My gut feeling is that, in most cases, it's a relatively minor problem. Compared to some of the more invasive plants and other invasive organisms, I'd say this would have to be way down the list.

There are so many variables, it's hard to really talk about the issue as a whole. Just a few of the things that would have to be considered are:

1. Whether the native cultivar's variation from the typical species plant was significant.
2. Whether the differences would have a net negative, a net positive, or a neutral impact on the fitness of the plant for all of nature.
3. How well the offspring might pass on unusual genetics.
4. How widely and densely the cultivar was distributed.
5. If the cultivar was sterile, had few offspring, or was prolific.
6. How significantly the offspring would escape back into natural areas.

I have considered this phenomenon a number of times, mostly in a generalized way. I haven't read the source article, but I don't really see how one could possibly address the issue as a whole in any type of scientific meaningful way.

Nativars. I like it.

In a small scale planting like the Gateway Arch grounds planting all genetically identical plants is inviting devastation to the park.

In the big sense I dunno if having several hundred clones is going to make that big of a difference if you look at the number of sycamores lining the floodplains.

Now with the invasive clones things have gone too far. It is probably already too late to stop the spread of Bradford offspring w/o military intervention. And well, I suppose the military and the minimum security prison population have better things to be doing than plucking the sons of Bradfords from along the highways.

It seems to me the impact should be pretty low as long as the wild population is healthy and reproducing. This also is only an issue if the "native" nativar is planted near a native reproducing population - by that I mean if I plant clethra accuminata at my house, there are no wild types within hundreds of miles to share DNA with whereas if I planted a clone of clethra accuminata in its natural range it would have many pollen partners. The definition of native varies quite often with it sometimes meaning native to the country, region, state, or county. It does appear the article means county and probably even more site specific than that when using the term native.

Now when you get to extirpated or extinct in the wild natives, I can only see planting more of those even if they are clones as a positive. I do wonder about acer rubrum cultivars because they are so widely planted but my goodness is their wild population healthy and widespread.

Man has been monkeying around for quite a while now with food crops - veggies, fruit, and nuts. This doesn't even come close to that level of intervention ie corn etc. Native Americans would select pecan trees and distribute their progeny. IMO almost the same thing as nativars but this practice does preserve more genetic diversity.

Personally I can see two sides to this topic. My initial thoughts were that the nativar thing was logical, man again confounding natural systems. Then came back around to thinking that the interference might just be a drop in the bucket. But then, if enough drops get into the bucket...you see where that was going.

Looking at a potential positive, however, if man could genuinely improve on native plants to the benefit of bees, bugs and butterflys could that be a good thing? Like coming up with nativars that produced more nectar, nutrients and sugars for them. Of course, that's messing again with Ma Nature. Many ways to think about this.

That's why I tossed the ball to the forums to see what others think. Probably should have posted in the perennial forum as well.

hortster

Most cultivars are chosen for their aesthetic (to humans) qualities and not for their benefit to nature. Possibly, the introduction of disease-resistant varieties could be a positive, especially in cases where non-native diseases had been previously introduced. But even this line of thinking is a real "house of cards".

I'm curious if the original article mentioned any examples.

brandon7, relating to your question, an example they cite is the Irish Potato Famine. It is aimed as an example of the potential failure of cloned plants.

"An example from recent history can serve as a cautionary tale: the Irish Potato Famine.

The potatoes being grown in the country were almost entirely of a single variety, the Irish Lumper. Economic and political reasons led to the potato becoming a base food of the poor. This large dependency on a single crop and the lack of genetic diversity among the plants had catastrophic effects when a disease struck (a blight called Phytophthora infestans) killing the potato plants. [info rewritten from Wikipedia.]"

Maybe I'm looking at this the wrong way but it seems to me that a disease resistant nativar of Irish Lumper may have prevented or reduced the famine?

OK, I went to their website and poked around and I think this is pretty much of a non-issue. First of all a "nativar" isn't anything nature could not have dreamed up herself eventually. Just happenstance a human sped the process up a bit. That puts it into a whole different realm than genetically modified.

The statement making me do a double take was this " The longer we rely on nativars - clones - that are not cross pollinating in natural populations to produce their offspring, the greater the risk that we are left with only diminished selections of native plants - the nativars instead of straight species."

OK, first of all the nativars are actively participating in cross pollination, even if they cross pollinate with another like clone. We know that every time a fertilization takes place it's a crap shoot that it will produce a genetically identical offspring in the first generation. It will provide HALF of its genetic material, as will the mate. This nativar has more than one gene for each phenotypic expression and whether that particular one (or many) which are needed come together it will be more genetically diverse than its parent. Given they will also cross pollinate with the endemic population of native plants, it will result in even more diversity in the gene pool. If it bred true, like the article suggests then we woudn't need to clone it, would we?

Think of the thousands upon thousands of cultivated apple trees we plant into orchards. Have wild crabapples ceased to exist and all our pastures and wood's edges growing Pink Ladies and Winesaps? Not hardly.

We're not going to extirpate native species by using other cloned native species in large numbers . We may pollute their gene pool somewhat and come up with a bunch of little bast*rds, but unlike an ailanthus or tree of heaven, who physically just gobble up and compete for native's space, it's not the same principle at all.

I'm all for supporting more use of natives but to extrapolate consequences to this degree seems to be emotionally, rather than scientifically driven.

Calliope, I'm inclined to more or less agree with your conclusions, but I don't agree with some aspects of how you got there (or at least how you describe certain aspects).

The idea, as I understand it, of the potential for a problem hinges on the genetic pool being greatly influenced by a vast population of a single genetic pattern. In nature, mutations (especially minor ones) are very common and most of them don't make it very far. If we take that one mutation and spread it in a vast way, we could potentially significantly impact the genetic make-up of the species. Describing it as something that occurs naturally is not accurate in a big-picture way. Although the original plant may have even come strait from a naturally selected specimen (or from a simple man-made cross), the huge distribution is what's different.

Also, describing the sexually produced genetic offspring of a nativar as a "crapshoot" is not really accurate. Yes, there can be significant variation, but that variation could possibly be strongly influenced (depending on the type of trait, etc) compared to typical species crosses. The genetic makeup of an offspring of a cultivar is influenced by the genetic makeup of that particular cultivar. This is potentially very different in some way from a natural population.

This post was edited by brandon7 on Sun, Mar 2, 14 at 1:31

It is not so potentially different from a natural population. Not really. Tree genetics are more complicated than the old high school model of X and x ,Y and y. Even if you could breed identical twins, which of course in humans you can't.......their offspring would not be EXACTLY the same as the parent, since not every gene they possess is donated and which one is, is random. In this conversation, one also has to consider that any quality bred into a nativar has to also be that would tend to give it a survival advantage and that isn't necessarily true.

Please understand I do respect that humans do impact balance in nature and that even small shifts in the natural flora will impact to some degree the fauna, and have consequences. There are variables in this equation that could influence outcomes depending on our ability to literally level the ecosystems of indigenous flora and replace it with something else. I just feel that we don't have the pressure of worrying about a nativar's genes escaping into the wild and that it will ultimately purge and replace the ecosystem's gene pools. It may contribute to it, like humans are finding remnants of Neanderthal genes in their make-up........but it won't purge it.

"Even if you could breed identical twins, which of course in humans you can't.......their offspring would not be EXACTLY the same as the parent"

There's a vast middle-ground between a "crapshoot" and "exactly the same". Neither of those descriptions would be near accurate.

"...one also has to consider that any quality bred into a nativar has to also be that would tend to give it a survival advantage and that isn't necessarily true."

Ah, and there's the potential for the problem...human intervention could possibly remove the necessity for a survival advantage (or you could say that the survival advantage might become being appealing to humans rather than suitable for nature). Once well established in the population (assuming that can happen), the nativar genetics might become permanent, or at least have a very long-lasting impact.

A frequent poster to this forum, using another name in another forum, mentioned something that reminded me of another consideration. Whether or not pollinators and/or predators (seed distributors) were equally attracted to nativars could be important in determining their ability to pass on their genetics.

Good points, Brandon. I was thinking on the Irish Lumper analogy, and it struck me that of course the potato is an introduced species to Europe. Improving the genetics on it would not have resulted in a Nativar, since it was a non-native plant to begin with. I guess the direction I'm heading is about mono-culture in general, and those on a grand scale in particular. Coming to mind are issues like timbering and reforestation, where particular selections of one dominant tree might be prevalent, whether cultivar specific or not. The impact is more about monoculture on diversity than specific genetics.

Perhaps I missed it but why would this effect diversity of the plants with the exception if they are seedless or propagated?

Honestly I think the scale is minuscule compared to the time and energy that should be put forth into environmental factors that are impacting our forests. I feel like the general public is NOT utilizing what they call nativars (not crops) at a substantial rate. Perhaps serious gardeners and some municipalities.

"Perhaps I missed it but why would this effect diversity of the plants with the exception if they are seedless or propagated?"

Can you restate that question so I know for sure what you are asking?

"Honestly I think the scale is minuscule compared to the time and energy that should be put forth into environmental factors that are impacting our forests."

I think most everyone here feels the same way...at least unless/until we see information that would indicate otherwise.

"I feel like the general public is NOT utilizing what they call nativars (not crops) at a substantial rate."

I don't understand that statement. If you look around at landscapes, nativars are everywhere! If you visit a large wholesale nursery production facility, you might get a better feel for the size of the situation.

If something is invasive and I know it, I won't plant it. I grow hybrid veggies, if I am using the term correctly to mean a disease resistant variety of: Tomato, pepper etc. I plant oak hybrids, of course. I don't care for anything grafted, The few I have tried get suckers and wild sprouts, mostly apple trees, in my case.

You could only recreate the exact same plant through grafting or cutting so not sure why you wouldn't have a different plant from seed or pollination from that particular cultivar to intentionally or unintentionally get genetic variation.

On that last point, I thought about specifically stating that this is the case for WI. Most nurseries have species plants as the majority whole and therefore most landscapes have species plants. If you walk down a particular block you're more likely to find more species plants then nativars. I could say the same for much of northern IL.

whaas, let me give you an example of a scenario to illustrate people's concern:

Imagine there is a small flower that only grows in sandy soil at the edge of clearings. Every individual plant is different, with different levels of susceptibility to fungus bacteria, etc. Some gardener finds it, breeds a variety that produces a flower ten times as big (pouring so much energy into doing so it is a little weaker then the wild version). They grow a hundred millions clones from cuttings of this improved variety and sell them at Home Depot. Soon this flower is growing in a million suburban yards. Now wild flowers are getting massive amounts of pollen from this clone...and just a little pollen from other wild plants. So nearly every new plant has an identical flower and is a "half brother". This reduces genetic diversity...if the cultivated version happened to be a little more vulnerable to a particular disease then the wild version, nearly every plant in the next generation is vulnerable to that disease. If the big flowers produced by the "prettier" cultivar sap resources the plant needs to survive the winter, the wild plants are in trouble.

I believe the wild ancestors of corn are nearly extinct because they have been "swamped" by corn pollen.

Some might try to avoid this issue by planting sterile hybrids...but that creates it's own problems.
People imagine woods forever and settled land remains settled land forever, but nothing could be further from the truth. We cut down most of the US forests...but now that we can grow more food on less land, farming has been abandoned in parts of the country and we have reforestation. Where do we think the pollen and seeds that settle vacant lots and abandoned farms come from? Suburban yards. I think it's important to plant things in our yards that can provide food for pollinators and migrating birds, and can reseed vacant lots.

I wish there were more places that sold genetically diverse populations of native plants.

I get your point but that is an extreme exageration. It assumes that only one cultivar is created and produced and sold on a mass scale that would out number the wild/species plants. You also don't know what genetic variation you're going to get with the pollen. What about the genetic variation with multiple cutlviars? I think you might get more superior genetic variation with nativars at the ned of the day.

You bring another point up in a indirect way with vacant lots and abandoned farms. Those are typically getting overrun by invasives. Now that is an issue....nativars....too small of a scale to even worry about it in my unscientific opinion.

"...but that is an extreme exag(g)eration..."

It sounded like a pretty reasonably and possible real-life scenario to me.

"It assumes that only one cultivar is created and produced and sold on a mass scale..."

I can't see such a caveat, or need for one, in Edlincoln's scenario.

"You also don't know what genetic variation you're going to get with the pollen. What about the genetic variation with multiple cutlviars? I think you might get more superior genetic variation with nativars at the ned of the day."

Yes, there are many variables, and one could come up with as many permutations as desired.

Before I bought my property half (5 acres) was planted with Weyerhauser's 'Super firs'. They were selected for pulp production. They are, and have been planted, by the square mile. They are absolutely worthless as lumber and are even poor for firewood.
Will they weaken the native Douglas Firs by pollinating with them and producing soft semi-native firs? My extension service office says no. I find that hard to believe. I don't think they did the research.
Mike

I'm not a genetic expert with plants but the example appears to be an extreme exaggeration as it assumes that every plant will maintain duplicate genetic traits of the cultivar and further more be pollinated by the cultivar. Is that not the case? Will the plants take over the exact same traits?

Mike, same holds true with your Doug Fir example. Why would the native Doug Fir reproduce the exact same traits? I'd assume some would and some wouldn't.

At the end of the day trying to understand this a bit further.

It depends on the trait and the genetics involved. That's one of the variables to consider. In many cases, the trait might be quickly lost, but some other trait might be dominant. Edlincoln was showing what could possibly happen, not what was necessarily likely to happen. We are out on a theoretical limb, for the most part, but I think the intent of the thread was just to more fully examine the potential possibilities.

Wow, how did I miss this? First off, it is heartening to see good thought being applied in this thread, I agree especially with the sentiment that this is a complex issue, and one in which nearly every example, every case, would need to be evaluated on its own merits.

And that's exactly what I don't like about groups like Wild Ones approach: They would attempt to jump right over all scientific inquiry to come up with slogan material. Meanwhile-and I'm not making this up-they themselves can and frequently do make even dumber mistakes with many of their initiatives. Here I'm talking about plants at the plant community level rather than the species level. Getting all bent out of shape about a coneflower cultivar somehwere in the northern half of Wisconsin is the height of foolishness. Rather, I would question why a plant community which did not formerly exist there was being promoted as "natural", a "restoration", or somehow superior. I do "native restoration" work as a large chunk of my job and I can tell you that companies that do this work, even the top leaders in that field, typically start out right off the bat fostering the wrong plant community. Now maybe the customer specified that. In fact, that is almost surely the case in most examples, but how did we get here? From proselytizing by the owners of companies specializing in prairie plants and establishment. I could site specific examples, as I literally watched this process unfold over the last several decades.

Another problem with this one-size-fits-all approach is that it immediately makes the assumption that all plant species are equal in terms of their inherant genetic variability. They aren't. I'll offer just two examples, near and dear to my conifer heart: Red pine-Pinus resinosa-is among the least variable species known to man. Replicants from Maine would have nearly identical characteristics to those from my own state. Meanwhile, Norway spruce, from the same plant family-Pinaceae-is wildly variable, even from within the same geographic area.

Then to top it off, WO uses potato as its prime example. I see others have already commented on the unsuitability of that plant to elucidate anything from this question. Potato?

It should be obvious I've had more dealings with these folks than I care to. It's too bad really-we share nearly everything: Love of nature, concern for future genetic diversity, etc. but in my opinion, these folks get it wrong more often than right. In any case, the answer is quite honestly that it depends......on just those factors we've listed within this thread. Are extant populations of the species in question living alongside plantings of these nativars? What trait within any given nativar was selected for? Are thriving and widespread populations of the species living in abundance and across wide geographic area? We could go on and on.

+oM

My first thought is that it sounds a bit esoteric and "Gaiaist" Coining the term "Nativar" is unnecessary and comes of sounding a bit too jargonistic and a tad arrogant.

But, laying aside my personal qualms about their presentation, I would say that the rest is a bit overdone and pretty much the same "Evil Humans" that comes in greater or lesser quantities from too many environmental groups.

If a nativar is a cultivar of a native plant, that would mean that all the Eurasian cereal crops are nativars along with the majority of our decorative plantings even in North America. Excepting, of course the purely species plants. These nativars have been growing in Eurasia from at least 10,000 B.C. Has there been any diminution of the gene pool in Eurasia because of these nativars? Perhaps a study by a major University is needed to answer the question, but I would dare say the answer is no. It is possible to go to the parts of Eurasia where the cereal crops were developed and find the ancestors of those plants growing quite well. When fields go fallow, these ancestral wild grasses will very happily recolonize the empty fields. Japan has been cultivating their thousands of varieties of maple for hundreds of years. Has this harmed the gene pool of the native Japanese Maples? Has the Chinese cultivation of the Tree Peony damaged the population of the wild stock? Are the forests of Europe or Asia being overrun with savage hoards of mutant hostas? I rather think not.

At this point, I think a diversion to the potato famine is in order, only because it has been brought up in previous messages. In this instance, the potato would not be a nativar as it is native to the Andes of South America not Ireland. The potato blight was not caused because of monoculture. Nor was the resulting Irish Famine. The blight was caused by the fungus Phytophthora infestans which actually seems to have originated in America. It devastated potato crops through out Europe. The difference was that in the 1840's Ireland was the poorest place in Europe. Rather akin to Haiti now. Because of racial, religious, social, political and economic factors, the only thing the poor in Ireland had to eat was the potato. Other European countries had something else their poor could fall back on, not so in Ireland. It would like having a near total rice crop failure in China for five or six years running and having the government telling the poor they could not eat the wheat or other crops the country was producing in abundance, and the government refuse to bring in other foods because it would lower the market price of local goods. For more on the subject I would suggest a book titled "The Graves are Walking" by John Kelly.

Having gotten that out of my system, I'll move to the Americas.

In America, we have relatively few nativars. There has not been thousands of years of cultivation and gardening here as there has been in Eurasia. The most common nativar would be corn. By 1492 corn was being grown any place in North America that could possibly have a corn field. Even at that date, there were multiple varieties suited to many different growing conditions. Beans and squash would also be grown in the corn fields. In central America you could add chilies to that. None of them would have been a species, all would have been varieties or nativars. Cultivation of those plants has been going on here for about five thousand years. It's a little late to start worrying about these nativars. By the way, there are still ancestors of modern corn growing wild in the Maya areas of Mexico. They are called teosinte.

The worry that nativars will swamp the gene pool of their uncultivated relatives is unwarranted. We need to remember that plants are, even within species remarkably variable. They will frequently produce sports and varieties. Some of these sports will go on to produce a viable subspecies. Most would consider the fastigiate form of the English Oak, Quercus robur, to be a variety. But in my experience, they will come true to form from seed about 80 - 90 % of the time. Perhaps it should be considered as not a variety but a sub species.

Few of the different varieties of ornamental tree or shrub have been produced intentionally. Most started out as a sport and were then propagated. All those different kinds of Beech and Blue Spruce started like that. Many will also revert back to the species. I think we have all seen a dwarf Alberta Spruce with a branch that has returned to the original species form.

There should be very little worry about the effect that nativars will have on wild populations because of limited genetic diversity in nativars. By selecting only a few characteristics in a wild plant and breading cultivars from that will usually result in a plant that has the form or color etc. that is being selected for, but it is also likely to produce a plant that is weaker than it's wild ancestors. If the nativar should pollinate a wild relative, the resultant offspring will have a mix of the more robust wild parent and the weaker nativar. Those that take after the nativar more than the species will probably not survive long in the wild, the line will die out and the species will survive none the worse for the wear. Natural competition will select for the characteristics that will best compete in that environment. By and large, the nativar will inevitably loose out. Most nativars need human intervention. Corn can't crow without it. Nativars, cultivars, whatever you want to call them are genetically unstable. Left to their own devices, those that can survive without humans, after just a few generations will revert to the original species form. It works in the plant world and in the animal world. Nativars are just not a threat to biodiversity.

I am well aware of the pathogen infecting the potato, and reiterate that in essence they depended on clonal monoculture to feed their poor. Had their planting consisted of more than one crop, and essentially one with little genetic diversity, the results would not have been the same.

Here is a link that might be useful: irish famine

Just to play "devil's advocate", I find as many holes in drpraetorius's post (especially, many assumptions) as I do in what has been presented as Wild Ones position (I have not read the source article, so can't say for sure what Wild Ones actual position is).

I wondered some time ago about this issue, but in terms of forest trees. Back before EAB appeared, various ash species were workhorses of the landscape. Take F. pennsylvanica for instance-the green ash occurs naturally across a wide range. So we bring in genetics of "patmore" or what have you, in close proximity to native and naturally existing stands of green ash.....might we not be accidentally introducing less suitable genes into the picture by doing so? Or, to be completely neutral, maybe some useful genetics as well, depending on who is making that determination!

I pose this because, just as I railed that many forbs are not really what the landscape would have held in the past (In previously forested areas) as dominant vegetation, the use of "native" but non-local tree types could have the ability to do far more damage,

Still, I am not sure if this has ever caused one bit of trouble. But it is, to me, far more worrisome than is the introduction of nativars of species which, were the world to suddenly revert back to its own wits, would have no chance of taking over the landscape anyway.

Then too, we're flat-out losing whole genera these days. Look at ash...they're quite possibly going to be eliminated from a huge swath of their former territory. Or eastern hemlock out east (Not affected around here yet, gladly): Might it not actually be desirable, if not necessary, that some non-native species naturalize and take over the now empty niche previously occupied by hemlock?

Finally, no matter the reality of this situation, I believe it pales in comparison to the overwhelming effects of land use changes that are eliminating native (And mixed) plant communities across the land as we rush to build that new gas station, Hardees, McDonalds, a new ring of malls around the old ring of malls, etc. Just the outright conversion of land through development is the issue, again, in my opinion.

There's so many parts of this debate that I find myself somewhat at odds with the general consensus. Go on a rampage against Dame's rocket? What for, so the burdock and garlic mustard have more room to grow? Spend dollars and resources to stop phragmites? Why, so narrow-leaf cattail can expand its range? And on and on....I don't get the feeling that some of the native landscape proponents are seeing the big picture. Oh, and I get to do a presentation to a bunch of these folks on Tues!

+oM

I tend to agree with you. Good luck on the presentation, because you are likely going into an audience with preconceived opinions and some militantly so.

If I may be allowed the space to continue tirade, even if the it full of holes; I would first say that the article in question is simply bad science with more philosophy than actual science. Please take the time to read it.

http://www.wildones.org/wp-content/uploads/2013/12/Nativars-Statement-with-reference.pdf

There is not one specific, verified, example of any damage done to a native population by the use of "nativars". As I said in my previous posting, there are no savage hoards of nativar Hostas rampaging through the forests of Eurasia. The same can be said for Franken-Flower coneflowers in the Midwest. It just isn't happening.

It is very important to have a modicum of understanding of how genetics and mutation works. Most mutations are both recessive and undesirable. A chance mutation appearing in a native population will only continue and get into the general gene pool if it is either beneficial or benign. If it is beneficial it will work its way through the population by giving those that have it a competitive advantage. If it is benign, it will continue to show up but not very often and will not make any difference to the viability of the species. Those mutations that are deleterious produce individuals that will either not live at all or not be able to compete in nature and thus not reproduce. In our case, a weakened plant.

Nature selects for strong plants that are able to compete and reproduce in their own niches. Humans do not. Most of the modifications humans make to plant and animals are done for our own purposes and tastes. Because we are selecting mostly mutations, the resultant organisms are less likely to be able to survive in the natural world. Big flowers with floppy stems and cows with huge udders are the same thing. Neither one will be an advantage in nature.

So, what would happen if we planted on species of coneflower (since that seems to be the favored plant in the article) and surround it with acres of a single nativar of coneflower. What will happen? Over time, and I don't know how long, ALL of the coneflowers in that area would be the native species. Why? Not all of the nativars would be able to survive to reproduce. Those nativars that did survive would be reproducing by seed. Even though the nativar looks different from the species, it still has much more in common genetically with the species than differences. That includes the basic genetics that make it a coneflower. Each seed produced by the nativars would still have a great deal of genetic diversity. Those that are closer to the single species coneflower would have even more diversity because of crosspollination. The rules of natural selection would still be in effect. Only those seeds that are viable would germinate and only those seedlings that are strong would reproduce. Since the proven form is the species form, nature would select for that form.

There is also a reason from physics for this. It is called entropy. Going from an organized state to a disorganized state. From complex to simple. A cultivar is a more complex form of the organism, a less stable form. It takes more energy to maintain the cultivar form. It takes less energy to survive in the species form.

This drive to return to the species form is seen in both plants and animals. What happens to Phlox that are allowed to go to seed? Do they retain the fancy forms and colors? No, they revert to the species form. Freesia? Same thing. How many high quality apples will you get by planting seeds from your favorite apple? Probably none. They all want to revert to the species form. It may take a few generations but anything that is not a competitive advantage will eventually be jettisoned.

In fish, those fancy guppies will go back to their original form if allowed to breed at will. Betas will do the same. Have you ever seen what happens to populations of goldfish that are allowed to breed indiscriminately? They become plane old ugly carp. One of our oldest breeding experiments has been the dog. What would happen if we let our dogs breed at will. In Australia, they became Dingos. You can see similar populations in poorer countries with big cities and open garbage dumps. The dogs tend to be of medium size, yellow with pointed ears held up and curled tails. In the southern U.S. we see feral pigs in the process of reverting. It is just a given that varieties are inherently unstable.

Unless there is some empirical, verifiable, replicable evidence of any degradation of the gene pool, the nativar problem is philosophical, not scientific.

My opinion is...

the original article referred to is a pretentious bunch of crap that has more interest in preaching to the choir using fallacious arguments, pseudoscience, and crusading rhetoric than actually addressing a real issue.

To use the Irish potato famine as an exemplar of their case is an example of making their argument at the expense of good, actual arguments.

Let's continue to pick on green ash. Cultivars are selected for reasons that people deem to be worthy of being perpetuated. Faster growth, seedless, foliage more resistant to tatter, fall color, among others. These are all traits that are part of the natural variation within a species, just selected for specific reasons. If you were to grow a crop of seedling grown ash for sale, you have a cull rate of 30%. Even if you select the seed from known parents, maintained in isolation, you still have a cull rate of 30%.

Or perhaps we should use an example that could prove that such contamination of genetics could exist: White Spruce. In one place in this country, a 400 square mile region of south Dakota, Black Hills Spruce naturally grows from seed, dropped from parents themselves grown from seed, in a cycle that goes back eons. Who is going to argue that the resulting subspecies is inferior, of lesser inherent value, or less desirable than the species?

Species such as A. palmatum and Chamaecyparis obtusa illustrate just how much diversity potentially exists within a species. And if you collect the seed of the dwarfest clone of Cham. obt. grac. nana, you will still have only a small percentage of the resulting progeny looking even a little like the parent.

We do have plants where human breeding resulted in a number of less desirable traits; roses are an example that comes quickly to mind. And yet, should you desire to enable a breeding program, you can find prime genetic parent material readily available for even a paltry budget that a hobbyist could acquire with only a little inconvenience.

So that's for the essay part of this. I've been working in nurseries for over twenty years, and I can tell you this: It is wrong to say that the number of people who do not understand what a cultivar is or is not is shocking. It's shocking to know how many people don't care to know what a cultivar is or is not. Fundamental things about plant genetics are as much a part of an average person's thought process as understanding thermal and hydraulic dynamics on Io.

And yet, we live in a time when people care about the natural world. That's the important part, they care. You have to say that with feeling. And if the important thing is that you (capitalized) care (italicized), it's not at all important that you get the facts right: It's important that I know you (capitalized) care (italicized). And if you don't know that I know you (capitalized) care (italicized), then that's not enough.

So people care. Maybe once upon a time, if you cared about a subject, it was enough to educate yourself upon the subject and arrive at a variety of conclusions based on sound reasoning, collection of information, and reviewing other's opinions, who had themselves gone through a similar process, and then had the gumption to write about it.

How naïve. How plebian. How...twentieth century. You remember that time, when people used pencils and paper, had only one phone that was mounted to the wall, had lights that actually turned on when you flipped the switch, and (gasp!) weren't required to have health insurance?

You have to define the problem in your terms and mold those innocent minds into becoming acolytes of your cause. Rally to Arms! The enemy is invading! And the enemy is Hardees! The apocalypse is upon us, and the fourth horseman is a thickburger!

I mean, the enemy is a coneflower! We will be able to make the world safe, if only we can stop the pernicious assault of the invading coneflowers. We must draw a line in the sand, and we must stop the coneflower! But only those coneflowers we deem to be bad. Those, over there. These, over here, are good, are wholesome, and will reduce the spread of radioactive nuclear waste. Those, over there, will increase taxes, lower sperm motility, and are a primary cause of obesity. These, and only these, feed butterflies, shelter rabbits, and solve the debt crisis. And they are dishwasher safe!

See how it's done?

and the fourth horseman is a thickburger!

Now that was funny!

Good discussion...very interesting read to see everyone's opinions.

My scenario is one that I'm pretty sure has happened. The only real questions are how typical this scenario is, and whether the harm caused by this possibility is greater or worse then that caused by invasives or sterile hybrids. (People forget in these debates we are choosing between options, and choosing "none of the above" often isn't an option.)

I've heard of this happening to a few plants, although I can't recall which ones. As I've said, I know something similar happened to the wild ancestor or corn...although that was less about disease resistance then the fact domesticated corn has trouble reproducing without assistance. There are lots of times when there is (at first) only one cultivar. The sum total of the genetic diversity of the next generation is the genetic diversity of the parents...if all the next generation have the same father, that reduces the range of genes in the next generation. You don't have to assume only one cultivar...if you have 3 or 4 or 6 cultivars, that still means only 3 or 4 or 6 fathers for most of the next generation.

The jury is still out on just what was the ancestor of cultivated corn, was just reading a treatise on it several days ago. I suspect corn as we know it didn't just have ONE ancestor, anyway. Whether any one of them went extinct or not, may or may not have had anything to do with corn planting and loss of genetic diversity. There is reason to be concerned with loss of genetic lines, it's nothing to be made light of, however. Having been in the nursery trade for many years, I can say that one cultivar of ANYTHING seldom stays popular for very long, least of all long enough to dominate another to the point of being extirpated or driven to extinction. This decade's purple-leaf choice with pink flowers will eventually fall from grace for next decade's dwarf variegated cultivar with white flowers. I can also say that basically if there are beneficial insects or fauna who depend on one cultivar of plum or maple, they most likely will also accept another. Can't think of any right off the bat who are so choosy that one can't be substituted for the next.

nativars are the result of artificial selections made by humans from the natural variation found in a species

I like the term nativar to describe a cultivated variety of a native plant, but why does that make the selection "artificial"? If it was a natural variation it was created by Nature in the first place.

I don't see a big problem with using nativars, or cultivars of non-native species that are not invasive, and enjoy their unique traits. But they are used mostly in the gardens and for the most part stay in the gardens. The vast majority of woody plants which compose the "backbone" of the vegetation growing on my lot are genetically unique seed grown individuals.

I do see a lot of problems with the incessant human development of native habitats; the spread of non-native invasive plants; and abysmal land management by many residential property owners - and think these are far bigger threats to wild populations of native plants than nativars.