Native Cultivars Good, Bad, and Ugly

Native plant cultivars are a vexing topic.  My experience has been that gardeners who are increasing their use of native plants are likely to find the topic of native plant cultivars to be confusing, and for good reason.  There is a tremendous amount of variation in the traits for which cultivars are maintained, how the cultivars originated,  and in how cultivars are propagated.

Echinacea Coconut Lime cultivar, image copyright William Cullina

Most people take the term “cultivar” to be a contracted version of the phrase “cultivated variety”, a phrase which carries with it the structure of a most basic definition.

Cultivars are plants which are selected and/or bred by humans based on one or more specific traits, and which are then propagated in such a way that those traits are maintained. In other words, cultivars differ from “typical” examples of the plant species to which they belong AND that difference is important enough to somebody that the person is willing to expend time and energy to preserve the difference.  Cultivars are often maintained because they have an unusual flower color, leaf color, growth habit, or disease resistance.

There are three different ways in which a cultivars can first arise.  The first, and oldest, method is selection, in which an individual plant (or population of plants) naturally exhibits an atypical appearance or behavior.  Someone notices, and propagates that plant in such a way that the atypicality is preserved.  The second method is hybridization, in which two different species or varieties of plants are bred and their offspring is propagated.  Some cultivars are naturally occurring hybrids, found in nature at the boundary between two closely related species, but many cultivars are created at nurseries by plant breeders.  The third method is genetic engineering, in which humans directly manipulate the DNA of plants to produce some desired trait. If we limit our attention to cultivars of native plants, we can ignore genetic engineering since it is restricted because of expense largely to medical, industrial, and agricultural applications.  Most cultivars of native ornamental plants are either selections or hybrids.

Ilex verticillata, image rights reserved wallyg

Finally, there are two basic ways that the valuable traits of a cultivar can be maintained:  the cultivar can be propagated through cloning or it can be grown from seed.  Most cultivars of native plants (about 70%) are genetic clones, which means that each plant has exactly the same DNA.  The clones are grown by cuttings, by division, or by tissue culture. Some cultivars will grow “true” to seed, which means that seedlings will have the same important trait as the parent.

Okay, that’s a lot of background:  why does any of it matter?

When you are trying to decide on a native plant for your garden, all of these details can potentially help you decide whether or not a cultivar is the “right” choice for you.

1. Cultivars look different. Almost by definition, cultivars do no look like “normal” or “typical” examples of a plant species.  If they did, there would be no need to mess with a cultivar.  Whether or not this matters to you is, well, up to you.  If you want to plant Ilex verticillata, or Winterberry holly, but the ten foot mature height is a problem then maybe the cultivar Red Sprite at a mature height of four feet is exactly what you want. On the other hand, if your goal is to accurately represent the native flora of your site then a dwarf cultivar may be suboptimal.

2. Cultivars have less genetic diversity. This is a tricky one, because there are no hard-and-fast rules:  even some plants that are NOT marketed as a cultivar are actually propagated clonally:  if you care about genetic diversity, you have to ask your grower whether the plant was grown from open-pollinated seed (and make sure your grower has a firm and nuanced understanding of what this means). Open-pollinated seed collected from remnant wild populations is the gold standard, but not common.  Genetic diversity is a valuable insurance policy, since a diverse population has an increased probability of resisting threats from disease and/or pests. Another wrinkle is plant gender.  In some cases, like our native inkberry (Ilex glabra), every single commercially available cultivar is female.  Without male plants around, there will be no fruit on these hollies.

 

 

 

 

Physocarpus opulifolius Diablo, image rights reserved dragontoller

 

 

 

3. Cultivars behave differently. Because cultivars have been selected primarily on ornamental traits, it is not always clear whether or not they perform the same ecological role as the native plant species.  In many cases they do not.  For example, Echinacea cultivars have become nearly a fad and some examples are quite bizarre in color or in flower shape.  These Echinacea cultivars are sometimes sterile (bad news for goldfinches, who want the seed) and often have a “doubled” flower form (bad news for pollinators, who can’t effectively reach the pollen and nectar).  Another example is Eastern ninebark (Physocarpus opulifolius), the most popular cultivars of which were selected for dark (i.e. purple) foliage instead of the normal green.  It turns out, the “improved disease resistance” of the dark-leaved cultivars like Diablo and Summer Wine results from the specialist native ninebark beetle (Calligrapha spiraeae) finding the cultivars to be an inferior host, since the leaf chemistry of the cultivars differs in important ways from the species. Another potential problem with native cultivars is fruit (e.g. berry) size:  many culitvars were selected for bigger and/or more fruit, which may be nice to look at but may also be inedible to wildlife.

So, what is a native plant gardener to do?

I have planted, and will probably continue to plant, cultivars of locally native plants.  However, my first choice will always be a locally-sourced open-pollinated seed-grown plant.  My second choice will be a cultivar that maintains the flower shape, berry size, and leaf color of the species. My goal is to never buy cultivars that exhibit radically different flower shape or color, but I will knowingly buy dwarf varieties which are otherwise similar to the species. And when I see a cultivar touted as resistant to insect damage, that one gets an automatic rejection.

I also pay extra attention to observing my cultivars in the garden:  if I don’t see pollinators on the flowers, or insect damage on the leaves, or birds eating the fruit then I am quite likely to rip out the cultivar and try the species.  This is my policy because my primary motivation for using natives in the first place is that I want to support my local ecology.  If I can’t see evidence that a cultivar is helping me accomplish that goal, I fire it and hire a plant that will.

 

© 2011, Vincent Vizachero. 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

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    About Vincent Vizachero

    Vincent Vizachero is a native plant advocate and consultant in Baltimore. His focus is on lecturing, environmental education, social media management, and grant-writing. You might think the fact that studied Economics at the College of William & Mary in Virginia and Finance at the University of Chicago Booth School of Business would make him a bit of a geek. You'd be right. You can keep up with him on Facebook and Twitter.

    Comments

    1. Heather says:

      Great post Vincent. I have been meaning to investigate information about the Ninebark cultivars. I have the species Ninebark as well as a few Diablo near the street. I have debated on removing them for they are the only native cultivar in my yard, and to me they look so out of place. The foliage colors in the landscape trade are so obnoxious, the bright golds, wines and lime greens. I think theres much to appreciate in the simplicity of our native plants and the subtle differences in open-pollinated seed grown plants. One of my favorite growers collects seed within a 50 radius of his nursery.
      Heather
      Heather recently posted..Robber Flies- Wolves in Sheeps Clothing

      Reply
      • Vincent Vizachero says:

        Thanks for the compliment, Heather. This topic is a big one, and I hope I at least achieved coherency!

        The ninebarks were a tough example, since the purple-leaved cultivars have all but completely replaced the (more normal) green-leaved varieties in the commercial trade. I suppose I would prefer that someone plant a native cultivar than a non-native, but I would prefer that people have choices even more.

        I also get sad every time I see a purple-leaved Eastern redbud.

        Reply
    2. Sue Sweeney says:

      Good work Vincent. Getting people to understand that nativars are not necessarily native or good for the ecology isnt easy.

      Reply
    3. Sue Reed says:

      Thanks, Vincent, for clarifying this important subject!

      Reply
    4. Benjamin Vogt says:

      Those newer coneflower cultivars are crap all the way around, living out their short lives like the first drafts of a Frakenstein man. There are plenty of species cones with enough variety to satiate folksunless they do really like that fluffy mounded quadruple petal junk. I have a Coppertina ninebark, and pollinators love it. Not much leaf damage, though. Im for letting cultivars revert back to species (that IS how it works, right?), and let them do their thing. I think, though, we wont see any change in consumer buying habits towards native species, because there arent any in nurseries. Whens the last time you saw an ozark or reflexed coneflower for sale in person? Native elderberry?
      Benjamin Vogt recently posted..Tour My Garden Pics amp Video

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    5. Gloria says:

      Helpful information. A question about seedlings that sometimes self sow around these cultivars(although I have noticed many are sterile or nearly so), are they reverting back to the species when you see the leaf color and size or blossom are back to normal?

      Reply
      • Vincent Vizachero says:

        Ill throw out the caveat again about there being no hard-and-fast rules, but basically I would answer yes, possibly. If the cultivar has been propagated vegetatively, then the chances are good that the seed-grown offspring will perform their ecological function better than the cultivar itself did. I wouldnt go so far as saying they will go back to normal, necessarily, if only because you will probably still have a severely inbred population unless you have a genetically diverse population nearby as part of the breeding pool.

        Reply
    6. Genevieve says:

      Benjamin, youre highlighting the issue with natives for me theyre not available! I design them in for a clients landscape, and I cant fricking find the plant thats growing along the side of the roads! Irony, hey? But I can find the purples, the rufflies, the funny colors. And I love that stuff, but Id also like to be able to plant the normal one, too, particularly, as Vincent points out, when there is compelling reason to prefer the usual one, which is often. Its a shame.

      Vincent, great article, you answered a number of questions for me and clarified a great many points.
      Genevieve recently posted..Deer-Resistant Plantings You Can’t F Up

      Reply
    7. Loret T. Setters says:

      What a wonderful article!

      My personal experience:

      I purchased the wildflower gaura at a master gardener plant sale. Then I found some naturally occuring on my rural property. What a big difference in the look and in the usage by native insects. The naturally occuring wins hands down in the benefit to wildlife, although Im sure there are gardeners who would opt for the one cultivated to produce more prominent blooms.

      I find it sad that some choose their own needs over the needs of mother nature. Glad to see you bring to the forefront the importance of paying attention to what best benefits wildlife and rethinking what we plant if it doesnt measure up.
      Loret T. Setters recently posted..The Blur of the Butterfly Missed Opportunity

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    8. Beatriz Moisset says:

      Excellent information and good advice. I hope that many read this article and pay attention to it. Thanks.
      Beatriz Moisset recently posted..Rain and Pollinators

      Reply
    9. Suzanne says:

      This article should be titled, When a Native isnt a Native. I appreciate the clear explanation regarding Whats a cultivar but wonder if a cultivar of a native can be considered a native plant, truly. I mean, where does the definition of native end and cultivar begin? Does cultivar equal native simply because it originates from a native plant? The three ways in which a native is cultivared so clearly explained is very much appreciated. And, observation of the garden as a clear definer of a healthy ecology, top notch. Thank you.

      Reply
    10. Megan says:

      I really appreciated this post- have wondered about these cultivars for years and felt suspicious. Your guidelines seem smart and sensible.

      Thanks!
      Megan
      Megan recently posted..Companion planting to end Japanese beetle descent

      Reply
    11. Pat Sutton says:

      Great piece, Vincent. Toooooooooooo many people never give it a thought and wonder why their recently purchased garden gems arent drawing in insects. So much education to do! Thanks for covering this important topic so well! Love your ending. I too have no patience for plants just taking up space.
      Pat Sutton recently posted..2011 Wildlife Garden TOURS

      Reply
    12. Beatriz Moisset says:

      One case in which cultivars are not only justified but a necessity is when the native species is going extinct because of an introduced invasive pest. I am all for creating cultivars of elms, American chestnuts and hemlocks. That is probably the only way to save them from Dutch elm disease, chestnut blight and hemlock woolly adelgid. How long will that take? Sigh!

      Reply
      • Vincent Vizachero says:

        Thats a great point, Beatriz! I have been using Princeton and Valley Forge elms quite happily, and cannot WAIT for the day we have commercially available blight-resistant chestnuts. Literally, I cant wait: Im growing non-resistant American chestnuts as a host plant, knowing full well they will one day succumb to the disease.
        Vincent Vizachero recently posted..Want to Avoid Nativars? Look Here.

        Reply
    13. Carole Sevilla Brown says:

      Great article, Vincent! This is a discussion that needs to go much further. Thank you so much for beginning it with such clarity. One trouble with cultivars is that when you change the appearance to the extent of creating extra petals often native pollinators are unable to reach the nectar, and also because the plant is putting so much extra energy into those double and triple flowers, the nectar is no longer a high quality source.
      Carole Sevilla Brown recently posted..Do Black Swallowtail Catepillars Lay Their Eggs on Dill

      Reply
    14. Carole says:

      I have a cultivar of lyre-leaf sage. I wonder what will happen when a pollinator distributes pollen from the cultivar to the natives and they produce seed. Will I have affected the native plants with my purchase?

      Reply
      • Vincent Vizachero says:

        Carole, I wouldnt worry much about your cultivar polluting the gene pool of Salvia lyrata. Im guessing your cultivar is a purple-leaved variety, and if so it likely grows true from seed. This typically indicates that the cultivar is genetically stable, and many sources would consider it a variety (aka sub-species) as opposed to a much less desirable hybrid. While a more normal looking plant would probably have better wildlife value, it is quite unlikely your cultivar will do any harm to existing natural populations.
        Vincent Vizachero recently posted..Why is Anise-scented Goldenrod so rare?

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