On a warm sunny Sunday afternoon with a pleasant breeze sixteen of us headed into the Grady Tract to explore this south of the beltline section of the UW–Madison Arboretum. Several of today’s visitors were new to the Arb, including a young visitor from Germany, a few were Friends of the Arboretum and best of all, Susan Carpenter joined us! For the few of you who may not know Susan, she is the lady who over the past several years created the native plant gardens around the Arboretum Visitor Garden. She frequently leads both public and private tours in these gardens. She is one of the best plant taxonomists and ecologists or staff here. As one of the regular participants on these Sunday tours said when he saw Susan was along, “well I guess we can leave our Prairie Plant field guides in our cars, with Susan along we have all the information we’d need to identify just about any plant we’d see.” I knew having Susan with us would make my efforts at identifying prairie flowers much easier.
As usual, our first stop still within sight of the entrance gate was to explain the plant community concept that was the overriding idea in the minds of the early Arboretum founders when they set out to establish this unusual Arboretum. We viewed the Evue Forest northern red and white pine plantings as an example of a northern Wisconsin pine forest and went on to consider a variety of different plant communities which have been established here since back in the 1930s. Our first plant in flower was a White Snakeroot (Ageratina altissima), which have been in bloom almost all summer long. We discussed a few plants along the fire lane with very rough seeds that are obviously designed to attach to animal fur or people’s clothing for maximum dispersal. The extensive patch of Pokeweed (Phytolacca Americana) now has attractive deep purple berries on most plants. The visitors were cautioned not to eat any part of this plant as all guide books caution it is poisonous if eaten.
When we got to the old kettle hole, Arnie, one of the Sunday regulars, volunteered to point it out and explain about it. Both Susan and I elaborated more about how a kettle hole results from a large chunk of ice separating from a retreating glacier and then slowly melts down to leave the familiar kettle hole as evidence of the glacier’s retreat.
Heading down the fire lane we soon saw our first prairie or savanna plants as we approached the West Grady Knoll, a goldenrod in full bloom. I knew we would see several different goldenrod species today. I also knew I could probable only positively identify a few of them. To me some goldenrods are almost as hard to positively identify as are some of the very similar asters. Here is where Susan really came in handy! Instead of my suggesting here is another type of goldenrod and then trying to find out which one by looking in my field guide, Susan would tell us which one it was and what the distinguishing feature are. She even elaborated on my brief explanations of what restoration activities had been done to create the West Grady Knoll savanna from the scrub oak forest that used to be here. We explained the importance of fire as a regular management tool to maintain the savanna and pointed out this area had been burned this spring. Even so, you could see way too many woody plants, sumac, aspen and especially young oaks that are on their way to creating an oak forest again.
On the knoll we stopped to enjoy sage-wort (Artemisia campestris), white sage (Artemisia ludoviciana), butterfly-milkweed (Asclepias tuberosa), now with seed pods, a few late evening primrose, and past flowering white and purple prairie clovers, lead plant (Amorpha canescens), flowering spurge (Euphobia corollata). Compared to earlier this summer the knoll has noticeably fewer plants in bloom and many have already developed their seeds.
Moving on to the Greene Prairie, we mentioned Henry Campbell Greene’s substantial role in almost single handedly creating this prairie over about 20 years, from the early 1940’s to the mid 1960’s. As we entered the prairie we found a few tuttleheads (Celone glabra) still in bloom. We also enjoyed the beauty of a few bottle gentians (Gentiana andrewsii).
We noticed the expanse of tall flowering sunflowers. While I was content to point out these plants as members of the genus Helianthus and just refer to them as sunflowers, Susan frequently provided the common name as she explained how to distinguish saw-tooth (Helianthus grosserratus) rough-leaved sunflowers (H. strumosus), stiff sunflower (H. pauciflorus). The frequent goldenrods provide attractive yellow flower clusters at this time towards the end of summer. The familiar Canadian goldenrod (Solidago Canadensis) is the most common one. In addition we identified grass-leaved goldenrod (Euthamia graminifolia), old-field or Dyer’s goldenrod (S. nemoralis), Ridell’s goldenrod (S. riddellii), stiff goldenrod (S.rigida) showy Goldenrod (S. speciosa).
Right along the path in Greene Prairie we found several Lady’s Tresses (Spiranthis magnicamporam) and thanks to Susan, I learned a new aster, flax-leaved aster (Ionactis linariifolia). Other asters in bloom included smooth aster (Symphyotrichum laevis), sky-blue (S. oolentangiense), New England aster (S. novae-anglicae) and shining aster (S. firnum).
Noticeably absent from the usual late August blooming prairie flowers were both compass plant (Silphium laciniatum) and prairie dock (Silphium terebinthinaceum). Although both species are abundant on Greene prairie, as evident by their very visible large leaves, very few of these large silphiums have produced their usually abundant tall flowering stalks. In places where several of these old stalks still remain from last year, no new stalks from this year are visible. This is not the case in other restored prairies in the Madison area, such as the Biocore Prairie near Eagle Heights, which has its normal complement of these two silphiums in flower. Why should these two relatively abundant species not be in flower on Greene Prairie as they usually are? Several various explanations have been suggested, but none really seems to explain this phenomenon. Some have suggested we wait to see if they bloom as usual next year before we ponder too much over their lack of blooming this year. Maybe time will tell.
As we headed out the shorter route we stopped to enjoy a few late liatrus still in bloom. We spotted the lone prairie indian-plantain (Arnoglosson plantaginem), a Wisconsin threatened species, which used to be abundant on this prairie back in the 1960s and since then has only appeared in very low numbers and only during occasional years.
By the time we reached the fire lane we had only about five minutes to get back to the parking lot by the allotted time of 3 pm. We had so enjoyed out tour of the Grady Tract that our two hours had passed quickly. I encouraged our visitors to come again at different times during the summer to experience the prairie with a different complement of flowers in bloom.