ARBORETUM NEWS (NATURALISTSNOTES)

A Prairie Birthday

SUNDAY, JULY 24, 2011

Our scheduled walk was in Curtis Prairie. With temperatures in the 90’s, strong sunshine and high humidity, we headed for the outer edges of the prairie to get as much shade as we could. We started out under a few black cherry (Prunus serotina) trees between the main parking lot and the prairie. There were only three green (unripe) cherries visible to us. True to its name, the berries of the wild black cherry are dark, almost black when they are ripe. They aren’t as sweet as the cultivars we are used to eating, but the wild black cherries are edible and are eaten by a variety of common birds and other mammals. As we entered into the prairie by way of Margaret’s Council Ring, the sunshine showed off the bloom of a dense mix of the yellow ray flowers and the chocolaty brown center of black eyed susans (Rudbeckia hirta), the unusual purplish-blue flowers of bee balm (Monarda fistulosa), and the tiny white flowers of flowering spurge (Euphorbia corollata).

Our next spot of shade we headed for was the oak savanna portion on the north end of Curtis Prairie. Along with more bee balm and a wide, dense stand of smooth sumac (Rhus glabra), we noticed the tiny unripe berries and numerous vines of wild grape. One thing we were expecting but didn’t notice on the grape leaves were Japanese beetles (Popillia japonica). The spark for this discussion was that we noticed in our backyards what seemed to be a preference that the Japanese beetles had for grape leaves. As we got further along in the walk we did notice a few beetles on a variety of plants. It wasn’t until the very end of our walk, as we walked along the south edge of the Native Plant Garden that we noticed what a hungry community of Japanese beetles are capable of – the familiar thorough devouring of a large number of leaves down to a fine laced skeleton of their former selves. This was on two tall bushy shrubs – American hazelnuts (Corylus americana). If you do any gardening or walking in natural areas, you have probably seen this beetle. It is a little more than a half inch long and is an iridescent copper and green color. It is not very destructive in Japan, where it is controlled by natural predators, but in America it is a serious pest of no less than 200 species of plants, including rose bushes, grapes, hops, canna, crape myrtles, and others. Sure enough, when we got back to the Visitor Center, and everyone there had a story of a type of plant in their yard the Japanese beetles sought out and devoured. Some common, but not entirely effective, ways of mitigating the possible destruction that these beetles can cause is the use of insecticidal oils on leaves, systemic insecticides that can alter the odor a plant gives off, or physically knocking the beetles into a soapy water bucket and suffocating them. They are capable of flying away, but if gently given a shove, they seem to prefer a free fall to the ground (unsuspecting of your soapy water bucket).

On the sunnier side, although purple coneflowers, some asters and liatris family plants are on the preferred dining list for Japanese beetles, the sparse stands of purple coneflower (Echinacea pupurea) and pale purple coneflower (Echinacea pallida) in the prairie, and the liatris in the Native Plant Garden – gayfeather (Liatris pycnostachya) were all full of healthy undigested leaves. And, like the other plants on the prairie, they are well adapted to many extremes of our climate, including the dryness and super hot and humid weather we have been experiencing. We also saw stands of a few plants in the middle of the prairie with some distinctive, less typical flowers – pale Indian plantain (Arnoglossum atriplicifolium), a tall plant of four to six feet or more with clusters of small pale yellowish-white flowers and rattlesnake master (Eryngium yuccifolium), a plant with long lance shaped leaves that are not yucca leaves, but do look like them. This plant has a very tiny white flowers also. They are packed into a tough prickly ball of not individually conspicuous flowers – these tightly packed balls of flowers are about the size and shape of a large gumball. In the wetter areas of the prairie were some colorful stands of another plant with a very distinctive flower – swamp milkweed (Asclepias incarnata). Like the other milkweeds it has a dense head of small flowers that all have five scoop shaped petals. The swamp milkweed flowers are a rich, bright purplish-pink. Blooming soon will be the Silphiums. We saw a just the first few compass plants (Silphium laciniatum), prairie docs (Silpium terabinthinaceum) and rosinweeds (Silphium integrifolium) in bloom. All are relatively tall plants with thick, coarse hairy leaves in a variety of shapes and bright yellow ray flowers.

Aldo Leopold wrote a sort of eulogy to Silphiums, in particular the compass plant, in the book, A Sand County Almanac. He wrote that he would “watch eagerly a certain country graveyard” for the first bloom of the compass plant, which he observed on July 24. He noted that few of us, even students of botany would learn what silphiums were, and that as few grieved at the passing of the prairies and the buffalo herds that grazed on the grasses and the other plants such as Silphiums, few would grieve or recognize the passing of the silphium plants. With much to be concerned about in our environment, I like to ponder the look on Leopold’s face as he came upon the bloom of silphiums on Curtis Prairie. And, it is becoming more and more common to find these plants on other prairies, natural areas, and even home plantings. So, we have found value and kept some small spaces for silphiums in our fragmented landscapes. Whatever the weather brings, you can see the silphiums for yourself in bloom (with many others) out on the prairie in the next few months. Check out photos of the flowers in our photo albums
http://uwarboretum.org/photos/album.php?id=49

Paul Borowsky
Naturalist

Located between Lake Wingra and the West Beltline Highway at 1207 Seminole Highway, the University of Wisconsin-Madison Arboretum features the restored prairies, forests and wetlands of pre-settlement Wisconsin. This 1,260-acre arboretum also houses flowering trees, shrubs and a world-famous lilac collection. Educational tours for groups and the general public, science and nature-based classes for all ages and abilities, and a wide variety of volunteer opportunities for groups, families and individuals are available.