Native plants and their native cultivars, sometimes called nativars, seem very similar, but are
they?
Nativars are often sold as being beneficial like native plants are, but with more choices, such as
different flower colours, bigger or more flowers, or different growing habits. It’s important to note,
however, that these are human-preferred traits. Ecological traits often get overlooked in plant
breeding, even though they are one of the most valuable aspects of gardening with native
plants. Value to pollinators is an example of an important ecological trait of native plants.
There has been recent research into the pollinator value of native plants versus nativars for
Pacific Northwest specific plants, making the results relevant to our gardens. One of the findings
in these studies was that a higher number of species visit the regular native species.
This matters because there are over 500 species of native bees in BC! Native bees are very
different from honeybees (a non-native, introduced species) because many are specialists,
meaning they evolved alongside native plants and prefer their pollen over other species.
These studies concluded that native bees prefer native species over nativars. This is likely
because plant breeding doesn’t take pleiotropy into account. Pleiotropy is when a gene affects
multiple traits. So changing a trait for flower colour, for example, may change a trait that makes
the flower unattractive or inaccessible to bees, or makes pollen less nutritious.
It’s interesting to note that there are different sources/types of nativars, and these may also
affect bees. Some nativars are interspecies hybrids, and would therefore likely contain
characteristics of plants native to two different areas. These are considered the most genetically
divergent from a native species. However, some nativars are selected from a naturally occurring
plant variation, such as a white flowered version of Douglas Aster (Symphyotrichum
subspicatum) discovered on Sauvie Island in Oregon. Plant breeders saved seeds from
vigorous plants and named their version ‘Sauvie Snow’. Studies found that native bees
preferred these less genetically-divergent cultivars over interspecies hybrids.
Lessons we can take from this research:
It’s important to know the outcomes of using cultivars of natives in the landscape, because in
crucial ways, they aren’t ecologically equivalent to each other. Researching origins of cultivars
to find ones that are less divergent genetically from our native species can lead to more
beneficial gardens. Before choosing though, I’d say give some of our native species a try! There
are so many beautiful options, especially for those tough spots in your yard where other plants
don’t seem to want to grow.
Check out the research yourself (open access):
OSU study part one: https://doi.org/10.1093/ee/nvae126
OSU study part two: https://doi.org/10.1093/ee/nvaf105
Please note: Although this study included California Poppy (Eschscholzia californica), it is
considered invasive in BC.
Whitney Peek, Master Gardener