When are native plants not native?
As pollinator-friendly gardening increases in popularity, more nurseries are offering “nativars.” Is a native plant species the same as the nativar variety? What is the difference between natives and nativars? Will nativars support pollinators as well as their native counterparts?
A native plant species is one that has evolved in an ecosystem prior to human settlement. These species are open-pollinated by insects, birds, and wind, and occasional human assistance, resulting in growth characteristics that stay true from one generation to another.
As a result, pollinator species have evolved alongside native plant species and have formed specific relationships with those native plants.
The most well-known example is the common milkweed (Asclepias syriaca) and the monarch butterfly (Danaus plexippus) that requires milkweed as food for the caterpillar stage to complete its life cycle. Many other species have the same lineage pairings: spicebush (Lindera benzoin) and the spicebush butterfly (Papilio troilus), and white turtlehead (Chelone glabra) and the Baltimore checkerspot (Euphydryas phaeton).
A “nativar” is a cultivar of a native plant. The nativar has been developed with human assistance to maintain certain plant characteristics such as disease resistance, leaf or flower color, height, or more complex blooms with more petals.
Although genetic variation occurs in nature and can be passed on from one generation to another, the human manipulation undertaken in producing nativars results in a plant cultivar containing the exact same genetic material (clone). Nativars may not be as resilient to environmental change, such as drought or early weather freezes.
Natives, however, have diverse genetics, adapting through genetic changes to environmental challenges. Over time, native species can continue to adapt through genetic change.
Because the nativar of a native species has the same DNA from one generation to the next, it does not always offer the same benefits for native pollinators that evolved with the native species. The ability of native pollinators to use a nativar depends on the genetically selected trait to create the nativar. Leaf color has been found to affect the ability of caterpillars to feed.
For example, common nine bark (Physocarpus opulifolius) as a straight native species has green foliage and is a host for moth species such as the Io moth (Automeris io).
However, a nativar of common nine bark with dark red foliage contains anthocyanins, water-soluble pigments in the red foliage that make the leaves indigestible to the moth caterpillars.
Other cultivars may have “double-petaled” flowers that appear beautiful but make it impossible for butterflies and other pollinators to find nectar or pollen because the reproductive organs within the flower have been reduced or replaced by additional petals. The double petal nativars of purple coneflower (Echinacea purpurea) do not provide nectar or pollen as effectively to visiting pollinators as the native species. Similarly, petal color alteration can also change the usefulness of a flower for pollinators.
Research indicates that coneflowers with orange or white petals were found to be less frequently visited than the native, purple coneflower. In some instances, there is concern that nativars may cross-pollinate with nearby native species and reduce the genetic variation of the native species.
There are instances where nativars have been developed that appear to have no significant difference in how pollinators use the nativar versus the native species. Those that are cultivated as shorter “dwarf” nativars but retain all of the other native characteristics may be fine to plant in your landscape or garden.
New England Aster (Symphyotrichum novae-angliae “Purple Dome“) has a shorter, mounded growing habit than the native species and could be a consideration for a small garden or container.
A few nativars studied in plant trials at Mt. Cuba Center have also been shown to attract more pollinator visits than the native species. Phlox ”Jeana“ (Phlox paniculata, ”Jeana“) and two bee balms (Monarda didyma, ”Jacob Kline“ and Monarda fistulosa, ”Claire Grace”) performed better than the native species in the trials.
In the case of the bee balm, both nativars also had better resistance to mildew and longer lasting flowers. “Jacob Kline“ was outstanding in attracting hummingbirds.
What does choosing a native or nativar mean for the pollinator gardener? If your goal is to attract native pollinators and help sustain their populations, do your research before purchasing perennials and garden plants.
Search online for plant/pollinator trials undertaken by researchers for the plants you are contemplating and consider their results. Read the plant tag before purchasing a particular plant.
Besides the common name and growth conditions, the scientific name (in italics) may have another name in quotes, which is the cultivar/nativar name. Reviewing this information will help you search for the nativar you want to purchase or avoid.
If you have questions about native plants or pollinators, telephone the Penn State Extension Master Gardeners of Butler County at the Garden Hotline at 724-287-4761, Ext. 7, or email the Master Gardeners at butlermg@psu.edu.
