ARBORETUM NEWS (NATURALISTSNOTES)

Fall Flowers in the Grady Tract

SUNDAY, SEPTEMBER 16, 2012

The weather smiled on us for Sunday’s tour at the Grady Tract. It’s rare for us to tour at Grady two weeks in a row, but it did happen this time around, confusing one or two of our “regulars”.

A couple of visitors asked about the new gateway to the Grady Tract, having read about it in an Arboretum publication. Although I have heard about this entrance – at the far southeast corner – I have not seen it yet. Time does not allow hiking that far in a tour of standard length. Or perhaps I should say, does not allow hiking that far unless one strides with singular purpose and does not stop to examine any plants, birds, insects, or animal sign?

No such striders were we! We passed blooming white snakeroot, and multitudes of fruit-laden pokeweed, on our way through the Kettle Hole Forest. The woodland is named for its most prominent geological feature – a glacial kettle hole, formed some 12,000 years ago when a large piece of ice broke off under the last of our area’s glaciers. After the glacier retreated, the buried chunk eventually melted, causing earth to collapse and a steep-sided hole to form.

Near the U3 trail intersection – commonly called the “Four Corners” – we paused to get further acquainted with a Ponderosa pine. Not native to Wisconsin, this tree was planted as part of a proposed conifer collection in the early years of the Arboretum’s existence. One of its distinguishing features are its prickly cones – if you roll a Ponderosa cone between your two hands, you will feel the tiny, sharp spike on the tip of each scale. I picked up a couple of cones from the ground so my visitors could appreciate this experience.

Wormwood and white sage are prominent on the West Grady Knoll right now. These two plants are both in the genus Artemisia, but they don’t look anything alike – wormwood (A. campestris) has smooth reddish stems, very fine, whorled leaves, and many round greenish florets in a long, narrow, upright flowerhead. It is not aromatic.

White Sage

White sage, on the other hand (A. ludoviciana) looks just the way you’d expect sage to look – on the woolly side, withgrayish-white, lance-shaped leaves. They are pungent when crushed.

The other delight on the West Knoll at this time of year is hairy grama grass, Bouteloua One nickname I have heard for this plant is “moustache grass”, but if I were doing the naming I would call it “eyelash grass”, or perhaps even “false-eyelash grass”. Its florets or spikelets fall in two dense, slightly curving rows along one side of the stem, right at the stem’s far end, and look just like downcast lashes. Hairy grama grass is low-growing, but very noticeable at trailside on the knoll.

Several different milkweeds can be spotted at this time of year – none of them in flower. Whorled, common, and butterfly milkweed are all present in the sunny areas of the Grady Tract. Whorled milkweed has very fine leaves; butterfly milkweed’s leaves are medium width; and common has very wide, oval-shaped leaves. You may see seed pods on any of them – whorled and butterfly’s pods are narrow, pointed, and stand upright, while common’s are pear-shaped and rough-textured, with a tendency to hang downward. All of them contain seeds which will soon sail off on silken parachutes, hoping to germinate and grow far away from their parents.

What’s in bloom in September? Well, lots of goldenrod, for one thing. There are 20-some species of goldenrod native to Wisconsin; we have 13 of them in the Arboretum. Most obvious right now are Canada, showy, old-field, and perhaps Missouri. I have not seen much Riddell’s goldenrod this season, with its interesting folded leaves. And I think stiff goldenrod has mostly finished its flowering for this year.

Asters are coming into their glory. Of the colorful types, we saw at least sky-blue, aromatic, and New England on our Grady tour. And then there are the “confusing white asters”: heath aster has begun to bloom, but calico, frost, and panicled are present as well. The only two of those I can be absolutely sure of are heath and frost – the former for its very small, tough leaves and dense, almost triangular flowerheads, and the latter because its involucres (the green “baskets” below the flowers) are distinctively bell-shaped.

There is a reason we are so befuddled. I give you a direct quote from Prairie Plants of the UW-Madison Arboretum, by Ted Cochrane: “Calico aster … is particularly complicated, consisting of 3 poorly-defined varieties and hybridizing in Wisconsin with 8 other species.” Or how about this? “The genus contains a multitude of species that can be difficult to distinguish … may hybridize and intergrade.” This, from the man who retired a couple of years ago as curator at the UW’s Herbarium! Kind of gives new meaning to the term “species epithet”, don’t you think?

At the approach to Greene Prairie on Sunday, we spotted turtlehead (Chelone glabra). This is a plant that prefers wetter areas. Similarly to gentians, turtlehead’s flowers are closed, or nearly so; pollinating bees must squeeze inside, and only the long-tongued ones will reach the plant’s nectar.

rattlesnake root

In the prairie itself, we found glaucous white lettuce (which is actually pale purplish-pink, don’t ask). Also known as rattlesnake-root, Prenanthes alba is conspicuously fuzzy. It was a stumper for me on a tour in the Greene several years ago, but I think I will not forget its name again.

Gentians – bottle and fringed – were in evidence. Their vivid blue-violet color is unmatched, in my book. Tip: bottle gentians can also be seen near Margaret’s Council Ring, just off the main Arboretum parking lot.

fringe gentian

But my September favorite is … ta dah … lady’s tresses (Spiranthes magnicamporum). This delicate orchid blooms just as summer gives way to fall; it is a shy little thing, perhaps 7 inches in height. The tiny white flowers spiral around the slender stem; by the time the plant is in bloom, no leaves are in evidence. We found just one

Lady’s tresses

specimen; I’m sure they’ve been more numerous other years. Maybe the drought has had something to do with that?

Prairie dock leaves “waved” to us in the breeze as we navigated the Greene Prairie trail. Silphium terebinthinaceum is finished blooming now, but its stems still stand tall with their maturing seedheads. It had a very, very good flowering year in 2012, unlike last year, when the leaves were everywhere but flower stalks were hard to find.

My last little trail trick, before we headed back upland to finish the tour, was to open a few Baptisia (indigo) seed pods looking for weevils. Apion rostrum is an insect which is dependent on the indigo plant. Early on in the summer, an adult female weevil bores a hole in a fresh, green seed pod with her snoutlike head; she then lays an egg, and pushes it in through the hole. The pod heals up, sealing the egg inside. A larva hatches out, then matures, eating some (but not all) of the seeds in the pod, safe in its womblike enclosure. By late summer, if you crack open a pod, chances are about 1 in 3 that you will find a small dark insect therein. (I don’t feel too badly about exposing them … the pods have started to crack open naturally by now, so the critters would be out on their own very soon anyway.) Sure enough, we met a weevil!

Enjoy September’s treats, at the Arboretum and elsewhere.
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.