Let Natives Be Natives

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Throughout all of the preceding month, I’ve been mulling over a symposium I attended at the University of Connecticut on October 3rd.  Titled the “UConn Native Plants and Pollinators Conference,” it unintentionally highlighted a fundamental disconnect at the heart of contemporary gardening.

In the morning, the conference featured as a speaker Annie White, a landscape architect from Vermont who researched for her doctoral thesis the relative value to pollinators of species-type native plants versus “nativars,” cultivated selections or hybrids of native plants.  White found that sometimes, though not always, the species type plants were far more attractive to the pollinators.  I found that interesting.

Even more interesting, though, was the reaction of an afternoon speaker, a representative of the University of Connecticut faculty.  Dr. Jessica Lubell of UConn’s Department of Plant Science and Landscape Architecture  began by attacking Annie White’s data, insisting that unnamed studies had found that there was no difference in the benefits to pollinators provided by wild-type native plants and their cultivars.  She then went on to stress the importance of moving to the cultivars so that the nursery industry could continue to grow the plants – the natives now genetically identical and reduced to neat, compact mounds – in the same industrial way it has been growing exotics.  She also stressed that eliminating the genetic variability from native plants and reducing their size would enable gardeners to adopt them without rethinking at all their landscape aesthetic.  To accompany this, Lubell showed dozens of slides of emasculated natives growing as cushions and balls amid the usual seas of bark mulch.

Hydrangea arborescens nativars ‘Invincibelle Ruby’ and ‘Invincibelle Wee White’

It seems to me, given the crashing populations of birds and insects and the tidy ugliness of so many of our suburbs, that a reboot of our gardens is long overdue.  Reducing the genetic variability of the plants we cultivate directly contradicts the kind of resilience we need during an age of climate change and introduced pests and diseases.

In short, we badly need to re-examine our contemporary style of landscaping.  We need to reconsider our desire for predictable uniformity in our plants.  We need, above all, to come to terms with natural growth and not view our plants as some species of green outdoor ‘design elements.’

Credit: Rick Webb, PA
Hydrangea arborescens species type (photo courtesy of Rick Webb, PA)
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Thomas Christopher

My father was a compulsive tree planter, but it was my mother who taught me the finer points of gardening.

Her homeschooling was followed by two years in the New York Botanical Garden’s School of Professional Horticulture, and then ten years as horticulturist at an Olmsted Brothers designed estate on the Hudson River Palisades.

I’ve worked as a horticultural journalist for 30 years, contributing to publications ranging from Martha Stewart Living to the Journal of the Royal Horticultural Society and The New York Times.  My most recent book is Essential Perennials, a guide to the best contemporary perennial flowers co-authored with Ruth Rogers Clausen and published by Timber Press.  I’m currently working on a book about ecological gardening with Larry Weaner.

My special enthusiasms include sustainable gardening, especially sustainable lawns;  heirloom chicken breeds; and recreating vintage New England hard ciders.

 

Contact Tom by email

14 COMMENTS

  1. This is good information to know because I’m letting asters, solidagos, elderberries, and salvias to grow in my backyard, and they are all wild natives. They may be thugs, and they may end up taking over a bit, but the pollinators like them so I’m leaving them. When I purchased plants this fall, I specifically went to the Stephen F. Austin State University plant sale to buy natives, and they had a good selection. However, I won’t tell others to do as I do because I’m afraid they might not garden at all.

  2. In practice and by observation – I have found White’s evidence to be compelling. I heard her lecture a few years ago and have been observing native species and cultivars – there is no doubt in my mind that about 80% of the time, the species were more attractive to the pollinators.

  3. It seems reasonable to assume that just as fragrance was sacrificed in many rose hybrids to achieve larger, fuller blossoms, anthers were sacrificed in many flowers to produce more petals, and taste was sacrificed in many vegetables to achieve better shipping quality, that some selective breeding of native plants for more desirable form and flowers would lead to reduced nectar and pollen – the qualities needed by pollinators.

  4. Good grief! What’s next? People chopping their toes off because it’s easier for shoe manufacturers to just produce size sixes?
    The very idea that the garden/landscape/environment should be shaped according to what is convenient for industrial plant-production is so arse-about-face I am lost for words.

  5. It seems that there are two separate questions here that should be considered separately. One question is whether or not pollinators prefer native plants to cultivars of native species. The other question is whether or not cultivars should be preferred to their native relatives for other reasons, such as aesthetics or for genetic diversity.

    I attended the International Pollinator Conference at UC Davis in July. Academic scientists from 12 countries presented their studies. The word “native” was rarely uttered. With regard to resource preferences, pollinators benefit most from a diverse garden that prolongs the blooming period. Empirical studies do not find a consistent preference for native, compared to non-native plants, let alone between natives and their cultivars. Natives and their cultivars are chemically identical.

    There may be other reasons for choosing a “wild” native rather than its cultivar, but the preferences of pollinators is not one of them.

  6. It’s the wrong question, economically. It’s not really whether or not pollinators prefer native plants, which may be related to any number of factors of form, fragrance or color, the question is whether or not native plants allow better survival or sustainability of pollinators than cultivars (as long as sustaining native pollinators is the goal).

    But I also don’t question the need for diversity among plantings and species (disease control, etc), nor the need to care less about compact little obedient plants and more about letting plants have their own beauty.
    Noah’s Garden; author Sara Stein is perhaps one path to a better garden aesthetic….

  7. Douglas Tallamy makes a good argument for planting natives in that the appropriate natives not only provide floral nectar and pollen but also host plants for the larval stages of butterflies et al. He warns against planting some exotics, such as butterfly bush. Not only is that an invasive, but it attracts butterflies away from the native plants that not only feed them but also host their caterpillars. I also remember a lecture by Dr. Harland Patch of the University of Pennsylvania who discussed the fact that different pollens contain different amino acids and lipids and that native pollinators were typically adapted to the pollens of certain native plants and benefited the most from them. I will try to research this and post what I find.

    • Non-native plants are also host plants for lepidoptera. Here’s an article about monarchs laying their eggs on non-native milkweed. This article was published by UC Davis Bohart Museum of Entomology at UC Davis. https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=31244

      The fact is, insects don’t share the prejudice of humans against non-native plants. Why would they? In the case of the tropical milkweed, it is a particularly handsome species of milkweed and it is chemically similar to native species of milkweed. It’s brightly colored flowers of red and yellow are undoubtedly attractive to monarchs

      Now let’s consider the argument that we should not plant buddleia in our gardens because although it feeds butterflies, it isn’t their host plant where they lay their eggs. The problem with that argument is that it isn’t true.

      In 1940, Charles M. Dammers reported that the Variable Checkerspot (Euphydryas chalcedona) “can use” buddleia as a substitute for its usual native host in southern California desert-mountain areas, based on a laboratory study of the larval stages of its caterpillar on buddleia. In 2001, chemical analysis of buddleia found that it is chemically similar to the native host of the checkerspot, which confirmed the potential for such a substitution.

      The first actual observation of checkerspot butterflies breeding spontaneously and successfully on buddleia was in Mariposa County, California in the Sierra Nevada foothills. “Mariposa” is Spanish for butterfly. Mariposa County was named by an early Spanish explorer who saw many butterflies near Chowchilla.
      Checkerspot bred successfully on buddleia in 2005 and in subsequent years. This colony of checkerspot on buddleia was reported in 2009: “We conclude that buddleia davidii [and other species of buddleia] represents yet another exotic plant adopted as a larval host by a native California butterfly and that other members of the genus may also be used as the opportunity arises.” (Arthur M. Shapiro and Katie Hertfelder, “Use of Buddleja as Host Plant by Euphydryas chalcedona in the Sierra Nevada foothills, California,” News of the Lepidopterists’ Society, Spring 2009)

      The California Invasive Plant Council says in its inventory of “invasive plants” that buddleia is not invasive in California.

      Anise swallowtail butterfly uses exclusively non-native fennel as its host plant in California. Anise swallowtail breeds year-around in California because of the availability of non-native fennel. Because the native equivalent to non-native fennel is dormant half the year, the Anise swallowtail was not able to breed year-around prior to the introduction of its non-native host.

      There are many other examples of lepidoptera using non-native plants as their host plant. These are just a few.

      • Some lepidoptera can use non-native plants as larval hosts, but 90% of them are specialists — relying on just one or two kinds of plants on which to lay eggs. It’s critical to maintain and increase plantings of those specialist hosts to keep reproduction of caterpillar-producing insects from declining, which has been happening at an alarming rate for a while now.
        This is a strong argument for making some larval host plants a backbone of the garden. Then add well-adapted non-native plants as you like, or not.

        For pollinator levels, whether you’re growing mostly garden plants or local natives, the important thing is to have something always in bloom over a long, continuous season. It’s also helpful to have a broad variety of flower sizes. (These are reasons to get more kinds of plants, something most gardeners welcome.)

        • In “Non-native plants reduce abundance, richness, and host specialization in epidopteran communities” (Ecosphere, November 2010), Doug Tallamy and his co-author define caterpillars as “specialists” if they feed on three or fewer plant families. There are typically hundreds of genera in each plant family and thousands of plant species. For example, there are 20,000 plant species members of the Asteraceae family, including the native sagebrush (Artemisia) and the non-native African daisy. In other words, the insect that confines its diet to one family of plants is not very specialized.

          Insects can typically use any plant species within the same genus and usually within the same or closely related families. The plants are chemically and genetically similar and often morphologically similar. Some are native and some are non-native.

          The nativist viewpoint of nature exaggerates specialization and underestimates the speed of adaptation and evolution. Mutually exclusive relationships between one insect species and one plant species are extremely rare in nature because they are an evolutionary dead end.

  8. Thanks so much for this article. While I am now mostly planting natives on my 10 acres and letting the natives come back, I also have non-native perennials and some “nativars” closer to the house. However I have also found that the insects prefer the natives generally. I have also found that I can incorporate most natives if I chose carefully. Yes, some get too large to fit in my front yard but others don’t. Yes, I have had to move things around but then what gardener doesn’t.

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