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. 

Finding Native Swamp Rose Amidst the Multiflora Rose

For those who need deadlines, the last cold days of spring are a prompt for action by a wild gardener. It's the last chance to get some work done in a nature preserve without having to worry about doing tick-checks. It's also a time when leaves have yet to dampen the light pouring into the forest, and the invasive shrubs are still in their less intimidating winter dormancy.

Scott Sillars and I took advantage of a cool afternoon this week to cut invasive multiflora rose and privet at Herrontown Woods. There is constant surprise in how this awkward, gutsy work is way more satisfying than it has any right to be. 

Though rose-rosette disease has reduced its rampancy, multiflora rose is still a highly invasive shrub in Princeton forests. With its gangly growth, the sprawling shrub can best be described as a blizzard of thorns, whose introduction from Asia long ago has rendered many forests impenetrable. 

Cutting it down, I'm always reminded of the many-armed "omnidroid" monster in The Incredibles movie. But the way to emerge unscathed from a multiflora rose cutting session is to be gentle and methodical. Cut enough of the gangly stems to gain access to the center of the shrub, then reach in to cut its multiple stems at the base. Extract yourself carefully from the situation, and if your heavy clothing (another advantage of cool weather) gets snagged by a thorn, rotate to loosen the fishhook thorns or cut the clinging stem so that it will fall off on its own. What seems like rough work is actually an opportunity to exercise finesse. 

Also, don't forget your work gloves, as I did one day.

Though there are thousands if not millions of multiflora rose growing in the preserve, the work does not seem futile. We pick our spots, in this case focusing on a route for a planned boardwalk from the parking lot up to Veblen House. 

Satisfaction is increased by encounters with native shrubs. Spicebush are fairly numerous, and the highbush blueberry in this photo is about to open its flowers. 

A surprising find was the native swamp rose. I almost cut it down before noticing its characteristic thorns, which come straight out from the stem. The lack of a fishhook shape makes them far less hazardous. 

At the base of the stem, the swamp rose's thorns become small and dense compared to multiflora rose. 

This is the third swamp rose I've discovered at Herrontown Woods and Autumn Hill Reservation. Their rarity compared to the countless numbers of nonnative multiflora rose speaks to their need for a more stable supply of moisture. Only where seepage prevents the soil from drying out do they survive. 

With this preparatory work, we hope to ultimately end up with an attractive and varied corridor for visitors to walk through, from stream to meadow to wetland--all part of a short walk up to Veblen House. 

Some Spring Sightings at Herrontown Woods

There's been lots of activity at Herrontown Woods over the past few weeks as nature begins to stir.

At last week's Sunday morning workday at the Barden (Botanical ARt garDEN), some middleschoolers really enjoyed picking the seeds of wild senna that had stayed on the stalks through the winter. This Sunday, we'll cut last year's stalks to make way for new growth.

Herrontown Woods caretaker Andrew Thornton discovered a bloodroot flower blooming just off the trail. Bloodroots and the very rare hepatica are early bloomers. March 20 for the bloodroot, which leads with the flower before generating a leaf.

Anyone who looks skyward at the Barden may see willow blossoms--one of the "keepers" we found amidst all the invasive shrubs cleared to create the Barden. The blooms of willows and red maples are an important food source for early stirring bees.

On warm, wet nights, salamanders navigate through the leaves to reach vernal pools to lay eggs for the next generation. Vernal means spring, as in vernal equinox.

Vernal pools are also the place for wood frogs to mate and lay eggs. Thanks to Lisa Boulanger, who took these two beautiful photos three weeks ago.

We first noticed our black vulture had returned on March 15. A pair of them raise their young each year in the corncrib near the Veblen Cottage. We used to think they were bad omens, but have gained respect for them as parents and for their ecological role in the community. 

Someone's been busy over the winter building a village in a little out of the way spot in Herrontown Woods. It appears to have avenues, skyscrapers, and some bricks that may represent schools or a hospital. Maybe it's a fort, given its walls. 

Coincidentally, public library staff are talking about doing a reading of the children's book Roxaboxen at the Barden in a month or two.

The boulders along the ridge are rounded, composed of diabase, which in my experience is associated with rare plant species that thrive in the particular kind of soil generated from the weathering of these rocks. The boulders were not deposited here by glaciers, but instead formed from molten upwellings from below. 

In Herrontown Woods and Autumn Hill Reservation there are numerous little abandoned quarries where some of the larger boulders were split into chunks and hauled away. 

Springtime is a great time to figure out where we need more stepping stones along trails. Because the rocks along the ridge are chunky and rounded--of no use for steps through muddy sections of trails--we make frequent trips to rock piles generated nearby, just off the ridge, where a developer has dug a basement. These conveniently flat stones are from the sedimentary deposits that the molten upwellings pushed through to create the ridge. 

One plant that doesn't look like much but which I've always been curious about is what is this low-growing grass. I call it soft fescue, and wonder if it was common long ago, and later became the first lawns around houses. Many old lawns still contain this mounded grass. Here's a patch of it growing along Herrontown Road.

At Veblen House, the remnants of Elizabeth Veblen's garden still cycle through the seasons, with sweeps of snowbells giving way this week to the many daffodils she spread across the grounds.