ARBORETUM NEWS (NATURALISTSNOTES)

Spring on the Grady Tract Savanna and Greene Prairie

SUNDAY, MAY 18, 2014

It was a sunny, inviting spring day to take a walk through the Grady Tract. We started out by discussing and identifying several of the more pernicious invasive species of the unit, namely buckthorn, honeysuckle and oriental bittersweet. Over the last year, control efforts have involved a blend of multiple restoration techniques matched with well-chosen timing. We stopped at an oak grove just south of the Kettle Hole Forest to witness the result of these efforts; a withering mass of oriental bittersweet that had begun to wrap around the oaks and shade out the canopy. The native American bittersweet (Celastrus scandens) flowers and fruits at the terminal end of the vine only, whereas the invasive bittersweet (Celastrus orbiculatus) holds fruit on various nodes along the vine. Well-informed environmental citizens can help to reduce the spread of the invasive bittersweet by knowing how to identify them and requesting that commercial growers carry only the American species.

Now onto the fun part of the tour—the native plants! The sandy soils of West Grady Knoll hosts a surprisingly diverse plant community, even early in the growing season. Plants in bloom included pussytoes (Antennaria sp.), wood sorrel (Oxalis violaceae), rock cress (Arabis sp.), starry Solomon’s seal (Maianthemum stellatum) and both the bird’s foot violet (Viola pedata) and prairie violet (V. pedatifida); the former with an orange center in the flower, while the later has bearded petals. The hoary puccoon (Lithospermum canescens) was playing coy and on the verge of blooming. Alas, we missed them today, but they should be brilliant by mid-week.

As we walked along the savanna edge toward Greene Prairie, it was evident that a prescribed burn had been conducted in the wooded section within the last month or so. Plants were beginning to spring up (no pun intended), including a patch of Convallaria majalis (Lily-of-the-valley), an escaped, ecologically invasive species. As Aristotle said, nature abhors a vacuum. Although not an ideal filler, for some reason I am less antagonistic towards this plant than other non-natives.

May is a great time of the year to find the short-stature plants of Greene Prairie; golden alexanders (Zizia aurea), heart-leaved golden alexanders (Z. aptera), prairie alum root (Heuchera richardsonii), and star or bastard toadflax (Comandra umbellata). Star toadflax is commonly associated with high quality natural areas and serves as a pollinator resource for our early native bees and flies. It is also one of the few prairie plants to produce a fruit; a quite small drupe, but undeniably a fruit, and supplies a popular treat for birds and rodents. Several hemi-parasitic species were also present, the wood betony (Pedicularis canadensis) and saxifrage. Last, but certainly not least, was the Houstonia caerulea or azure bluet. This lovely, delicate plant is classified as a species of special concern, being known to grow in only a handful of counties in southern Wisconsin. Considering the status, this particular grouping was no ‘shrinking violet’. The solitary clutch of 8-10 flowers was boldly growing right along the edge of the prairie trail. The privilege of seeing this rare plant was a nice way to close out the tour.
—Amy Jo Dusick, May 18, 2014

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.