ARBORETUM NEWS (NATURALISTSNOTES)

Greene Prairie and the Grady Knolls Tour – Naturalists’ Notes

SUNDAY, JULY 27, 2014

The floral treats on the Greene Prairie right now are too numerous to mention. But I will try to hit the highlights.

We caught the briefest sprinkle of rain on Sunday’s tour – 15 minutes before the hike ended. No one seemed to mind at all. Otherwise it was a gorgeous, breezy day.

We’d begun with a greeting by a red-tailed hawk. It was perched in the Evjue Pines, just barely off the parking lot, and was being harassed by a robin and other small birds. Though large, it was not a full adult, since it didn’t yet have the red-orange tail feathers which define the species. It sat silently as the wind ruffled its feathers and the much smaller birds yammered at it, then finally flew off, dare I say with a resigned expression?

We lingered a moment longer to examine nightshade – deadly or not? Don’t eat the berries of this tomato relative!

On the way down through the Kettle Hole Forest we noted the Pokeweed Plantation that flourishes along that trail. See next month’s NewsLeaf (newsletter of the Friends of the Arboretum) for more about that plant.

In fact pokeweed (Phytolacca americana) furnished one of the day’s two Presidential “mentions” – James K. Polk having successfully used it as campaign advertising in 1844. The other was white snakeroot (Ageratina altissima, formerly Eupatorium rugosum), which is coming into bloom. White snakeroot, if eaten by cows, leaves a toxin in the animal’s milk that can be fatal to humans. In fact it was just this “milk sickness” which killed Nancy Hanks Lincoln in 1818, when her son Abraham was but nine years old.

We also examined, at a safe distance, the vine and ground-layer forms of poison ivy (Toxicodendron/Rhus radicans), comparing them to Virginia creeper (Parthenocissus quinquifolia). A visitor asked what family the latter vine is in; I didn’t know “off the cuff”, but I do now: it belongs to the Grape family, Vitaceae.

Flowering spurge is particularly lovely right now on the West Knoll; in fact, Euphorbia corollata’s minute white “flowers” give a calico-fabric look to some sections of that hilltop prairie. Why did I put “flowers” in quotation marks? Because the bright-white structures which look like petals are actually bracts – modified leaves. This geekish factoid helps explain why they last so long – true petals fade (and drop) soon after pollination has been accomplished and seeds begin to form. Bracts are much more persistent. That’s why flowering spurge seems to have such an extended blooming period. If you look closely in another couple of weeks, you will see that a little round green fruit has formed where the yellowish “flower center” used to be, and is held above the still-pristine bracts on a short stem.

Also on the knoll, one sees much wormwood (Artemisia campestris) – an upright plant with red stems, very fine leaves, and profuse, pale green buds. Although these will open soon, the tiny flowers will not be significantly showier than the buds are. At the crest of the hill, look down to see blooming mustache grass, also known as hairy grama grass or Bouteloua hirsuta. This species is one of my summertime favorites!

A humble flower, but worth the trouble to find, is sand evening-primrose (Oenothera clelandii). Its coarser cousin COMMON evening-primrose (O. biennis) may be more familiar. This one has the characteristic 4-parted yellow flowers, but is much smaller in stature and features pointed petals.

We noted a lot of leadplant (Amorpha canescens), past its bloom period but still much in evidence: silvery leaves, upright mostly-faded racemes. For some reason this plant was not as showy this summer as usual.

One thing I did NOT see on the knoll, on my earlier scouting expedition or on the tour proper, was the solitary clasping milkweed (Asclepias amplexicaulis) that has been noted there for many years. I hope that observation, or lack of it, is simply a matter of my not looking in the right place. I would hate to think that this plant has disappeared from our midst.

Eventually, winding our way past the spent purple love-grass (Eragrostis spectabilis) and the sparse Deptford pinks (Dianthus armeria), we entered Henry Greene’s prairie. Escorted by a pair of adult sandhill cranes, among the many floral benefits we enjoyed were winged and narrow-leaved loosestrife (do not fear that name; the purple loosestrife which is a wetland pest is a different critter), white meadowsweet, blazing-star or gayfeather, hedge nettle, Kalm’s St. John’s wort, and Michigan lily.

All right, all right, here are the Latin names for all those plants: Lythrum alatum, Lysimachia quadriflora, Lythrum salicaria, Spiraea alba, Liatris pycnostachya, Stachys palustris, Hypericum kalmianum, and Lilium michiganense respectively.)

And then there were two plant species classified as “threatened” in Wisconsin – one of which is more bountiful this year than I’ve ever seen, and one of which was, well, only ONE. The former is prairie parsley – the more you look, the more you see. It’s in fruit, holding high its umbels of upright, yellowish, developing seeds. This plant’s leaves are finely cut, unlike those of its nasty look-alike, poison/wild parsnip (Pastinaca sativa). See pages 47 and 48 in Ted Cochrane’s book of prairie plants of the Arboretum, if you have it.

The loner, but equally exciting, is prairie Indian-plantain, Arnoglossum plantagineum. Its relative PALE Indian-plantain (A. atriplicifolium) grows in profusion along our McCaffrey Savanna firelane, bearing large deeply-toothed leaves all along its tall stems. The prairie kin has a very similar flowerhead – in fact that’s how my fellow naturalist and I had immediately recognized it as an Indian-plantain – but has a rosette of leaves at ground level, then smaller, oval or egg-shaped ones going up the stalk. The Greene Prairie specimen is well off-trail, but a look with binoculars will reveal the parallel (not networked) venation of those leaves.

By the way yet another Indian-plantain has insinuated itself just outside the Visitor Center’s back door. Look left as you go out – there’s a tall plant featuring whitish flowers and good-sized, arrow-shaped leaves. This is SWEET Indian-plantain, Hasteola suaveolens. (I had to ask Native Plants Gardener Susan Carpenter this plant’s identity again this year … I promise to try really hard to remember it this time.) It’s a volunteer in that location, having planted itself just beyond the end of the downspout. Who knows where it came from?

The tour description, written months ago, had stated “Prairie dock is prolific on the Greene Prairie”. That it is, but it’s not yet in bloom. In fact not a single flower stalk of prairie dock (Silphium terebinthinaceum) or its close relative, compass plant (S. laciniatum), can be seen. Leaves, yes; tall stems or buds, no. Any week now they should be shooting up.

I’m sure I have missed recounting some of our Sunday delights. What a lovely afternoon, spent in charming company.

Kathy Miner, Arboretum 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.