Lawn Blotch 2024

Maybe people have another name for it, but every April there is a condition of some lawns that catches the eye. I call it "lawn blotch," which develops early in spring when the grass has yet to grow but other plants have.

Those other plants that spring forth here and there in a lawn might be Star of Bethlehem, which will later have pretty white flowers but spreads underground, popping up all over the place in your yard. 

Or they might be the pretty but terribly invasive lesser celandine,  which will become a nuisance for you, your neighbors, and your local nature preserve if you don't spray it or dig it up.

Or they could be a weedy allium that I call wild garlic. 

None of these plant species are native. Lesser celandine is poisonous. 

Lawn blotch has at least one positive, though. I've frequently seen the wild garlic being gratefully harvested by people of Asian heritage, to use in cooking like chives or onions. 

Lawn blotch as a phenomenon quickly passes, as the weather warms and the grass begins to grow, and lawn mowers once again impose a vertical conformity on the suburban landscape.

As an adendum, below is a fun quote from a post I wrote about lawn blotch eleven years ago. Though the climate has been changing considerably, lawn blotch still coincides with the Masters golf tournament: 

"As master golfers stride the perfectly groomed grounds of Augusta National this weekend, showing their mastery over a landscape that's kept in a perpetual state of arrested development, let us glance out the window for a moment at the less applauded realities of the suburban lawn. In the Masters tournament, only the hazards--the trees and shrubs--are allowed to reach maturity. For the golfer, any encounter with interesting plants is a sign of trouble. And in the yard, the main threat to calm conformity is the plant that seeks to lead a full life, by flowering and maturing its seed. (Full disclosure: I lettered in golf in high school, spent part of a summer mowing fairways, and probably developed a keen eye for plants while searching for lost balls in the nearby corn fields and the very rough rough of our neighborhood's rough-hewn golf course.)"

Central Park in Spring

Central Park back in April, where a glorious nature is framed by a Manhattan skyline, like a verdant postage stamp in the Forever series, 50 blocks long and 3 long blocks wide.

The land's mix of rock outcroppings and swamps, a desire to emulate parks in European countries, and a healthy dose of 20/20 foresight (short history here) all played a role in sparing this ground from economic imperatives, a place where nature can have its day, every day.

Central Park is ringed by museums of art and history, but Central Park's history is of the living sort, etched in infinite varieties of green and blue, enduring but ever changing, bottomless in its imagination, needing no roof other than the sky.

Spring migratory birds, shuttling like ambassadors between earth and sky, continent and continent, drew a crowd of admirers welcoming their return, cheering their journey, as if the birds were sailers just off the ship.

The warblers gobbled down proteins and energizing fat in the form of insects nourished by a patron oak's foliage,

while a raccoon's interest in the tree was more structural. Indifferent to our earthbound attention, it snoozed through the day in its high rise apartment (no elevator but rent controlled) in the crotch of the tree.

I could count on one hand, well, maybe two, my visits to Central Park, and yet it strikes deep chords within. Buildings are usually framed by nature, but in Central Park, its the buildings that do the framing. Get to know plants on a first name basis, and they will become like old friends you run into wherever you go. Central Park is like seeing an old friend all dressed up in a suit for the first time.

The habitat restoration being done along the trails of the Ramble are not yet Shakespearian in depth--Shakespearian here defined as the more you look, the more you see. But the restoration of expanses of native wildflowers, grasses, sedges and ferns on the forest floor is sufficient to trigger memories of the rich understory many eastern forests had just a few decades ago. Though ringed by concrete and highrise buildings, Central Park has in some ways a better chance to be natural than more rural areas thrown out of ecological balance by intense browsing pressure and unfettered invasive species.

I know of only one bluebell growing in Princeton's preserved open spaces. Central Park has many, protected from their primary threat, straying pedestrians.

A cool-season grass, presumably native, is being used on slopes for erosion control.

One reason why prospects are good for native plant restoration in Central Park is the vast pool of potential volunteers to draw on, given the auspicious ratio of NY's residents per acre of greenspace.

Not that one needs any additional evidence of the shear scale of human numbers in NY, but the Run-As-One fundraiser that day in Central Park drew 8000 participants, royally served by a row of Royal Flushes extending as far as the eye could see, that might rival some nearby buildings if stacked one upon another. Might this be an irreverent artist's vision of infinity?

How does one capture the scale of the operation, all of which must be periodically latched to stretched out trailers and hauled away for a bit of refreshing? Clearly, I digress, but then again, how many nature posts are thoughtful enough to provide a bathroom break midway through?

Segueing smoothly back into nature, here, a Fothergilla ornamenting some snazzy bins.

Park volunteers were spending a beautiful spring afternoon immersed in their own sort of marathon, pulling weeds, including the lesser celandine, that pretty but very rapidly spreading plant that had a post devoted to it earlier this spring.

The leader explained that herbicide use is not allowed in the park, so they're having to pull each lesser celandine individually. They showed me the tuberous roots. Pretty slow going, but fortunately, there isn't much of it in the park.

A few places in the park benefit from a thoughtful lack of intervention. These spent daffodils are being left unmowed so the post-bloom leaves have a chance to feed their roots for the next year.

There was some conspicuous smooching between a tree and boulder, familiar to anyone hiking the Sourlands or the Princeton Ridge. Nature has always thrived on an intimate relationship between the animate and the inanimate.

A gentle breeze propelled sailboats and memories of daysailer days.

Princeton has a couple of these Carolina bells (Halesia), one on Snowden, one on South Harrison. Strangely, almost no dogwoods were to be found in Central Park.

A frame within a frame, as nature, framed by the city, frames a sculpted shelter.

A grove of elm trees brings back memories of what American streets used to look like before Dutch elm disease swept through.

Leaving the park, we found Teddy Roosevelt in good company at the entryway to the Natural History Museum. Might he offer them horses as well? Looks like they're all trying to get back to the nature in Central Park.

Just inside the Natural History Museum, there appeared to be an allegorical confrontation between Truth and Towering Ignorance. Might Congress's high dome be accommodating something similar? Nice to see that T-rexian Truth had a nice set of choppers, though it wasn't clear who was going to win.

Lesser Celandine

Among invasive species, the most intimidating are not the giants like kudzu but instead the diminutive species that quietly multiply into millions, defying anyone to pull them all up. Lesser celandine, which has engulfed large areas at Pettoranello Gardens, cannot even be successfully pulled up, as each plant forms many bulblets underground that remain even if the plant itself is pulled. The species, which turns yellow this time of year as it goes into dormancy until next spring, continues to spread downstream into Mountain Lakes and beyond.

I've heard many testimonials from gardeners who love its yellow flower when it first shows up, then become distressed as it begins to take over the garden. Spraying with a low toxicity herbicide like 2% glyphosate (the active ingredient in Roundup) is the only way to get rid of it over time, unless one can cover it all up with a layer cake of cardboard and mulch when it first appears in the spring, robbing it of energy. Leave one plant, however, and the problem begins anew.

Lesser Celandine Blooming, But Mostly Spreading

 I wish I could go back to the first time I saw this flower and could appreciate its beauty without being worried it would take over all of Princeton. At Pettoranello Gardens it grows like green pavement next to the paths, blooms beautifully, but is radically invasive. Since becoming established at Pettoranello Gardens, it has spread downstream and has now become established in floodplains at Mountain Lakes Preserve. It displaces native plants, is apparently inedible to wildlife, and though it's pretty for a couple weeks, the rest of the time it's busy making natural areas less supportive of plant diversity and wildlife.

 In a suburban yard, it first appears as a couple plants, with small, roundish, shiny leaves.

It displaces the grass over time, then dies back in late spring to leave bare spots in the lawn. Its many underground bulbules make it hard to eradicate by pulling.

Lesser Celandine has started to show up in my former home of Durham, NC, where I've been trying to help eradicate small populations before they spread downstream.

Lawn Blotch

As master golfers stride the perfectly groomed grounds of Augusta National this weekend, showing their mastery over a landscape that's kept in a perpetual state of arrested development, let us glance out the window for a moment at the less applauded realities of the suburban lawn. In the Masters tournament, only the hazards--the trees and shrubs--are allowed to reach maturity. For the golfer, any encounter with interesting plants is a sign of trouble. And in the yard, the main threat to calm conformity is the plant that seeks to lead a full life, by flowering and maturing its seed. (Full disclosure: I lettered in golf in high school, spent part of a summer mowing fairways, and probably developed a keen eye for plants while searching for lost balls in the nearby corn fields and the very rough rough of our neighborhood's rough-hewn golf course.)

The grasslike imposter dotting the lawn in the first photo is Star of Bethlehem, which will later have a pretty white flower but tends to spread. It's in the lily family, is native to eastern Europe and the Middle East, and spreads to natural areas as well as across lawns.

Here's wild garlic, showing vertical aspirations far beyond the surrounding grass.

Blooming now, along with the dandelions, is Lesser Celandine. It shows up as one or two plants in a yard, then becomes more numerous each year until much of the lawn is displaced. Here's a new infestation, with maybe five plants or so. It would be easy at this point to dig it up, put the diggings in the trash (not the compost bin, where it will then be spread elsewhere), and avoid the takeover. But most people are seduced by its flowers when it first shows up, and don't grow alarmed by its aggressiveness until it's already become established.

Here's a more advanced example. You can type lesser celandine in the search box at the top of this webpage to see examples of it forming a green pavement in lowlands, apparently of no use to wildlife.

A related plant is Winter Aconite, which has dissected leaves and blooms much earlier in the spring. It spreads underground, but I've never seen it spread across lawns or invade natural areas. Both are non-native spring ephemerals that will turn brown in early summer.

Another spreader is Bermuda grass, which may originally have come from northern Africa and thereabouts. The photo contrasts Bermuda grass, which is a "warm season" grass that is still brown this time of year, with the "cool season" grasses such as fescue and ryegrass that are green in cool weather but suffer in the heat of summer. The owner of this lawn must have seeded a patch with Bermuda grass rather than the original cool season grasses.

The rhizomes/stolons/roots of Bermuda grass are so strong that they will spread into and break up asphalt over time. It is a very aggressive grass and hard to weed out of other plantings if it invades flower beds or natural areas.

This blotch-on-blotch effect of wild garlic sprouting up in Bermuda grass actually makes a nice contrast, though I'm not sure anyone would try to do it intentionally.

A modest proposal: One way to get rid of lawn blotch is to get rid of the lawn.

Fig Buttercup Alert--Little Flower, Big Problem

Yes, spring can be lovely, with some cheery displays of daffodils, and magnolia trees in their glory. But it's also an all too good time of year to witness with dismay and alarm the ongoing and accelerating invasion of the Princeton area by fig buttercup. Also known as lesser celandine, it's a small spring ephemeral that seduces with its pretty flower, then takes over your yard and garden.

It has already radically changed the spring landscape over in the Pettoranello Gardens and Mountain Avenue area, and I've watched it spreading from yard to yard over the past five years in my neighborhood near Hamilton Ave and Harrison Street.

These photos are from Maple Street just down from Nassau Street, where a still localized infestation is radiating out from one of the yards. A yard will have one or two plants the first year, dozens the next, quickly multiplying to hundreds and thousands. It's pretty easy to see whose yard was first by the density and extent of the invasion.

Across the street, the fig buttercup is taking over the lawn and flower beds.

The next door neighbor has an invasion in its earlier stages.

Why be concerned? There are many degrees and styles of invasiveness. I'll compare fig buttercup with other aggressive plants below, but here are the essentials: Fig buttercup is an introduced species that has escaped any limiting factors that may have been present where it evolved. It's poisonous, so nothing eats it. The seeds and the abundant underground tubers allow it to spread rapidly. It can grow in the sun or shade, garden or nature preserve.

Some gardeners may feel relief that, like other spring ephemerals, it will fade back into the ground after a couple months. But that seems small consolation as it increasingly displaces other plants that might otherwise grow.

By comparison, myrtle is a groundcover that people plant and may later regret as it takes over flower beds. But it doesn't spread down the street to ultimately pave the local watershed. It merely vexes the gardener who planted it.

By the same token, wisteria vine poses a much smaller threat than porcelainberry. Though an abandoned wisteria vine can spread over an acre or more, weakening trees and suppressing all other growth, it doesn't spread by seed, so remains localized. Porcelainberry is a vine that not only smothers all other vegetation, including trees, but also spreads to new locales by seed.

Most pesky weeds of the lawn--wild garlic, dandelion, false strawberry, ground ivy, etc--have not become problems in nature preserves because they are either edible to wildlife or intolerant of shade.

That's what makes invasives like fig buttercup and stiltgrass stand out as major threats. They spread rapidly, tolerate shade and a variety of soils, and nothing eats them. Since fig buttercup dominates in spring, and stiltgrass dominates in summer and fall, they represent a one-two punch that dominates the landscape visually, and leaves little chance for other herbaceous species to prosper. Since both are not eaten, yards and preserves become increasingly inedible for wildlife.

Fig buttercup can be confused with winter aconite, which also blooms early with a similar flower, but the leaves are much different. Though nonnative, I've never seen winter aconite spread beyond the limits of a yard.

This photo shows the native marsh marigold in the foreground, with leaves much larger than fig buttercup's, which is in the background. (For a closeup comparison of the two species, click on this link.) The marsh marigold, by the way, is very rare. I've seen it only a couple times in the wild. I planted the one in the photo, over at Pettoranello Gardens, purchased from Pinelands Nursery many years ago.

Click here for past posts about fig buttercup (lesser celandine), including a letter I wrote to the Town Topics two years ago that struck a nerve.

What to do? If there are just a few plants, you can dig them up and put them in the trash (not the compost), being careful not to leave any small underground tubers behind. But though I've had organic sympathies all my life, and don't like to use herbicides, the easiest way is to use a squirt of 2% glyphosate on the leaves (Roundup is the most common brand, but more generic forms are available), or else some herbicide more specific to broadleaf plants. We take medicines, and when used responsibly in a targeted manner, herbicide can play a similar role in nature.

Environmentalism has been too caught up in good vs. bad, when the biggest threat to nature and ultimately ourselves, whether it be carbon dioxide or a pretty little flower, is too much of a good thing.

Winter Aconite

One of the perks of buying an older home is what may pop up in the yard in the spring. Here are some winter aconites (Eranthis hyemalis), a long-blooming bulb that spreads around. They're much easier to see since the English Ivy was pulled out.
As with a number of other exotic species, it can spread in the garden, but doesn't seem to make the leap into local nature preserves, where it would not be welcome.
Don't confuse it with Lesser Celandine, which has become a seriously invasive weed, carpeting lowlands of Princeton preserves. They are in the same plant family (buttercups), and have similar flowers that open in late winter, but the leaves of Lesser Celandine are round.

Reading the Landscape Along the Towpath -- Early Spring

One place that gets a lot more interesting if you know plants is the towpath along the Delaware and Raritan Canal. For those into reading the landscape, the section just upstream of Harrison Street in Princeton makes for a good read, packed with history, beauty, poignancy, and the drama of invasion. 

First, there's the water, here with branches of elderberry reaching out over the canal in the foreground. Elderberry characteristically sprouts leaves earlier than other native shrubs. Water teaches the richness that reflection can bring to life. 

Along this stretch of towpath, the strip of land between the canal and Carnegie Lake widens, making enough room for a nature trail loop that for nearly 20 years has given hikers and joggers relief from the linearity of the towpath. Part of my life has been dedicated to making interesting destinations along very long trails, whether in Durham, NC or in Princeton. With a hardwired devotion to things, I've been an advocate for this little nature trail, and the unique, savanna-like habitat it winds through, since it was created nearly 20 years ago. Periodically stopping by to check that the trail hasn't been blocked by fallen trees, reading the landscape as I go, I always come away with a mix of joy, gratitude, and grief. 

Some flowers encountered during this walk are native, like this red maple reaching out over the trail.

Then there are some non-native species that fortunately aren't invasive, and speak to past intention. These photos were taken a week ago, when the ornamental cherries were just starting to pop. 

These really old ornamental cherry trees are reminiscent of those planted along the Potomac River in Washington, D.C. long ago. The cherry trees and the yellow spray of forsythia off in the distance show that this seemingly wild stretch of the towpath is actually populated with botanical remnants of another era, back when the university installed these plantings as an ornamental entryway to the campus. 

Adding to the evidence of past caretaking is a derelict row of winter honeysuckle (Lonicera fragrantissima), with very small, very early, and very fragrant flowers. Though it's included on invasive species lists, I've never seen it spread. 

If you're an environmental advocate at a local level, a walk can become a review of past successes and failures. For years, the DR Canal State Park, of which this ribbon of land is a part, would keep this nature loop mowed, but then their maintenance budgets started getting cut. Around the time one of their longtime mowing crew members died, they decided to turn mowing over to the landowners--Princeton University. That handoff happened at an administrative level, but not on the ground. After trying in vain to get the university to take care of the trail loop, I finally contacted Shana Weber at the PU sustainability office. Thankfully, she was able to reach the right people, and the trail is now being kept open. 

But one bit of mowing that the state parks people used to do has yet to be picked up by the university. And here's where the landscape's story shifts from joy and gratitude to grief. The nature trail loop winds through what for many years has been a savanna-like landscape of scattered trees and fields. Scattered trees allow enough sunlight to reach the ground to power a rich understory of wildflowers and shrubs. But due to a lack of annual mowing, that special landscape of forest openings, seldom found elsewhere, is being lost. Here is a forest opening that has become a layer cake of invasive plants, with multiflora rose blanketed by a web of super-aggressive porcelainberry vine. 

Other invasive vines also run rampant, like this Japanese honeysuckle smothering a branch.

Why is no one cutting the oriental bittersweet at the base of this tree, the wild gardener in me asks.

Many of the trees were planted, then ultimately abandoned, leaving a kind of derelict arboretum.

Some trees have succumbed altogether to introduced insects or disease, most commonly Emerald ash borer or bacterial leaf scorch. 

On the ground, the uber-invasive lesser celandine is laying a claim that will surely expand. 

Without annual mowing to sustain the forest openings, a tortured form of succession is underway, with sweetgum saplings being mobbed by the invasive vines. Annual mowing would sustain the special forest openings and reduce the smothering invasives.

A couple places where the native species are doing well are, not surprisingly, in standing water. Here's a rosette of a very healthy rose mallow hibiscus (Hibiscus moscheutos), its feet very much in water.

Here's a shrub that also flourishes in standing water, buttonbush (Cephalanthus occidentalis). 

There are lots of native plants that can thrive in floodplain habitats along the canal. If the university ever gets interested in habitat restoration, this would be a great place to start. It would be a high-visibility demonstration, to be witnessed by all the hikers, bicyclists, and joggers passing by, who currently see not the history and the ecological drama but just another stretch of green.