Invasive, moi?

The British are coming! The British are coming! Exploring the nature of native and invasive species, from the American East Coast

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Saint or sinner? The highly invasive Tree of Heaven

Where are you from?

On the surface, a simple question. In reality, for a lot of people, one loaded with complexity and nuance and, in the worst cases, prejudice. Accent, attire, complexion, can all spark curiosity or suspicion. 

What does it mean to belong to a place? What does it mean to be from somewhere? Or, as is usually the thrust of the question, to be from somewhere… else?

This is a question I’ve grappled with most of my life. My father is Spanish. But actually, my paternal family is Catalan (an important distinction). My mother is Argentine. But actually, she’s the daughter of Jewish migrants who fled persecution in Eastern Europe in the first half of the 20th century. I was born in London, and have lived in London my entire life (barring university term times spent in the Midlands), and yet when I travel to certain parts of the UK I feel like a complete outsider. For all sorts of reasons.

So I’m Spanish, but not, and Argentine, but not, and British, but not. Depending on who you ask. Always depending on who you ask. Different people will have different criteria to determine who or what I am: “Where were you born? Do you speak the language? Have you been?” 

Britain is home. It is where I was born, where I grew up, where I went to school, where I live, where I have started my own family. But do I belong? Am I native? And if not, to put it in plant terms, am I… invasive? 

I’m writing this from Long Island, New York, USA. These questions, of heritage and identity, of arrival and belonging, are deeply ingrained in the collective memory of this country and its inhabitants. It is a nation founded by immigrants, who arrived from far across the ocean to a promised land of opportunity in the New World. People with US-born ancestry going back several generations will still describe themselves as being Irish, Scottish, Dutch. There is a pride in this family history, with many making the pilgrimage back to little Hebridean hamlets to suck in the peaty air once breathed by their forebears.

And yet modern day migrants to the US – often crossing deserts rather than oceans, these days – are usually not granted the same opportunity to pursue their American dream. (Not to mention the fact that the true native Americans were terrorised and displaced by the early European settlers.) It is still the case in this country (and very many others), that some people feel that they have more of a right to be here than others, and that those others must be kept out or pushed out by any means necessary. 

What has any of this got to do with plants? Well, this is particularly on my mind right now because I’m aware that in horticultural and conservation circles here in the US, there is also a major emphasis on native versus non native – aka invasive – species. 

A few days ago, our friends were kind enough to collect us from JFK airport. We loaded our luggage into their car and hit the highway, back to their home on Long Island. We made the trip at rush hour, which caused a frustrating extension on our travel time, but gave us an opportunity at least to take in the trees and shrubs of the roadside scrub. 

At first, I was so pleased to see what I thought was an abundance of one of my all-time favourite trees: the staghorn sumac (Rhus typhina). And yes, many of these trees, some already bearing their fuzzy pyramids of spicy seed pods, line Interstate 495. But on closer inspection, most of the silhouettes of these distinctive trees didn’t seem quite right. Where there should have been the upright purple panicles of seeds, there was instead a cluster of Sycamore-esque helicopter pods. Later, on closer inspection, the leaflets lacked the serrated outlines of the staghorn sumac; they were straight and smooth. 

Eventually I realised that the clusters of trees lining the highway verge; the saplings springing up between the metal rail of the central reservation; the two foot high shrub infiltrating the raspberry canes of our friends’ veg patch; the adolescent specimens disrupting the symmetry of the hydrangeas in the opposite neighbour’s front yard; all of these were actually Ailanthus altissima, more commonly known as Tree of Heaven. “Native” to China, Tree of Heaven is considered a highly “invasive” non-native species in many parts of the world, including here in New York State. 

A Tree of Heaven sapling (front and centre) infiltrating our friends’ raspberry patch

And it’s easy to see why. It is everywhere. And everywhere that something else – some native species – is not. And here on Long Island, like the holiday-makers, second-homers and city escapees, it takes advantage of the road network – specifically its disturbed verges – to travel, and travel fast. 

This can, of course, pose genuine problems. Not so much to humans – for all of the horror stories about kudzu enveloping entire towns, or Japanese knotweed (also, by the way, visible all over the place here on Long Island) breaking through concrete slabs and dislodging the foundations of people’s homes. No, we’ll be just fine. But just as the conquistadors and colonists made the continental United States unlivable for its indigenous population, so too these foreign floral invaders (always, of course, introduced by the movement of people) can disrupt or even destroy delicate existing ecosystems. 

In this context, it seems to make total sense to raise the ramparts, and prevent the surging tide of Tree of Heaven from drowning out beautiful native trees like the staghorn sumac, black walnut and (another personal favourite) the honey locust. I can see the bumper-sticker slogans now: “Local plants for local people!” “Build the wall!”

There is something about the tone of the conservation conversation that I find uncomfortable. (And it’s not just me: the excellent newsletter Radicle has published some excellent articles on this theme.)

Don’t get me wrong, it is vitally important to protect fragile habitats and their inhabitants from being wiped off the face of the planet, and many of these habitats are constructed upon a very exact configuration of species which have evolved together over a period of millennia. Even a small imbalance can be disastrous. And any time any plant or creature is lost for good, it is a tragedy. 

A thicket of Japanese knotweed makes itself at home on Long Island, under the airy canopy of a Tree of Heaven

But really, a fast-growing forest of Tree of Heaven on the side of a motorway isn’t responsible for the demise of native species, of shrubs or bugs or bigger animals. No, it is always, always, the actions of us humans, with our unrelenting insistence on desecrating wild places, and laying a destructive trail of tarmac and concrete everywhere we go, that has done, and continues to do, the real damage. Plants are all too often the scapegoats for our transgressions. 

It isn’t that it’s problematic to want to protect native species, but nor is it always commendable to do so. Often, introduced species are not so much driving native ones out, as they are filling the gaps and occupying the spaces where the native species can’t or won’t go: disturbed patches of land on the peripheries of our civilised environments; sandy, salt-swept stretches of coastline; or our highly cultivated, highly artificial back yards. 

All of which brings me back to here, now, looking across across the flat, glassy water of the Long Island Sound across to Connecticut. It’s difficult to avoid making the comparison between native/immigrant/invasive plants and native/immigrant/invasive people. 

Yes, some people, some plants, were here before others, but does that necessarily give them more right to call a place home? And if time – history, heritage, branches on a family tree – is the qualifying factor of nativeness, then how far back do you have to go? Many of our locally familiar plants have been with us for centuries, but were nonetheless introduced by earlier periods of human migration, exploration and expansion. Who gets to decide who or what is native? Who or what gets to call a place home?

As our climate continues to change, many native plants will struggle to keep up with the changing conditions. When that happens, introduced plants will be waiting on the wings to take their place. We may yet come to depend on these robust, resilient immigrants. We may mourn what we’ve lost, but will no doubt come to love and appreciate whatever survives: a new Eden, perhaps, where the streets are lined with Tree of Heaven.

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How do you feel about Tree of Heaven, Japanese knotweed & Co? Do you disagree with anything I’ve said? Whatever your view, please do leave a comment and let me know. I love hearing from you, and will always respond. Thanks for reading, and see you next time!