This 'Unruly Wild' scientist rejects calling plants invasive, says we should ask why some thrive

Juliet Stromberg sees plants as her friends. The retired Arizona State University researcher, plant ecologist and botanist loves climbing trees and she knows many of the ones on her property personally.

For the last quarter of a decade, she and her partner have been “rewilding” their property near South Mountain, restoring it into a lush, riparian landscape.

It’s the kind of effort you might assume uses only “native plants” in an effort to restore the desert back to its “natural” state. But, Stromberg is not a believer in the so-called native biology paradigm. She rejects the idea that some plants are “invasive” “alien invaders” to our ecosystems.

And, in her new book, "The Unruly Wild," she asks us to think about why certain plants arrive in our city or yards. And maybe welcome them.

It’s a reimagining of our relationship with the plant world, as she puts it. And it’s today’s deep dive. She told The Show she didn’t necessarily feel like she wanted to write this book, she felt like she needed to.

Full conversation

JULIET STROMBERG: I did feel like I needed to write this book, and that stems from a position of both science and and love. I'm a botanist and I love plants. I love the Earth's ecosystems, and I'm a scientist who likes to understand why things work. I've been studying the vegetation of the Southwest for, you know, four decades now.

And it just seems that the approach that land managers, conservationists, even some gardeners are taking are not benefiting the vegetation and the ecosystems, and in many cases what we're doing is harming. And so I wanted to challenge the current paradigm, which is based in sort of fear and control. The field of invasion biology is sort of is based in a war metaphor. And I just don't think the idea of going to war against plants is getting us what we want.

LAUREN GILGER: I've never thought about it that way, but it is. Like calling something an invasive species is like being saying you're being invaded by an army.

JULIET STROMBERG: Yes, the science of invasion biology is actually it's it's a science imbued with psychological warfare. And it's become so mainstream that we sort of forget that ecologists and botanists, conservationists did not always view the world this way.

It's a fairly recent development in a sense, I mean, in the 1990s is sort of when ecologists started and conservationists started using the term invasion, invasive species. And it's become deeply ingrained and it just seemed to me it's time for, uh, for some pushback, or for, let's change course a little bit and just examine, what in the world are we doing?

In 1999, President Clinton did sign this executive order on invasive species, which called for managers to not just control these so-called invasive species, but also to study them. And so during that quarter century, many new studies have come out, meta-analyses, sort of studies of studies, that are challenging some of the basic tenets of invasion biology.

And so I think part of me was saying this this science, this new science, needs to get out there. People need to understand that there is a there's a group of of scientists and conservationists that are saying this is kind of an outmoded way of looking at the world.

LAUREN GILGER: It's super interesting. So you're basically saying that an invasive species, like, you know, buffelgrass is a big one in Arizona, we hear a lot about, right? Or I keep thinking about stinknet, this invasive species is little yellow balls you're seeing pop up in your yard and all over the sides of roads, that it's being called an invasive species. Are you saying they're not bad for the environment here?

JULIET STROMBERG: Um, well, let me step back a second and say I really do not like to use the term. That label upfront shapes the way we're viewing the species. And I'm saying let's step away from that viewpoint and just say, here's a new plant that has arrived. Let's approach it with curiosity, with a maybe some degree of of respect, um, and just with an open mind.

Let's talk about oncosiphon. I like to call the plant globe chamomile, some people do call it stinknet. I think it smells great. So this it is a plant that arrived from South Africa not that long ago into the Valley. So it's a migrant. It's it's an immigrant species, and there have actually not been that many studies done about the plant. And yet, we're labeling it.

And the label invasive implies sort of ubiquitous harm, like naughty by nature some people say. And so that's like, that's a big strike against the plant. And then it's partly based in sort of fear, here's someone from the unknown, we don't know about it, it could harm us, and and then these ideas propagate.

It's just like a meme that propagates and suddenly everyone is hating this plant and fearing this plant instead of saying, OK, well, why is it here? Where is it growing? Let's understand it from an ecological point of view and from a less, um, fear-based standpoint.

LAUREEN GILGER: Right. We we might not condemn it if we understood why it came, what it could do here.

JULIET STROMBERG: Exactly. Open your mind to understanding why someone is here, kind of opens your heart to welcoming them here.

LAUREN GILGER: I think that's a wonderful thought. And I have definitely done segments on stinknet or globe chamomile. So I'm I'm completely guilty of this.

JULIET STROMBERG: Yeah, and and interestingly enough, basically what we're doing in cities, when we blow litter layers with our, you know, gas-powered leaf blowers, and we have irrigation structures that are creating little pockets of water year-round, we're basically we're creating ideal habitat for these disturbance-adapted ruderal-type species.

And when you go and try and clear them away and weed them out, you're basically just creating habitat for more of that type of plant. What we've seen in our own yard, because we've been rewilding a property of four acres for 25 years now, and during that time period, globe chamomile arrived in our property.

LAUREN GILGER: Right.

JULIET STROMBERG: And so we've seen other creatures adapt to it. We've seen what happens if we just leave it alone, because we don't remove it. It's just a little aster that is keeping the soil cool, it's feeding pollinators. And if we leave it alone, other plants like brittlebush will grow up, shade it out, and it's it's just coexisting with other members of the ecosystem.

LAUREN GILGER: That's fascinating. So there are it sounds like some examples lots of times in which you can you can document something that's known as a quote-unquote "invasive species" that's actually very helpful when it arrives in a new place.

JULIET STROMBERG: Yes. And one chapter of the book, I talk about this idea of the importance of environmental context and the phrase ecologists often use when someone asks them a question is they will say, "Oh, it depends." Um, and so if is the plant harmful? Well, it depends. It depends on where it's growing, what is the context, harm to who? And are there benefits accruing as well?

MARK BRODIE: That's Juliet Stromberg, a plant ecologist, botanist and author of the new book "The Unruly Wild" speaking to my cohost Lauren Gilger. We'll have more of their conversation in just a moment.

Good morning. It's The Show. And let's return now to our conversation with Juliet Stromberg, a plant ecologist, botanist, and author of the new book "The Unruly Wild." She spoke with my co-host, Lauren Gilger, about her somewhat controversial point of view rejecting the idea of invasive species in the plant world, and how she thinks about plants more as individuals than organisms.

LAUREN GILGER: So, I mean, I got to ask you, Juliet, because the way that you talk about plants and trees and the way that you write about them in the book is really remarkable from my point of view, right? Like you write about them like not only as living things, which they obviously are, but you write about them like as friends, like as sentient beings in a way that is really kind of striking. Tell us why.

JULIET STROMBERG: I guess there are a couple reasons for that. One, from a scientific perspective, there is much new research going on now about plant sentience and plant communication.

LAUREEN GILGER: Can they feel? Can they speak? Can they respond? Yeah.

JULIET STROMBERG: Exactly. So so there's this revolution going on in terms of how we're understanding plants. And, um, certainly they're sentient creatures. But there's also there is a a love connection with plants. And I trace that back to, I think, you know, being four years old and gardening with my mother and having her talk to the plants.

And so I started talking to the plants, and you formed a relationship with plants. And I think this lack of forming relationships with plants, and so many of us have become disconnected from nature and from plants because we many of us don't grow our own food anymore, it comes from the grocery store. We don't, um, make clothes from it, so so we're we've distanced ourselves from plants.

We have to make an effort now to to rebuild those relationships with plants. Um, and when I was a a scientist, those feelings were always there when I was an academic at ASU, but I maybe I suppressed them a little bit and viewed things that them as my study organism. ... And and now that I've been retired for eight years and it's like, OK, well, you can go back to being my friends now.

LAUREN GILGER: So I mean, as you mentioned, you have been rewilding, as you call it, this this property where your home is near South Mountain in south Phoenix and and turned it into sort of this incredibly lush desert landscape.

JULIET STROMBERG: A lush riparian landscape, yeah. It it we we planted many things, but we also then welcomed plants and and shrubs and herbs that that the birds brought in, mockingbirds are big berry eaters, they they brought in elderberries and things like that, and the wind blew in many plants. So, yeah, so it's this co-created oasis. It's beautiful.

But living there for for a quarter century now, you it does give one the chance to form relationships with individual trees, and not just view things as as species or as populations, but as but as individuals that are distinct and you know, like with a mesquite, for example, each the trees have a different shape, they their pods are different colors, and they taste slightly different, and you get to know and and I love to climb trees. There's that too. Some are better climbers than others, and um, so yeah, it's, um, it's been a chance to immerse myself in the plant world in a deeper way than perhaps I did as as a scientist.

LAUREN GILGER: Tell us before I let you go about one tree that you have a a really close relationship with.

JULIET STROMBERG: When we moved in, the the irrigation had been shut off for a few years. So most of the trees died. So it was a had been a citrus grove. But most things were dead, but there was one Mexican paloverde, some people call them retamas, it's Parkinsonia aculeata, that had managed to survive because the irrigation system is leaky and and when the neighbors irrigate, there's a little bit of trickle.

So anyway, this tree survived and now with irrigation, she has become huge. She's one of the largest Mexican paloverdes in the state ... and in the region and and she's just a lovely climbing tree. And she's she's sort of the matriarch. And she's she's surrounded by by all her her new babies.

And I um, partly I I'm drawn to her because when I look at her, I think about what's going on on the Salt River, which is, um, through Phoenix, there there was a federally funded restoration project, and they have target goals for certain acreages of Fremont cottonwoods and Goodding willows that they want to be there because they used to be there in the past. And they're applying herbicide to kill off trees that aren't on their target desired list.

And one of the trees they're they're applying herbicide and killing is are these Mexican paloverdes. And so it it kind of saddens me to think that this tree is being targeted and killed simply because they cross some territorial border that exists in our minds. And the planet is warming, plants are migrating, if the environment is changing, plants are changing their range, and we can't stop that process.

So we we create this mismatch between the environmental condition and the plants. The plants that are thriving today are responding to the current conditions and I guess the main approach I'm taking in the book is let's let's reverse the changes where we can.

If we can reduce global warming, if we can put water back in the rivers, if we can restore particular environmental conditions, let's do so. And I spent a lot of my academic career trying to do that. But in a lot of cases, we just can't.

Because I used to be nativist myself for a while, and I thought well, let's just restore all of the species that were just native to this region. But I sort of tossed that aside over the years because now it's like, if you can grow in these conditions and thrive and fix carbon and feed other creatures with your tissues, you're welcome. Come on in!

Let's not spend our limited time and energy trying to kill you because there's so many other more critical issues we need to focusing on.

LAUREN GILGER: We'll leave it there. Juliet Stromberg, author of the new book "The Unruly Wild," she's a plant ecologist, botanist as well. Juliet, thank you very much for coming in and telling us about this. I appreciate it.

JULIET STROMBERG: You're welcome. Thank you so much for inviting me here.

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