Coreopsis and cosmos as natives
Hello there! my name is Adriana. My husband and I are working towards a pollinator friendly garden at our home in Frederick. I also happen to be a natural yarn dyer and wanted to ask about species of coreopsis and cosmos I cultivate for dyeing. In looking at the Maryland plant atlas I'm not seeing any species of either coreopsis or cosmos located in Frederick, but I grow coreopsis tinctoria and cosmos sulphureus (for dye) as well as cosmos bipinnatus, and an unidentified species of coreopsis I purchased at a farmers market. My question is, would these count as native species towards a pollinator friendly garden? I see lots of bees and butterflies loving on them but want to make sure these are accepted as native - Thank you so much!
Frederick County Maryland
Although two species of Cosmos (including sulphureus) are documented as occurring sparsely in Maryland, they are not native here. There are at least six species of Coreopsis occurring in Maryland, but as you discovered, although Coreopsis tinctoria is found here, it is not native:
Although C. tinctoria occurs nearly nation-wide at this point in time, its original native range was in the great plains and possibly the southeast.
What constitutes native depends greatly on who you ask, as various groups will have different definitions. Typically, it not only refers to species present in the U.S. or North America prior to European settlement, but also to the locations of species at that time and not to places they have since spread (usually human-assisted). Therefore, while Coreopsis tinctoria and Cosmos sulphureus are natives to this continent, they would not be considered native here in the mid-Atlantic as they were not part of our local ecosystem. Similarly, some native plant enthusiasts and ecologists do not consider cultivars of native species to be native, even if the parent species is. The presumption here is that their ecosystem function may have changed enough that they no longer benefit their environment. One example is a flower which has been bred to have extra petals at the expense of pollen. The validity of the assumption that they are less useful to wildlife depends greatly on what modifications the plants have and even what species they are; Mt. Cuba, a native-plant garden in Delaware, has done some studies on pollinator visits to species vs. cultivars and have seen mixed results rather than a trend of lessened value from cultivars.
Your plantings are certainly pollinator-friendly as evidenced by their high visitation, and thus far neither species has been an aggressive invasive weed here, so in a big-picture view, are probably largely harmless to have.
If you are curious, another reference you can check in the future (there are several and here too they won't all exactly overlap their species lists) is the Maryland Biodiversity Project, which collects image records of species found growing "wild" (not planted) in Maryland. As it is meant to document and help identify all forms of life found here, they list native and non-natives alike, with a notation in red text at the top of the species page for those which are not native. Here is their main page: https://www.marylandbiodiversity.com/
This is a plant list for MD compiled some time ago and available through the MD Native Plant Society, if you're curious in the future about what is considered native: https://mdflora.org/Resources/Publications/SurveyData/mdchecklist.pdf
THANK YOU so much for your thorough response and all the links for further information. I truly appreciate you taking the time to provide me and others with the best feedback to make sure we take care of the land around us!
You're quite welcome!