Years ago, my neighbor threw out his unwanted heavenly bamboo (Nandina domestica) into woods on my property. Without any help from me, this has now been a sustained bush back there on its own, two of them in fact. Would this be considered cultivated, or could it be a research grade observation considered naturalized?
I think the first plant is considered planted and any after it are naturalized
Agreed. The second plant germinated without human assistance and presumably is surviving without assistance.
A plant that germinates in a garden but only survives a hot, dry local climate because the garden has sprinklers, OTOH, would not be naturalized.
Если выброшенное растение полный год, а лучше два, выживает без ухода со стороны человека - его уже можно считать одичавшим. А если оно ещё начало самостоятельно размножаться - то несомненно одичавшее.
If the discarded plant survives for a full year, and preferably two, without human care, it can already be considered feral. And if it still began to reproduce on its own, then it certainly went wild.
I agree with you in principle.
iNat rules say that what matters is whether the specific plant was put there by a human, even if 200 years ago and without any further help.
We differentiate between a plant persisting from cultivation (or from being discarded, in this case), and plants that have managed to complete a life-cycle on their own and reproduce (i.e. naturalised).
If the first plant has reproduced and given rise to the second, then the first plant is not wild, but the second is.
this one is edge case. We definitely don’t track dandelions that pop up on their own in lawns as captive even if it’s an irrigated lawn where there would never be one.
It’s likely that it spread by vegetative means rather than seeding and a new plant germinating. Personally I don’t think that matters, I think I would probably consider the second plant wild. Arguably the first plant could be considered wild too since it was dumped rather than planted.
I could see there is an argument that the rules might mean neither is wild, but if so what about something like Japanese Knotweed? In the UK this is a single female clone and every plant has spread by vegetative means in some cases with the help of humans. I think most people would consider it to be wild.
There must be lots of plants which haven’t been planted by humans but wouldn’t be growing where they are if it wasn’t for human intervention. Plants growing on land reclaimed from the sea, plants growing in human created ponds, lakes or wetlands, weeds growing in lawns, plants in hay meadows, salt tolerant plants growing alongside roads away from the sea. In some of those cases it was a one off intervention (e.g. a lake in an old gravel pit) but many habitats only exist due to continued human intervention. In the UK a large percentage of the land area has some level of continual human intervention, including many of the parts that would be considered wilder.
I would be very wary of that heavenly bamboo - it can become invasive. By runners and berries.
This is my constant question about prickly pear cacti - I think all the ones I ever see around here were once thrown out of yards in the 1930s-1980s, but they certainly seem to be growing etc without intervention. By iNat rules, they appear to be cultivated, but they seem naturalized in my view.
Perhaps we’re trying to cover too many situations with too few terms. Perhaps rather than insist that people learn our convoluted definitions we should come up with a set of terms that most people using the site will understand more easily, and often without having to read the definition. In this post I’m going to explore this a bit. As you read, don’t quibble over whether my terms fit the definitions I am giving. Consider whether the definition I am giving describes a unique situation that we need a label for. If you agree with my choice of word to pair with that definition, you and I have a label that works for us. If everyone agrees with us, we have the perfect label. The greater the number of people who disagree with us, the greater the likelihood that our label isn’t the right one for iNaturalist. We would need to find that term.
So, here I go.
Taking the terminology strictly at face value, a plant is not cultivated if no one cares for it, so the discarded plant that rooted on its own would be wild. It was started by a careless human instead of a careless bird, but it definitely was not planted intentionally and cared for at any point beyond its introduction to your garden.
In North America, zebra mussels supposedly started as a group of organisms flushed from the bilge of a freighter in the Great Lakes. While in the bilge, they could be considered captive, but once released they certainly were not. Why should a cultivated plant uprooted and released by a human be any different? It can’t move elsewhere on its own, but it could either die or take root. Its further survival is not due to the intentional action of humans.
One term covers both situations: “Introduced.” If an organism got there by human intervention, it is introduced. We can then use the note associated with the observation, tags, or both to give further detail: “established from brush discarded on my land by my neighbor. First of this species seen on my land.” I’m not cultivating it, so it’s wild. It got “here”—whether “here” is this continent, this nation, this city, this watershed, or some other geographically significant region—by means of human action, so it’s introduced.
For introduced organisms, we should add further tags. For example, we need to know whether it’s accidental or naturalized or invasive:
- If you were to call it accidental, I would understand that to mean that it does not reproduce in that area. I might occasionally find other individuals in the area, but no established populations. If Nandina domestica couldn’t reproduce in your area, that second shrub wouldn’t be there and the rooted discard of your neighbor could be considered accidental. (Maybe there’s a better term.)
- When an organism is described as naturalized, I understand that to mean that it does reproduce in that area, but not to the detriment of other species of its type or entire habitats. If this description fit Nandina, you would find it here and there in your area, reproducing on its own, but not choking out other plants.
- By contrast, an invasive species is dominating the habitat. In my area, this definitely describes Nandina. It can and often does establish itself so thickly that many other species are affected. Other plants are choked out. More open spaces become thickets, so predators have a harder time finding their prey. You can think of more examples.
If those definitions are three reasonable categories that, taken together, cover all possible cases for “not native to this area,” then we need to find the label that works best for the most people. If it doesn’t cover all possible cases, then we need a definition for each of the other cases—and we will need to find a term for each of those, too.
Notice the direction we are going: not defining terms so much as, to strain English grammar, terming definitions.
In distinguishing naturalized from invasive, I implied a fourth situation for which I have no term: Harming at least one native species not of its type. For example, it’s an understory plant but it isn’t necessarily affecting other understory plants. Instead, it has affected a native species in a more subtle or indirect way. This is an overarching category; in other words, it’s independent of whether the organism is cultivated, accidental, naturalized, or invasive: Staying with Nandina domestica as our example, if any of these instances arise, then it would belong in this fourth category:
- Instance 1: It provides habitat from which a predator can ambush prey, and is so effective in doing so that the population of a prey species starts to decline. Even an accidental introduced organism could fit this criterion—especially if introduced into the very small range of that prey species.
- Instance 2: Its fruit is poisonous to one or more native species. I understand that this actually is the case with Nandina domestica, as the bird’s metabolism produces a toxic substance from a compound in the berry. Nandina domestica might have to be invasive to be a problem from this perspective. In other words, it might be the case that a naturalized population would affect individual birds but wouldn’t significantly reduce the overall population of any one species of bird.
- Instance 3: By being in the ecosystem, it adversely affects the ability of some other species to survive. Imagine a case in which the berries of Nandina domestica are not toxic to any species under any conditions. In fact, let’s imagine that they are a superfood for birds. They’re tasty and so nutritious that the birds neither want nor need to eat anything else. In that sense, a naturalized population would be beneficial to many species of bird. Even a cultivated population at the level of a row of Nandina in the landscape of one house in each block might provide the full benefit. The birds wouldn’t have to rely on the weather to produce a steady supply of food. But what about the native fruits the birds used to eat? What if one or more of those species stops reproducing because its seed won’t sprout unless it first passes through the gut of a bird? It doesn’t matter how many of the introduced plants per hectare it takes for the native birds to stop eating that fruit. Regardless of whether it’s cultivated, accidental, naturalized, or invasive, the introduced plant is suppressing the proliferation of one or more native plants.
So take this as food for thought. How can we better define the categories we need? And then how can we label those categories so as many people as possible will use those labels correctly?
And perhaps there more categories to define. Our work has only begun.
New Zealand is said to be the “world leader” in plant naturalisations. Its entire flora, as predicted by Darwin on his second visit to NZ I beieve, is severely reduced and threatened by ongoing plant invasions, with the number of naturalized species (currently about 2500) increasing daily.
So it is a matter of great concern to land managers and ecologists in NZ.
Peter de Lange (pjd1 on iNaturalist.NZ) has been evaluating, cataloguing and defining such naturalizations and invasions. In reply to a query of mine last year, where I was wondering how to describe a naturalized plant occurrence, Peter said he had developed a scale of, I think, about 8 terms describing method and stage of naturalization or invasion, in various paths eg vegetative spread, by seed, under parent plant, 2nd generation spread etc.
So a lot of work has been done, and anyone interested in the issue might do well to see if they can use the work he has done. From what I remember of Peter’s comments, the scale, or categories, were not specific to any geographic area, they just made one look at how the plant had got to where it was, and make an assessment of its invasiveness on that site to date…thus facilitating (I assume) ongoing assessment of the invasion potential of that species in that area and those conditions, etc.
NB and @jfox16 that was a great observation by the way, of the kind highly valued by researchers here as they try to track and anticipate plant invasions. It is good practice, here in NZ at least, to report both plants publicly, ie make the iNat observations eligible for ID, and to describe their situation and likely origin, as another poster suggested.
South Africa has this
Perhaps other countries have similar projects on iNat?
Interesting scanning the speciesin that project Diana! We share a few of them, but interestingly many of the Australian plants are unfamiliar to me. Black wattle, unfortunately, is not.
We have the project “Pest plants in NZ” https://inaturalist.nz/projects/pest-plants-weeds-of-nz
but it is not very active recently it seems. I created “Invasive weeds of Kaipatiki Creek” for one local area.
I need to update the latter project too, as a lot of species have probably been found more recently.
Time to add even more confusion and frustration to the pot—Bamboo often spreads with runners, which means that if it’s close enough, the new bush may well be a clone connected to the original. …And that makes this whole question of planted vs naturalized even trickier since it brings up the question of whether naturalized does or should extend to connected clones as opposed to just separate individuals… Is there a standard way this is handled in botany?
And for yet more annoyance… heavenly bamboo is neither a bamboo nor heavenly
I think it’s one of those names that people hear and the “sounds like” version takes on. Nandina is one of those plants that if you are going to fly-tip it, better to put it amongst something even more invasive and competitive in order to stop it establishing, such as bamboo… Hence, when dumping, you must “heave in de bamboo, as far as you can”
[Intended as humour, author does not endorse fly-tipping, please dispose of refuse in council approved landfills so that it can be undercut by rivers and washed out to sea]
It’s an edge case but I’d still call this “cultivated” in the iNat sense that it’s not wild. A person planted the Nandina and then another person moved it to its current location, so it’s not wild.
Some time back I made an observation field on iNat called “sourced from garden waste” to keep track of such observations. We’ve been using it in NZ, since dumped garden waste is an important way that some of our weeds are moved about.
@dianastuder That’s an interesting project. I wasn’t aware of that. Here in New Zealand, we’ve started work this year on automating the detection of new plant naturalisations in NZ’s districts, using the iNat NZ plant observations and our lists of what plants we already know are naturalised in districts.
There have been two steps slowing us down. The first has been pulling together NZ’s various plant naturalisation lists in various states of completeness, age, and geographic scope, filled with assorted typos and out-of-date taxonomy. (I’d be interested to know if South Africa is more advanced in this.)
The second has been sorting out the many iNat NZ plant observations that users haven’t marked as cultivated but clearly were cultivated. We need to get better as a community (in NZ at least) at keeping the wild separate from the cultivated.
I appreciate @jfox16 asking for clarification here. It is important for invasive plant research and management that we all keep cultivated and wild plants separate on iNat.