During the growing season, I was charged with the fun and interesting task of compiling a list of all plant species growing in the Museum’s “habitat vignettes”. For those unfamiliar with this term, we sometimes use it to refer to areas of the museum grounds where we’ve worked to recreate plant communities that were typical of our area before European settlement. Frequent visitors know these areas well: the Black Oak Savanna, Burr Oak Savanna, Elizabeth Plotnick Tallgrass Prairie, the rooftop garden, (the section visible from the Bird Walk) and our portion of the North Pond edge.
In creating the plant list, I counted species intentionally planted by us as part of our restoration efforts as well as those that showed up here on their own. The total number of species was 350! Being in list-making mode, I divided these into categories that had more meaning in relation to what we are trying to accomplish with the habitat vignettes. To wit:
Native Species: 229
Planted by us: 159
It’s worth noting that these categories are not cut and dried distinctions. There are differing opinions on whether some species grew here before Columbus. Also, several have strains both from North America and from other continents (which can behave differently ecologically). In these cases, I tended towards the majority opinion of authors who have studied our local flora, weighted by my own opinion. Then there was the matter of how local to get while defining “native.” In this case, I considered a species native if it was known from a county at least bordering Cook.
A final distinction I wanted to make was whether a species was invasive or not. This entered even blurrier territory as, aside from a few of the worst offenders, there is far from a standard consensus on which species are invasive locally. I used a pragmatic approach, counting any species as “invasive” if we have actively attempted to control or eradicate it. The resulting list included 63 species – 12 of them native, 51 non-native. (Yes, native species can be invasive, too. But that’s a subject for another blog post.)
Willow Herb, Courtesy of Frank Mayfield via Wikimedia Commons/cc-by-sa-2.0
In creating any such list, there are bound to be surprises. For example, I found two native species of Willow Herb in the Black Oak Savanna that are more typically found in wetland habitats. I suspect that seeds or seedlings of these plants arrived in the soil of native plant plugs. (We happened to see Willow Herb growing in abundance at a local nursery). I was also surprised that one of the species we’ve attempted to reintroduce over the years – Marram Grass – seems to have died out completely. It almost certainly grew here centuries ago when lakefront dunes made up portions of the museum grounds, but now its failure here is a good example of the challenges posed by “restoring” nature in heavily modified environment.
Marram Grass, Courtesy of UIC
It is impossible to know the exact species list that would have emerged if I had compiled it a few centuries ago. Historically, this land was sand dune, marsh, oak savanna and probably some prairie. The lakefront was originally much closer to the museum. The topography, hydrology, and soil here have been drastically altered over the last couple centuries, making it difficult to recreate the conditions required by some of the presumed original species. Despite this, both the museum and the North Pond Nature Sanctuary have successfully reintroduced a good number of plants that once would likely have grown here. Have any of these original species survived on the property on their own throughout all of these changes? The answer, sadly, is probably not. However, some native plants were likely in the general area the whole time and would have been able to easily re-colonize the museum grounds. These correlate to the 56-70 species that I’ve listed as spontaneous. Why did some species need to be replanted, while others came back uninvited?
You may know that some plant species are extremely sensitive to specific conditions (like Leadplant), while others will grow almost anywhere (Hairy Aster). There is a general spectrum between these two extremes. The species we intentionally replanted tend towards the more conservative, “specialist” side, while those that found their own way here are on the other, “weedier” side. Another way to describe this equation ecologically is that climax species are on one end, and pioneer species are on the other. Pioneer species do well in disturbed areas where bare soil is exposed. This situation always existed in nature but is far more common today, as a result of human land use patterns. As a result, the seeds of these species are practically everywhere. But unlike these weedier species, when more conservative, climax species have been absent for a long while, their seeds are no longer in the soil (or in nearby areas), and thus they generally will not return on their own.
This list might be considered a “snapshot” of what was here in 2014. While I was positively surprised by the ratio of native to non-native species growing here, it should be noted that the species list doesn’t reflect how many individual plants of each species are present, which is what we hope to alter most as the years go by. The quantity of individual, reintroduced native plants will hopefully increase with time. The number of weedy native and non-natives will probably also change, as we extirpate some, and new ones arrive. Now that we have a list, we will be able to compare it to lists of future years, hopefully showing progress as we strive towards recreating lost native habitats.
Want to check out the list for yourself? You can view and download a PDF of it by clicking here.