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Native Cultivars vs. Native Plants & Their Attractiveness to Pollinators

As you start shopping for plants this spring, please emphasize regional native plants that support your local ecosystem.  That sounds easy, doesn’t it?  Well, it’s actually a bit more complicated.   Sometimes the only native plants you can find are native cultivars, not open-pollinated, “straight species” natives.  These native cultivars are often referred to as “nativars.”

For those of you who are newer to gardening, here is an example.  The straight species of Purple Coneflower is Echinacea purpurea.  Echinacea purpurea ‘Magnus’ is a cultivar, a plant that has been selected by man for certain traits and propagated to keep those traits.

Why does this distinction matter?  For one thing genetic diversity is the foundation for biodiversity, which is the foundation for healthy ecosystems.  Open-pollinated, straight species natives provide this genetic diversity;  native cultivars do not.  Finding locally grown straight species natives, is another key to supporting local ecosystems.

When you visit large wholesale growers, retail nurseries, or big box stores, the selection of native plants may be quite limited, and often a cultivar may be your only option.  This is troubling, since it seems like the same cultivars of the same plants are offered absolutely everywhere.  So much for genetic diversity!

Besides diminishing the genetic pool, there is another concern: do native cultivars provide the same ecological function in nature?  We can figure some of this out through logic.  For example, a sterile cultivar that does not produce seeds, will not feed seed-eating birds.   It gets trickier when we start to factor in pollinators.  We can often see which plants attract more insects, but that is the tip of the ecological iceberg.

There is exciting new research being conducted by Annie White, a PhD student in Ecological Landscape Design at the University of Vermont.  Under the guidance of Dr. Leonard Perry, White is comparing what she calls “true open-pollinated native wildflowers” to native cultivars, in terms of their ability to attract and provide nectar and pollen resources to pollinators.

It appears that Annie White may be the first person to ever research this topic.  Very timely research it is, with native bees, honey bees,  and other pollinators facing serious challenges.   White started her data collection in 2013, utilizing two research sites she established in Vermont.  She has been studying 14 flowering perennial plants that are native to the Northeast, comparing each to a native cultivar.  In the case of Echinacea purpurea, three cultivars were studied.

White observed pollinating insects visiting these plants.  She recorded visits by native bees, honey bees, wasps, beetles and butterflies.  White is most interested in bees, of which there are 275 species in Vermont.

Here is the list plants which Annie White is currently researching:

Achillea millefoliumCommon Yarrow
Achillea millefolium ‘Stawberry Seduction’Strawberry Seduction Yarrow
Agastache foeniculumBlue Giant Hyssop
Agastache foeniculum ‘Golden Jubilee’Golden Jubilee Hyssop
Aquilegia canadensisWild Columbine
Aquilegia canadensis ‘Corbett’Wild Columbine
Asclepias tuberosaButterfly Weed
Asclepias tuberosa ‘Hello Yellow’Butterfly Weed
Aster novae-angliaeNew England Aster
Aster novae-angliae ‘Alma Poetschke’New England Aster
Baptisia australisWild Indigo/Blue False Indigo
Baptisia ‘Twilite’ Prairie BluesFalse Indigo
Echinacea purpureaPurple Coneflower
Echinacea purpurea ‘White Swan’Coneflower
Echinacea  ‘Sunrise Big Sky’Coneflower
Echinacea purpurea ‘Pink Double Delight’Pink Double Coneflower
Helenium autumnaleCommon Sneezeweed
Helenium autumnale ‘Moerheim Beauty’Sneezeweed
Lobelia cardinalisCardinal Flower
Lobelia cardinalis ‘Fried Green Tomatoes’Cardinal Flower
Monarda fistulosaWild Bergamot/ Bee Balm
Monarda fistulosa ‘Claire Grace’Wild Bergamot/ Bee Balm
Penstemon digitalisBeardtongue
Penstemon digitalis ‘Husker Red’Beardtongue
Rudbeckia fulgidaBlack-eyed Susan
Rudbeckia fulgida ‘Goldsturm’Black-eyed Susan
Tradescantia ohiensisSpiderwort
Tradescania ‘Red Grape’Spiderwort
Veronicastrum virginicumCulver’s Root
Veronicastrum virginicum ‘Lavender Towers’Culver’s Root

To date, the research results are species-specific, with some plant pairs showing dramatic differences in each plant’s ability to attract pollinators.  Echinacea purpurea ‘Pink Double’ did poorly compared to the straight species, while Echinacea purpurea ‘White Swan’ did rather well.  For complete results on all the plants, please watch the accompanying video or listen to the podcast.

White’s research will continue in the growing season of 2014.  EcoBeneficial! will cover her progress and report on the results.  For more information on Annie White’s research, please visit www.pollinatorgardens.org

From Kim Eierman at EcoBeneficial!

Photo:  Annie White in Research Mode
Photo: Tim White