisfying habitat, is a conversation among many species of plants. I like to think of myself as a moderator, and though I have a general vision for how the "discussion" will go, I don't have the time or inclination to exert strict control. When one species of plant takes over, the feeling is much like someone who takes over a conversation. There's a narcissistic quality to an aggressive plant, a Me, Me, Me indifference to what other species have to contribute. Dominance by one species has ecological impacts as well. Loss of plant diversity strips a habitat of the progression of blooms that might otherwise sustain pollinators through the summer and feed a diversity of herbivores. 

What to do about aggressive underground spreaders? One can play a war of attrition, in which the vigilant gardener deprives the underground root system of energy by pulling all shoots as soon as they emerge. Over time, the root system, needing to continually burn energy in order to survive, exhausts itself for lack of energy inputs from above. Since vigilance is hard to maintain, a more sure approach is to lay cardboard over the whole thing, cover the cardboard with mulch, and wait a year. 

Both of these approaches can help, but neither is very practical in most situations. For our own bodies, we sometimes need to take medicine to knock out a pathogen. The same holds true in a garden, where some careful spot-spraying with a systemic herbicide can kill the entrenched root systems of these underground insurgencies. Again, this is a minimalist, medicinal use of herbicide, not the chemical treadmill often aimed at asserting total control over nature.

The work involved in countering the aggressive spreaders makes the gardener really appreciate all the wildflowers that stay where you plant them. The aim is to get back to a garden where many kinds of plants coexist in relative harmony and balance. Catch the aggressive spreaders early, and gardening becomes much easier.

Mother's Day's Complicated History With Flowers

I was thinking, enough with the blog posts about invasive plants and weeds. Time again for some pretty flowers, especially since it's May, and Mother's Day is today. Wondering if flowers had long been part of the Mother's Day tradition, I looked up Mother's Day on wikipedia, and things got complicated fast. Though elsewhere in the world there had been Mothering Days when people were supposed to visit the Mother Church where they had been baptized, Mother's Day in the U.S. finally came into being through the initiative and persistence of Anna Jarvis. 

Following the carnage of the Civil War, and before Anna Jarvis entered the scene, there had been efforts to celebrate mothers as a force in the world for peaceful settlement of differences, but none of the events had evolved into a tradition. 

The death of Anna Jarvis's mother on the second Sunday in May, 1905, spurred Anna into action. Nine years of advocacy ultimately led to Woodrow Wilson's signature proclaiming an official Mother's Day in 1914, just in time for the outbreak of WWI several months later. Note the placement of the apostrophe. Rather than a celebration of mothers in general, Anna's vision was a very personal affair, in which people would give handwritten notes expressing gratitude for all that their own mothers had done for them. Anna distributed white carnations at the first formal Mother's Day event in 1908, but ultimately would spend the rest of her life fighting the commercialization of the day by the florist, card, and candy industries.

To honor the brave founder of the holiday, therefore, it looks like the best course of action would be to write a note of personal gratitude on something other than a Mother's Day gift card, perhaps accompanied by some flowers cut from the backyard. Lilacs, anyone? That could be followed by a stroll past some gardens with flowers in bloom.

Below are a random assortment of flowers that you might encounter, though the reader is to be discouraged from picking unless they are growing in your own yard.

A few from my own yard. This is Siberian bugloss, which is often confused with

forget-me-nots, which are paler, less robust, and have much smaller leaves.

Witch Alder (Fothergilla) is an attractive native shrub that I haven't seen growing naturally in our area but is available in nurseries.

At Herrontown Woods and other local preserves, you'll see lots of blackhaw Viburnums with lots of small disks of flowers. "Blackhaw" means black berry, which makes for a tasty treat in the fall. Flowering dogwoods, not shown, are also blooming in the woods and in people's yards now, with much larger, single flowers.

These native azaleas, nurtured in the Barden at Herrontown Woods, have probably popped open by now. An experienced gardener sees the full bloom even in partially opened flowers.

Up at the Veblen House, where the flora shift from native towards English garden, people ask what these pretty white or blue flowers are that spread across the lawn. Ajuga--a member of the mint family. Some people call it bugleweed.

Ever seen these and wondered what they were? So have I. Fritillarias have persisted in the Veblen garden from at least the 1970s, 

along with a few primrose. 

Some of these flowers may extend back to when Elizabeth Veblen was living there, pretty much on her own after Oswald died in 1960. 

In fact, there's no need for guesswork. Here's the same flower from a photo Oswald Veblen took in the 1950s.

Elizabeth had no children, but is best known for giving birth to the tradition of tea at the Institute for Advanced Study, and left her house and garden to the public trust. Her nickname was May. She and her husband gave us the month of May in Herrontown Woods--a beautiful thing--and all the other months as well. Our letters of thanks take many forms, including cutting back invasive shrubs and pulling weeds so these flowers can flourish once again. 

An Explosion of Spring Weeds

Ever heard of a painter whose spouse couldn't get him to paint the house? That's a bit like my backyard. While I've been doing plant work elsewhere this spring, my own backyard was quietly, stealthily taken over by an extraordinary array of spring weeds. The day of reckoning, or more likely several weeks of reckoning, has finally arrived. 

First step, photograph them and write about them, on the chance that others might too find themselves wading through a backyard full of weeds and wonder what they all are. Click on a photo to make it larger.

This one, the most ridiculously successful, is purple deadnettle. It's in the mint family, which you can tell by its square stem, but unlike many other mints, it relies on seeds to spread, rather than underground rhizomes.

Here's more purple deadnettle, with a foreground of ground ivy. Ground ivy has other names: creeping Charlie, and gill over the ground. It spreads vegetatively above ground, across lawns, into garden beds. It could be charming if it weren't so aggressive. The same can be said for mock strawberry.

Here's the ground ivy mixed in with some white clover at the bottom of the photo. The white clover hasn't been a problem, but in some situations, it too can become a sprawling mass.

Ground ivy looks like a wave here, rising out of the lawn and swamping the stonecrop Sedums. I really like the dandelions, until they go to seed, then not so much. If the soil is soft, gather all the basal leaves in your hand and give a slow, steady pull. Feed the leaves to your guinea pigs. Do people still have guinea pigs as pets?

By now, you'll recognize the ground ivy at the bottom of the photo, the purple dead nettle in the middle. Equally prevalent is hairy bittercress, which is the now brown plant in the upper left. A gardener feels a sense of defeat when, having delayed too long in pulling the hairy bittercress, its seeds come flying up at your face. It feels like mockery, the plant having successfully completed its life cycle and populated the ground with seeds for yet another year.

On the upper right in the photo are a few garlic mustards. They are edible, so I pull them, eat the seedheads, then toss the plant where it won't reroot. My yard would be full of them, too, if they were as stealthy and quick to generate seeds as the bittercress. Being larger than bittercress, garlic mustard is more satisfying to pull, and since it is slower to mature its seeds, we can go through a period of procrastination and still pull it in time. Garlic mustard is a biennial, meaning it grows some basal leaves the first year, building up energy in the root, then launches a flowering stalk the next spring. If not pulled, it will go to seed, then turn yellow and die in mid-summer, its work done. 

That's a different approach from many of these spring weeds--hairy bittercress, purple deadnettle, common chickweed, henbit, etc.--which sprout from their seeds in the fall, overwinter in the vegetative state, then get a quick start in the spring, blooming and setting seed before distracted people like me can pull them. 

At the top of this photo is hairy bittercress before it turns brown. On the left is Canada thistle, which has taken over many a garden bed in Princeton, spreading underground, popping up all over. I keep it at bay but have not been organized or persistent enough to fully get rid of it. 

At the bottom there are violet leaves. 

I'd like to say that the violets are less aggressive. They integrate into the lawn rather than taking it over, sprinkling attractive blooms hither and yon, and the leaves and flowers are good in salads, or steamed. But even they started being way too pushy in the flower beds a couple years ago, prompting a major weeding out. If salad makings weren't so easy to get in the local store, we'd be eating violet leaves, feeling just fine and with more balanced gardens to show for it.

Happy to say that I have no lesser celandine in my yard--the most problematic of the spring weeds, given its capacity to take over and then spread into the neighbor's yard and nature preserves. There was one in the yard a few years ago, but one medicinal spritz of herbicide was all it took to nip it in the bud. The leaves are reminiscent of violets, but are less curled, lighter green, and more leathery in appearance.

Mugwort, down there at the bottom, is a tough customer that has taken over many gardens, raingardens, and fields. Recurrent pulling has limited it to one place in my garden, but it spreads to form monocultures along the gas pipeline right of way along the Princeton ridge. Above and left in the photo is a kind of horsetail that has inculcated itself into one of the flower beds, probably planted decades ago by a previous owner.

I remember Veronica (speedwell) from my field botany days. It has an interesting bi-colored flower, and in our Michigan yard it had seemed harmless enough. When it showed up in our Princeton yard a few years ago, I let it grow here, but, perhaps due to a sunnier yard and abundant rains, 

it exploded this year and became, like so many problems in the world, too much of a good thing.

Chickweed hasn't been much of a problem. 

Curly dock is easy to undercut with a shovel. 

You see that little triplet of leaflets sticking out at the bottom? That's wild strawberry. I thought it would be great to have wild strawberries in the garden--native, tasty little berry. But they spread like crazy and I happened upon only one berry over the years.

Another weed that's here and there and can easily be pulled from wet ground is rough avens. To its left in the photo is a native weed called willow herb. Both of these look like they might generate attractive flowers, but don't quite generate enough show to be considered ornamental.

Wood sorrel, bottom of the photo, is a common greenhouse weed, but not much of an issue in a garden. Its leaves look somewhat like clover, but are tangy with the taste of oxalic acid.

The green leaves towards the top of the photo are jewelweed, a native annual that can be rambunctious, but which I appreciate for its tubular orange flowers that attract hummingbirds.

Most of these weeds originally hitchhiked to America from other continents. Finding early on as a gardener that most of my labors involved saving the intended plants from these overly enthusiastic weeds set the groundwork for understanding the problem of invasive species in nature preserves.

The reader may by now have concluded that my garden is largely a battleground where a distracted gardener is little match for weeds that grow 24/7. But there are areas where balance is easier to maintain, where celandine poppies, redbuds and dogwoods start a pleasing progression of flowers that continues through the spring. 

Lesser Celandine Alert!

It's time for the annual call to action to prevent lesser celandine from taking over all of Princeton. Also called fig buttercup, it's a highly invasive nonnative plant that is spreading rapidly, yard to yard and into parks and nature preserves, where it degrades habitat for wildlife. It thrives on homeowners' indifference and inaction, so I've been doing what I can, urging town officials to defend our parks and preserves, urging homeowners to take action in their own yards, explaining that herbicides are not anti-nature if they are used selectively and medicinally. My letter to the Town Topics and other local publications starts like this:

Blooming in many people’s yards right now is a small yellow flower that, upon closer inspection, proves not to be a dandelion. Variously called lesser celandine or fig buttercup, its radical invasiveness triggers a predictable progression of emotions in the homeowner. Delight at its pretty flower soon turns to alarm as year by year it takes over the yard, spreading through flower beds, across lawns and into neighboring properties. What may start as a few scattered, harmless-seeming clumps quickly becomes the equivalent of a rash upon the landscape. Unlike the dandelion, lesser celandine also spreads into nature preserves. Poisonous to wildlife, it forms thick stands reminiscent of pavement. Over time, our nature preserves become less and less edible to the wildlife they were meant to support. Native diversity shifts towards non-native monoculture.

Below are some photos to help with identification, and here is a link that includes suggested means of stopping it from taking over your yard. Though the link says only to spray through early April, I'd suggest that spraying is helpful for as long as its leaves are green. Lesser celandine is a spring ephemeral, meaning that it comes up early, then dies back in June, going dormant until the next spring. Gardeners who like to dig up plants of this or that to give to friends should be aware that, if their yards have been invaded by lesser celandine, some of it may hitchhike in whatever plants they dig up later in the season to give away. They may unwittingly be giving a fellow gardener the beginnings of a major headache.

Lesser celandine is poisonous, and yet some websites declare it edible and offer recipes. Why the contradiction? Apparently, lesser celandine accumulates toxins later in the spring. The toxins break down during cooking or after drying. Still, one takes one's chances trying to eat it, and, alas, wildlife don't cook.

I've seen bees collecting pollen and nectar from the flowers, which is all fine and good, but this doesn't compensate for the inedibility of the leaves. The invasion of our lands by nonnative plants that wildlife don't eat essentially shrinks the acreage of functional habitat in Princeton, even though a great deal of open space has been preserved. Thus the need for management.

Given that some areas of Princeton have been overrun by lesser celandine, it's important to defend those areas that have not, by closely monitoring and spot spraying where the plant is just starting to move in. Invasions begin with just a few plants here and there. An absolute minimum of herbicide is needed to easily defend these areas. Lesser celandine can easily be distinguished from dandelion. Walk the grounds before the grass gets mowed in the spring and while the plant is blooming. For lawns, a product like Weed B Gone works. For other areas, a 2% solution of glyphosate does the trick. Since glyphosate can take a week to show visible effect on the plant, it's best to spray early in the spring so that there's time to see results and spray any areas missed. For those near wetlands, wetland-safe formulations of glyphosate are available, so Roundup is not the only option.

In terms of aesthetics, lesser celandine's dense, exclusionary growth does to the landscape what people badly afflicted with narcissism do to social situations. A woodland that once hosted a diversity of native wildflowers becomes, when overwhelmed by lesser celandine, one species' declaration of Me! Me! Me! 

Here's what it looks like up close.

Here's an example of the blotchy appearance an early invasion creates on a lawn. These blotches expand until the whole yard is coated.

The closest lookalike in the lawn is the violet, whose leaves are darker, more curled, and more toothed along the edges.