Curtis Prairie Walk

Ox-eye (Heliopsis helianthoides)

Ox-eye (Heliopsis helianthoides)

About 30 of us meandered together through the famous Curtis Prairie this afternoon, witnessing many flowers blooming, or getting ready to bloom, and trying to name them all!

Of course native plants are not the only plants flourishing—as we witnessed today, many invasive species of plants are flowering, seeding, and growing, too. A trip into the Curtis Prairie leads to restoration reflections. Our group spent some time discussing what an invasive plant species is and the continued management required to keep these aggressive plants at bay. Invasive species are not all alike in the way that they outcompete and displace native plant species; different invasive plants employ different strategies to thrive. For example, we spent some time on our walk this afternoon discussing invasive honeysuckles. One of the reasons that honeysuckles have been labeled invasive and are restricted throughout Wisconsin has to do with how early these plants put leaves out in spring. They quickly create a shady canopy over our native shrubs, which have not yet had time to evolve with the aggressive honeysuckles, pushing the natives out of the habitat completely. This early leaf out is especially detrimental to Wisconsin’s ephemerals, which have evolved to complete their life cycle before the native shrubs and trees can create a canopy over them.

Unmanaged road median
Unmanaged road median

Someone in the group asked a good question about whether or not invasive species could be nature’s way to keep populations of native plants in check, and I want to reiterate that invasive species of plants do not keep a population of another plant species under control; they completely wipe out species of plants from an area. A good example of this is seen on many an unmanaged roadside median (see pic). Seen in this particular picture, we have a couple of regular roadside culprits like bird’s-foot trefoil (Lotus corniculatus) and chicory (Cichorium intybus), but no sign of any native plants. Many invasive plant species are known for thriving in manmade disturbed sites like roadsides, while many endangered species of native plants do not fare well in these conditions, especially under the pressure of exotic and aggressive plants. The Wisconsin Department of Natural Resources (WDNR) has a website and you are able to look through a long list of endangered and threatened species of plants in the state. The WDNR website is also an excellent resource for learning what species of plants in Wisconsin are listed as invasive and restricted. For example, they have a full brochure dedicated to invasive honeysuckles and it can give you the information you need to decide if you are looking at an invasive or native species of honeysuckle, as well as the best way to manage it on your property. A couple of good places to start are:

Rosinweed (Silphium integrifolium)
Rosinweed (Silphium integrifolium)

Since members of Silphium and Helianthus (the sunflower looking flowers) are starting to take off, we had questions about how to distinguish one from the other. I find putting together notecards with pictures for quick reference to be helpful, and of course a field guide is a wonderful tool for plant id. Using post-its to mark the “sunflower-ish” section of your field guide is helpful to find what you are looking for quickly while on your walk. One of these tricky-to-identify plants that we observed blooming this afternoon was the ox-eye (Heliopsis helianthoides)—distinguished easily from the rosinweed (Silphium integrifolium) we looked at by the leaves. On the rosinweed the leaves are opposite and stalkless, appearing to almost surround the stem (clasping), and often red can be seen on the stem. We also talked about the saw-tooth sunflower (Helianthus grosseserratus), which also sometimes has a red stem but very different leaves than the rosinweed: stalked and alternate.

There were a lot of questions regarding the invasive lilies that resemble the native and beautiful Michigan, or Turk’s-cap lily (Lilium michiganense), we saw blooming. The invasive orange daylily (Hemerocallis fulva) is commonly seen in Madison on many a front lawn, differing from the native Turk’s-cap most notably by its erect flower heads, while the native species flower heads are nodding. The WDNR has listed the invasive species with a “Caution” label, though sadly I do not believe the package of orange daylily seeds sold at the local gardening stores are labeled as such.

The spotted water-hemlocks (Cicuta maculata) were thriving and showy today, along with sumacs, flowering spurge (Euphorbia corollata), sedges, rushes, grasses, and milkweeds. An especially gorgeous talking point throughout was the deep purple/red of the swamp milkweed (Asclepias incarnata). Bee balm (Monarda fistulosa) was just starting to take off, along with purple coneflowers (Echinacea), Virginia mountain mint (Pycnanthemum virginianum) and clasping dogbane (Apocynum sibiricum). Pale Indian-plantain (Arnoglossum atriplicifolium) and prairie blazing star (Liatris pycnostachya) were just on the brink of blooming, with flower buds present but not yet opened.

Lastly I just want to thank the Friends of the Arboretum (FOA) for funding these free to the public walks every Sunday! If any of you are interested in becoming a member of the FOA, please visit their membership page or call (608) 263-7760.

—Lisa Andrewski

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