The Nativar Dilemma

Stamford CT, August 25, 2011

To continue last month’s discussion on determining what’s native, etc., I’ve saved the most frustrating part of this discussion for last: nativars. “Nativar” is handy term becoming popular to describe “near natives” of various sorts. The term covers any plant that is somewhat closely related to a local native plant but not quite it – usually garden cultivators or hybrids of native plants, including non-local genotypes of native species.

Here’s the issue: why not just buy that pretty wildflower being sold at your local nursery? That species is native to your area; however, chances are that the local nursery’s stock does not come from your area, but so what? It’s good to support the local nursery’s effort to offer sort-of-natives, right? Meanwhile, it can be much more time consuming and expensive to acquire local genotype natives from a specialty grower, and their plant lists can be a bit limited. Further, just how local are the specialty nurseries anyway?

Accordingly, the suggestion is often made that the next best thing is a nativar. But is it?

Picture: wasp (omnivore) at the Bartlett Arboretum in Stamford CT enjoying the pollen of a local-genotype meadow rue

To review the basics: The local herbivores, including most of the native insects which feed the birds, fish, and toads, etc., often can not recognize foreign plants as food. At best, foreign ornamental plants are taking up space that could support useful plants which would feed the native wildlife and/or you. At worst, these plants become invasive, crowding out the beneficial native plants.

In a place like Fairfield County, where I live, there is so little uncultivated space left and so much of that is overrun by white-tailed deer, that we need to make every inch of yard count.

The idea behind nativars is that they may be an acceptable substitute for the local insects and other herbivores that are the essential link in the food chain from plants to omnivores and carnivores. Sometimes the nativar works out, at least for some critters.

However, sometimes it doesn’t. For example, the Connecticut Butterfly Association observed that our adult monarchs wouldn’t touch the pollen of Michigan-grown echinacea – my guess is that a slight difference in chemical composition in the Michigan-genotype prevents our monarchs from recognizing the plant’s pollen as food. Likewise, I have noticed our local pollinators shunning garden cultivars of our native snakeroot.

Picture: goldfinch lunching on echinacea in a parking lot planting at Stamford's Cove Island. Local genotype plant? Probably not; probably a “nativar”.

OK, so not every insect will eat the nativar, what harm? Perhaps none; perhaps a lot. We have all seen how related species that bloom at the same time can interbred. For example, the London plane tree is said to be a spontaneous cross of the American and Asian sycamores left to their own devices in England’s Kew Gardens.

This can also happen with local genotypes and nativars. The biggest danger is that the nativar may interbreed with local genotype, destroying and replacing the local genotype. The result might be no ecological harm at all. On the other hand, the interbreeding might turn a local genotype into a plant that the local fauna can not recognize as food, or, worse yet, into an invasive. What can also happen is that the non-local plant is not as hardy as the local stock and the interbreeding weakens the local stock to the point of extinction. So the potential harm is that we lose the local genotype, with a resulting impact on the overall ecology.

When I first heard this, I was shocked and depressed – so much work trying to educate people to plant native and now, come to find out, if the plants they were putting in aren’t the real McCoy, maybe they were doing more harm than good! How are we going to get the average gardener to understand local genotype? I didn’t want to believe it but a botanist friend of mine, the amazing E. C. Morgan, started digging up studies. See for example, Problems Associated With The Introduction of Non-Native Genotypes On NRS Reserves, Committee to evaluate introduction of exotic genotypes into UC Reserves by John Endler, Chair Susan Mazer, Mike Williams, Cristina Sandoval, Wayne Ferren.

Picture: young eastern cottontail rabbit at the Scalzi Riverwalk Nature Preserve prefers local-genotype hog peanut leaves.

Which nativars will fully function, and safely function, in the local environment? The answer would require would require years of study for EACH cultivar. This is obviously not practical so, of course, the best bet is to go for local genotypes.

But what to do when acquiring the local genotype isn’t practical? Right now, as far as I can see, it’s a crap shoot. This is an area that needs more study and discussion particularly at the lay level. After all, we lay people are doing most of the planting and most of the educating of the general public, so are most in need of whatever guidance the botany community can provide.

I, frankly, don’t know the best answer, if there is one. Today, I would not think twice about planting nursery-stock blueberries in the average urban garden – great fall color, delicious fruit for the birds, and, perhaps, a local insect host. Further, any blueberry is so much better (I hope) than the winged euonymus (firebush) which is often planted in my area for similar fall color and which has become our dominant invasive understory shrub.

When it comes to the suburbs, however, much of the suburbs in my area is now represented by giant houses on one-acre or larger plots smack in the middle of the now-fragmented forest, often abutting a wetland. In these suburban areas, whatever is planted is being injected directly into what’s left of the local ecology. In these areas, I would be very careful, for example, of getting a non-local genotype blueberry anywhere near our treasured local subspecies, the swamp highbush blueberry.

At this time, the best I can say is don’t let the ambiguity and lack of definite “rights and wrongs” stop you; we need to keep trying until we get it right. Each local native plant and animal that we save matters. Just be aware of the issue and don’t assume that nativars are safe and useful – get the local genotype if you can. Over time, hopefully, the plants nurseries that offer local genotypes will expand to the point where this is less of an issue.

Additional reading: Vincent Vizachero’s Native Cultivars – Good, Bad, and Ugly

All readers with thoughts on this critical subject: please chime in. Please leave a comment and join the discussion. We can’t wait to hear from you.

© 2011 – 2012, Sue Sweeney. All rights reserved. This article is the property of Native Plants and Wildlife Gardens. If you are reading this at another site, please report that to us

Related Posts Plugin for WordPress, Blogger...
    About Sue Sweeney

    Master Gardner Sue Sweeney, a life-long naturalist and gardener, specializes in non-chemical, minimally-disturbing conservation area restoration.  She is a freelance nature photographer, and author of numerous articles on urban flora and fauna, chemical-free gardening, and similar subjects.  A passionate environmentalist, Sue lives in a downtown high-rise, and does not own a car.  Her indoor and balcony container garden has shrunk over the years, from a high point of around 500 plants, as her responsibility for Stamford-area conservation work has grown.  Currently, she is Volunteer Head Steward of the Scalzi Riverwalk Nature Preserve near the heart of downtown Stamford CT and teaches conservation restoration to Master Gardeners Interns and other interested parties.  Email Sue for more information.

    Comments

    1. Loret says:

      Thanks Sue for giving excellent food for thought. I raised the question on a different post this week. I live surrounded by Conservation land and since I have learned about provenance I no longer will buy anything touted as native at the big box stores because little is known of the origins. I do shop at a local native plant nursery involved in restoration since I know the standards they follow in propagation are to keep the “real” natives from becoming victim to designer plants.
      Loret recently posted..My threatened species….REALLY?

      Reply
      • Vincent Vizachero says:

        Loret, I just now replied to your comment on my post! Sorry it took so long. I’ll paste it here, too, just for continuity.

        ============

        In the vast majority of cases, using a native plant of non-local provenance in a landscape context will have no discernible effect on the gene pool of “wild” plants. The two groups may cross-pollinate if they are very close to each other, but the dynamics of population genetics suggest that it is not a big concern. Of course we would always prefer a local source, and a genetically diverse local source at that, but planting a yard full of non-local natives will not “much up” the genetics of local populations to any worrisome degree

        If you are working on a restoration-scale project (i.e. seeding many acres at once), then a concern might be justified but that is a problem most readers of this blog probably aren’t grappling with.
        Vincent Vizachero recently posted..Want to Avoid Nativars? Look Here.

        Reply
        • Sue Sweeney says:

          Vince – How do you know this? Can you point me to any studies? Do you feel the study that I cited was in error?

          Reply
          • Vincent Vizachero says:

            Sue, I don’t necessarily disagree with the arguments that Endler was making in the guidelines you cited.

            His arguments, however, primarily concern the kind of large-scale restoration-type efforts I mentioned above (as you would expect given that he is talking about the UC Natural Reserve System). His guidelines are also primarily focused on the ability to use the reserves in biological study and experiments, which could easily be “contaminated” even when the actual health or integrity of the plant populations was not impacted at all. So even if he is completely right, it does not necessarily follow that homeowners planting cultivars is a bad thing for anyone except John Endler. In other words, it MIGHT be bad but it might NOT be bad.

            Which leads to my final thought about those UC Natural Reserve System guidelines: they do not explicitly reference any studies which demonstrate the observation of any “Problems Associated With The Introduction of Non-Native Genotypes On NRS Reserves”. Rather, the guidelines present a rather lengthy and detailed account of hypothetical and/or potential problems. I’m not saying the outlined concerns are not justified, but as far as I can tell Endler et al. have not actually proved that non-native genotypes have yet caused any actual problems.

            I’ll admit that I’ve spent a whole lot more time thinking about human population genetics than plant population genetics, so I certainly wouldn’t want to say that using a native plant of non-local origin in residential landscapes is a harmless pursuit. But personally, I’m much more worried about the performance of the non-local plants in the residential landscape than I am about contaminating local wild gene pools. I’m not aware of any study that demonstrates this kind of genetic contamination, even though it could very possibly exist.
            Vincent Vizachero recently posted..Want to Avoid Nativars? Look Here.

            Reply
            • Sue Sweeney says:

              Vince– love your post. I wish we had equally good resources in CT. Most of our resources for local plants are good only to the regional or state level – not bad but not truly local – and most are located many miles away and are accessible only by car. (CT readers, do try http://www.earthtonesnatives.com)

              There are studies about specific plants being overtaken by non-local genotypes, the studies are beyond my technical level, but I will try to get some cites.

              Moreover, every day I see white mulberry with a tinge of our red mulberry that it replaced; I see American sycamore with a tinge of the Asian cousin whose genes were brought into our community via the London plane tree. I’m sure you see the same thing and can name several other cases where our native stock has been corrupted by a foreign cousin that blooms are the same time.

              If local and non-local genotypes of the same species placed near each other interbreed (and why won’t they?), the changes probably won’t be visible to human eye in the way interbreeding of related species is. All we’d notice is different insect behavior (such as no holes in the leaves), may be an absence of the plant where we used to see it, or, worse yet, may be much more of the plant than we used to see. Unfortunately, we’d have no way of assigning a cause to the changes we’d be observing, and if we weren’t all that familiar with the plant we might not even notice the changes.

              my last note: I don’t think that we can’t look at yard plants as being too small scale to matter; only too many of the invasives got loose from gardens. I buy a Norway maple, you buy Norway maple, and then we’ve got a forest full of them. Why would the nativar-local genotype issue be necessarily different?

            • Vincent Vizachero says:

              As a rule, your level of concern about genetic introgression goes up in proportion to the level of immigration (how many “invaders” are brought in, and how quickly) and/or to the level of fitness differential (how able is the “invader” to out-compete the native species).

              Invasive plants are a problem precisely because they have a very high fitness differential: species like Norway maple, Japanese barberry, etc. can establish large populations here quite quickly with even a very low number of source plants because they out-compete our native species.

              It is very unlikely that non-local native plant would have such a high fitness differential over the local wild native plants. In fact, to the extent there is any differential it is likely to work against the non-local genotype (there is a good study on Androgon gerardii which found the non-local ecotypes to be less vigorous than local ecotypes in restored prairies). After all there is nothing to prevent a North Carolina genotype of bluestem from taking over a Maryland population in Maryland except for a lack of adaptation.

              Given that, it seems that it would take very high levels of (human-induced) immigration of non-local native plant genotypes to cause a problem for local populations. If the species is very rare or endangered, it could happen as a result of gardeners planting nativars I suppose. But it’s hard to imagine that even in such a case you’d be better off not planting the non-local native at all.

              Still, in the end I think we probably agree that the best approach is to use local genotypes as much as possible. I think that is the message we need to get out, and I’m glad you are highlighting it in your post.
              Vincent Vizachero recently posted..Want to Avoid Nativars? Look Here.

    2. UrsulaV says:

      I think this issue has the potential to be an important one. But I’m also a firm believer in not letting the perfect be the enemy of the good in this case…I think we’re close to a tipping point where many gardeners are starting to think of adding a few natives, and I fear to damage that fledgling enthusiasm by overloading them with too much “But not this! Or this! And you have to check this!” so that they give up and go buy boxwoods at Wal-mart because planting natives is way too complicated.

      It’s kinda like water conservation—I’d be happy if people just put up a rain barrel or stopped watering the sideway, I’m not going to demand that everybody install a grey-water reclamation system right off the bat.

      That being said, I do think it’s an issue worth exploring. While we’ll probably find out that 99 times out of 100, a coneflower’s a coneflower, that 1% is worth exploring. Much like those ugly double coneflowers that are so worthless for pollinators, we may find that other cultivars have more subtle failings, and it would be good to know so those of us who are more intensely involved in with natives can keep an eye out.
      UrsulaV recently posted..Io Moth Caterpillar

      Reply
      • Sue Sweeney says:

        It also good to know so that we’re not telling well-meaning people looking for advice on how to do the right thing by the wildlife that nativars are “just as good” when that might not be the case.

        Further, people can upgrade from a rain barrel to a grey-water reclamation system but we can’t, no matter how hard we try, eradicate most undesired plants once introduced into the environment.

        Reply
    3. Donna@ Gardens Eye View says:

      Sue this is such an excellent post to think about. I know in my fledgling years of buying natives, I found in fact they weren’t local natives. Some were Nativars. So I think we need to continue to explore this area and see if we can’t get more growers to help the gardener get what they really need-natives that are local. As far as nativars, I will try to keep an eye on where the pollinators go. I think sometimes they visit and sometimes they don’t. This is such a big, important issue with so many pieces. Thx for the food for thought!!
      Donna@ Gardens Eye View recently posted..Thrive

      Reply
    4. Sue Reed says:

      Thanks, Sue, for raising these questions. The thing I love about this whole business of designing with and advocating for native plants, is that there’s such a wide range of possibilities in our thoughts and actions. Even if all of us support the goal of protecting ecosystem health, we still get to choose which path toward that goal is the one that works best for us. Twenty-five years ago when I started telling my clients that I would design their landscapes only with native plants, my clients would either look blankly at me, or they’d say, “so, no flowers?” Then some years later, a more common response was “okay, that sounds good.” Flash forward a few more years and now clients were asking specifically for natives. They may or may not have totally understood what this meant, but they were asking! And here we are today, with a few clients starting to ask, “is this a local genotype?” WOW. In my short lifetime, what a shift. Of course many people still don’t care about native plants, and others are actively opposed, but if Lowe’s is carrying a line of supposed natives, then our efforts are working. We just have to keep educating ourselves and our clients, and clarifying what we’re trying to do. Yes, sometimes it’s a nuisance that definitions are slippery. And darnit, new information keeps coming along that requires our attention. But these challenges add to the vitality of the work, and keep it interesting. And one thing’s for sure: we are succeeding. The discussions in this blog prove it.

      Reply
    5. Sue Sweeney says:

      I have had several comments about the Nativar Dilemma making it too complicated for the average home owner. Really? Why don’t’ we just present it as the better brand? Get that old snob appeal going!

      Reply
    6. Ellen Sousa says:

      This has been a really interesting discussion! It’s easy to see how the average person would blank on all this detail – I’m with Sue, I think people (unless they hold strong anti-{fill in the blank} opinions about environmental issues, are usually just looking for guidance on the “right thing to do”. Look how popular the American Beauties nativar marketing program has been…what would it take to establish more regional programs such as “New England Beauties” or “California Beauties”? Package it in a way that people can understand it (ie. Buy Local), and you won’t have to explain the gritty details about why local genotypes are potentially much more important to preserving biodiversity.
      Ellen Sousa recently posted..The Year I Shall Win the Pachysandra War

      Reply
    7. Julie Serences says:

      Very interesting discussion. Folks in the Sacramento Valley Native Plant Society are actively letting others know to ask questions about plants they sell as natives. We have are lucky to have our own CNPS Elderberry Farms Native Plant Nursery – focus on seed collection and propagation from our own American River watershed plants. Gracious, but we need more research !!!!
      Thanks so much to you and for all of those who commented for sparking a debate here in California.

      Julie Serences

      Reply
    8. Loret says:

      It will take me a while to absorb all the information everyone (slo’ reader)! Since I live in a rural location with not your basic backyard and scads of threatened species of plants on my very own street, I guess my concern is justified for my situation. This certainly is a fascinating subject and thanks to Sue and Vince for bringing it to the forefront. I’ve so much to learn and this sure helps in that regard!
      Loret recently posted..The Sulphur Butterfly Emerged Already!

      Reply
    9. Ruth Parnall says:

      One more reason to advocate for careful site planning in order not to destroy the local native genotype. Much harder to replace what has been removed than not to remove it in the first place.

      Reply
    10. Benjamin Vogt says:

      That 2nd to last paragraph is key for me–houses on acreages suddenly appearing amidst already-degraded wild habitat, and then the inevitable will happen. Part of me really wants to say, look, it’s all over but the curtain. I’m not saying plant whatever, but getting as close as we can is the best we can do, even if that means I plant an Iowa bluestem instead of a Nebraska bluestem (I live in Nebraska). It’s argument worth having, though.
      Benjamin Vogt recently posted..Pieces of Monarchs

      Reply
      • Sue Sweeney says:

        “the best we can do” will better every day with all these great minds sharing ideas.

        Reply
    11. Kathy @nativegardener says:

      Great conversation. Thanks, Sue for bringing it up.

      I buy native seedlings from native gardens like Theodore Payne Foundation, or from the Cal Native Plant Society sales. I know these plants were grown from local seeds or cuttings. Perhaps we can suggest to folks that they look for these kinds of sources in their area instead of running to the same place they buy their snapdragons. :-)
      Kathy @nativegardener recently posted..CA Event: Native Plant Presentations San Luis Obispo Botanic Gardens

      Reply
      • Sue Sweeney says:

        Kathy – I couldn’t agree more. I wish every area had reliable native plant sources. What would be wonderful, I think, is if the local nurseries would start buying wholesale from the native plant people so this choice was offered at the local nursery.

        Here in CT, there are only a couple of good native places (e.g Earth Tones Nurseries) and they are so many miles away from the heavily-populated southern part of the state that I’m reluctant to encourage people to use so much petroleum just to buy garden plants, even if native ones.

        Reply
    12. Sue Sweeney says:

      If you’re exploring the in’s and out’s of nativars, make sure to also look at the postings about nativars by other NPWG authors, including:

      http://nativeplantwildlifegarden.com/native-plant-cultivars-gone-good/
      http://nativeplantwildlifegarden.com/planting-the-green-roof-what-is-a-native-plant-really/

      and there are more!

      Reply

    Trackbacks

    1. A Very Berry Time of Year says:

      [...] landscape. And certainly local herbivores (mostly local insects which are important bird food) are more likely to prefer the locally-grown native winterberry foliage as a food source. If you grow winterberry, please share your observations on the cultivars that [...]

      Reply
    2. NATIVE NEW ENGLAND WINTER COLOR says:

      [...] well and holds fruit through winter providing important support for wildlife. Here’s one “nativar”  that even this purist will readily embrace, provided the gardener can lay off the chemicals and [...]

      Reply

    Speak Your Mind Cancel reply

    *

    CommentLuv badge