About a dozen of us braved the 90-some-degree heat of this late summer Sunday to meander through Curtis Prairie identifying plants and insects, hoping to spot migrant bird travelers passing through, and getting some much needed exercise after being cooped up all week in our air conditioned homes. For much of our walk a pleasant summer breeze was present, taking the edge off the humid afternoon.
It is prime time in Wisconsin to take on the tricky task of identifying plants in the Asteraceae family. From thistles to goldenrods to a wide assortment of plants resembling daisies, just to name a few, this is a large family with more than 23,600 species! We spent much of our time on this walk looking at the differences that characterize these flowering plants. For example, the backs of the leaves on the native prairie thistle or pasture thistle (Cirsium discolor) are white, which is not the case for the invasive bull thistle. Or, New England aster (Symphyotrichum novae-angliae) and silky aster (Symphyotrichum sericeum) and smooth aster (Symphyotrichum laeve) are all a shade of purple and can be found in Curtis Prairie, but a closer examination yields distinguishable differences. The stems and leaves of the New England aster are hairy to the touch, while smooth aster is true to its name with hairless stem and leaves, and the silky aster leaves look very different from both. A quick look at field guide pictures help to verify these characteristics, and we definitely did consult a field guide several times along the way. (The Arboretum Bookstore in the Visitor Center has a nice selection of field guides if you are in the market for a useful tool to carry on your botanical strolls.)
It is also the right time of year to observe flowering gentians in the prairie. We observed both bottle gentian (Gentiana andrewsii) and cream gentian (Gentiana alba) in bloom this afternoon. We also found one blooming Great Plains lady’s-tress orchid (Spiranthes magnicamporum).
We took time to observe the bumble bees hard at work, harvesting nectar from the giant flowering pasture thistles, and tried our luck at identifying the species we saw. The Arboretum is home to at least nine species of native bumble bees, including the rare rusty-patched bumble bee (Bombus affinis). Other insects that caught our attention were monarch butterflies, as well as small milkweed bugs (Lygaeus kalmii), another orange-and-black species that also dines on milkweed plants. Someone in our group pointed out that this insect resembles the box elder bug, and that is true. This time of year the milkweeds are done flowering and many have large seed-filled pods. On these pods we were able to observe this insect at various stages in its life cycle.