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New Studies Weigh Ecological Value of Native Cultivars - Wild Roots
I recently wrote about the key differences between native cultivars and straight species and why we should care. My conclusion was that while it wasn’t necessary to completely eschew cultivars of native species (sometimes referred to as nativars), if you wanted your garden to provide crucial ecosystem services, like supporting pollinators, you should be sure to include a significant number of straight species plants, ideally from local ecotypes, or geographic origins, if possible. It makes intuitive sense that if you want to support wildlife and natural processes (and you should!), you’d want the plants you select to reflect those processes, as opposed to choosing genetically indistinct clones that may exhibit unusual characteristics. But is there a scientific basis for this? Luckily this is a question that a few intrepid scientists are beginning to address. Doug Tallamy, entomologist and celebrated author of Bringing Nature Home, has been studying caterpillar interactions with native plants and their cultivars alongside graduate student Emily Baisden at Delaware’s Mt. Cuba Center. And Annie White recently completed doctoral research at the University of Vermont which tracked pollinator visits to straight species and cultivars in the context of pollinator restoration projects. Hopefully this will be the start of even more robust research, but early results, which should be of great interest to land managers, the ecological restoration community, and even home gardeners, are highlighting the value of straight species while not dismissing cultivars out of hand. Tallamy’s findings are preliminary, but they show that different characteristics of cultivars can have different effects on how they fit into the ecosystem. In terms of cultivars with distinct plant size or habits, caterpillars had no preference between them and the straight species. The same went for specimens selected for disease resistance, which is good news for the folks working to restore elm and chestnut populations. Leaf color, however, was an area where differences started to come through. Cultivars with purple leaves, for instance, were not nearly as attractive as their green straight species counterparts. This could be the result of visual cues, or as Tallamy suggests, the unpalatibility of the specific chemical compounds that lead to those unusual colors. Variegation in leaves (streaks of color) was less conclusive. Some caterpillar species actually preferred the variegated cultivars, though most avoided them (and since they contain less chlorophyll, they’re probably less nutritious). White’s research in Vermont focused not on caterpillars and leaves, but…