Plants & Vegetation
Rare and Interesting Species

Pleasant Valley Conservancy has quite a diverse plant flora. Most of the species were already present when restoration work began, but were often present only in small numbers, hidden beneath the shrubs, or carrying on in a vegetative (nonflowering) state. Some others were introduced during seeding newly cleared areas. All of the introduced species were ones that "belong" in an oak savanna and the seed sources were all local genotypes.

Floristic Quality Index

Botanists and plant ecologists sometimes use a quantitative measure called the Floristic Quality Index (FQI) to express the "quality" of a natural area. This standardized tool, introduced by Floyd Swink and Gerald Wilhelm of the Morton Arboretum, replaces subjective assessments, and although approximate, provides a useful number for comparing various natural areas. FQI is not a stand-alone value, but is used together with other assessments to evaluate the quality of a site.

Coefficient of Conservatism The basis of the FQI calculation is the coefficient of conservatism (C), a value given to each species on a state-wide basis. Each native species is assigned a value from 0 to 10, depending on how widespread or restricted its distribution in the state. Thus, a widespread species such as Canada goldenrod (Solidago canadensis), found in numerous habitats from roadsides to remnant prairies, is assigned a value of 1 whereas prairie dropseed (Sporobolus heterolepis), found almost exclusively on high-quality remnant prairies, has a value of 10.

The C values for northern Illinois are given in the important book by Swink and Wilhelm Plants of the Chicago Area (published by the Indiana Academy of Sciences). A similar set of C values has been established for all members of the Wisconsin flora, and has been published by the Wisconsin Department of Natural Areas. (The C value for each native species is also given on the University of Wisconsin-Madison Herbarium web site.)

The mean C for Pleasant Valley Conservancy was calculated from a detailed check list which combines all our observations for the 4 years 2002 through 2005. This check list has a total of 322 native species (out of a total of 401 identified species), found in the various habitats (oak woods, oak savanna, marsh, prairie remnant, etc.).

Some examples of species at Pleasant Valley with high C values are: Lithospermum canescens (hoary puccoon), Panicum leibergii (prairie panic grass), and Sporobolus heterolepis (prairie dropseed), C=10; Asclepias purpurascens, Asclepias viridiflora, Ceanothus americanus, Cypripedium parviflorus, Eupatorium sessilifolium, and Viola pedatifida, C=9, Aster sericeus, Baptisia lactea, Bromus kalmii, Hasteola suaveolens, Lithospermum incisum, Oxalis violacea, and Pedicularis lanceolata, C=8. In total, there are 190 species at Pleasant Valley Conservancy which have C values of 5 or higher.

The mean coefficient of conservatism for Pleasant Valley Conservancy is 5.1, which is an impressively high for a landscape that has been under restoration for less than 10 years. Using these data, the Floristic Quality Index calculated using the Swink and Wilhelm formula, is 91.3, again, an impressively high number. (According to an assessment by Michigan workers, an FQI greater than 50 represents an area of high conservatism and an area with an FQI greater than 35 is considered floristically important in the state.)

There are many more analyses that can be run, and a number of interesting uses for these calculations. We will be using these calculations to aid us in evaluating our restoration efforts.

Obviously, a high FQI depends on the presence of species with high C values. Such plants show strong fidelity to specific habitats. Such fidelity goes hand-in-hand with rarity. However, a high C value does not necessarily mean that the species is "endangered" or "threatened". This depends on the commoness of the required habitat of a plant with high C value. For instance, Lithospermum canescens has a C value of 10 but is not endangered or threatened, because its preferred habitat, dry prairie remnants, is fairly common in the state.

Our complete list of C values for Pleasant Valley Conservancy plants is available in a Microsoft Excel spreadsheet and will be sent as an email attachment to anyone interested. Send an inquiry to info-tATsavannaoak.org (change the letters AT to a symbol).


Some Interesting Species at Pleasant Valley Conservancy
A few species present were relatively uncommon in our area and were a surprise because they only appeared after restoration began. Among these is the one endangered species on the Conservancy, purple milkweed. Some of the species listed below are not especially rare, but are attractive or interesting.

Purple Milkweed. Purple milkweed (Asclepias purpurascens), a characteristic species of oak savannas, is a state endangered species. It was undoubtedly present at Pleasant Valley Conservancy but it only appeared after clearing and burning in the savanna.

We first observed purple milkweed in the west part of the White Oak Savanna (unit 12B) in 1998. Part of that unit had been cleared in the winter of 1997-1998 and was burned in April of 1998. In June, we were planning management activities with plant ecologist Paul West when we saw this plant in flower. At that time, there were two clusters of flowering plants. The following year several more flowering clusters appeared. Also, we found several clusters that could be clearly identified from the leaves but did not flower. There was no seed set until 2001, when a single cluster produced five pods with seeds. Seeds from these pods were viable and a number of plants were raised, which have been planted in other savanna areas.

In 2001 another savanna area, unit 19, was cleared and burned. In that savanna, two clusters of flowering purple milkweed plants were seen in June 2002. There was no seed set from any of the plants in 2002 or 2003.

Associates of Pleasant Valley Conservancy have been asked to note any occurrences of purple milkweed on the property. The year 2004 had good rainfall in May and June, when the milkweeds are growing their fastest. Perhaps because of these favorable conditions, several new locations were discovered. In order to better understand the biology of this important species, a monitoring program was set up. Each milkweed stand was marked with a permanent metal marker, and its location recorded. Five separate locations are now known, three in white oak savannas and two in bur oak savannas. At three of these sites, seed set occurred in 2004, the first time since 2001. Past experience showed that purple milkweed seeds germinate well and healthy plants can be obtained. We will continue to pursue work on this interesting species.

According to the U.S. Department of Agriculture plant database, purple milkweed is endangered in Wisconsin, threatened in Massachusetts, and of special concern in Tennessee and Connecticut. In Rhode Island it is listed as "historical." The distribution in Wisconsin is shown on the map, taken from the University of Wisconsin-Madison Herbarium web site. The dots on this map represent the locations of collections that have been deposited in the herbarium. According to the Atlas of Wisconsin Prairie and Oak Savanna (Cochrane, Theodore and Iltis, Hugh, 2000): "Purple milkweed favors mesic prairies and edges of open woodlands and brushy roadbanks that simulate original savanna borders and prairie thickets."

  

Glade Mallow. Glade mallow (Napaea dioica), a handsome plant of wet prairies and marshes, is the only plant endemic to the north-central United States. On the state species list for Wisconsin, it is listed as of "special concern." Even in the states where it is found, it is rare or threatened. In Wisconsin it is found only in counties in western and southern Wisconsin. Despite this rarity, it is relatively common in our part of Dane County. U.S. Highway 14 between the villages of Cross Plains and Black Earth has a lot of glade mallow (unfortunately, mixed with wild parsnip and sweet clover!).

 

Glade mallow is a relative of hibiscus, and because of its tall size and large flower heads, it is often grown in gardens.

At Pleasant Valley Conservancy glade mallow was found originally only at the edge of the marsh at the corner of Pleasant Valley Road and County Highway F. Seeds have been distributed elsewhere in the edges of our wetland and this plant is now spreading. In 2004 we had good seed set in the planted corn field near the barn which we call the "Barn Prairie."

Eupatorium sessilifolium. In Wisconsin this savanna species is designated as "special concern." We have only a small population, which was present when restoration began. We are working to establish this species at other locations on the Conservancy. In 2006 we raised a few plants from seed and transplanted them to suitable locations. One of these transplants grew well and went on to flower and set seed its first summer. This result encourages us to do more transplants in future years.

Yellow Giant Hyssop. Yellow giant hyssop (Agastache nepetoides) is another savanna plant which is restricted in its distribution. In Wisconsin it is classified as "threatened." The University of Wisconsin-Madison Herbarium has collections from only a few counties in southern Wisconsin. In addition to Wisconsin, it is considered "threatened" in New York and Vermont and of "special concern" in Connecticut.

Yellow giant hyssop was apparently not present at Pleasant Valley Conservancy before restoration began. We introduced it to areas that we had begun to restore from seed collected at another site in Dane County. It has done quite well and has spread on its own. It is now found in the bur oak savanna at the top of the ridge, as well as below the ridge top on the south slope (units 2, 3, 4, 5, 6, 8, 9, 10, 11, and 19). We are using seeds collected from several of these populations to seed newly cleared savanna areas.

Bottle Brush Grass. Bottle brush grass (Elymus hystrix) is one of our native savanna grasses. Originally, we had only a small patch of this grass on one of our remnants. However, there was a large amount of this grass about a mile away on Blue Mounds Trail. We collected seeds from both sites and used them to seed our newly cleared savanna. This grass has become established well and is now widespread in both the bur oak and white oak savannas. It is a tall grass, quite characteristic in its form, and hence easy to identify. Although not especially rare in Wisconsin, it provides a charming accent to the savanna flora.

Large Yellow Lady Slipper. The large yellow lady slipper (Cypripedium parviflorum var. pubescens) is one of our most handsome orchids. We find it primarily in the oak woods on the north-facing hillside, where it is locally common. It responded well there to a controlled burn carried out in October 1999. It has also sprung up in the bur oak savanna after it was cleared and burned. (see photo).

 

Wild Indigo. Wild indigo (Baptisia alba) is a large showy plant that is widely used in prairie restorations. At Pleasant Valley Conservancy we have a fairly substantial native population that has an interesting history. This population was present on the north (wetter) side of our upper CRP field (Toby's Prairie) but it had never been especially showy or noticeable. It survived two treatments with glyphosate that were used in preparation for prairie planting. Two years later, after the prairie plants had started to grow and we had carried out controlled burns, wild indigo plants became well established at the north end of the field. Flowering and seed set have been excellent and we have collected seed for other plantings in subsequent years. It is now established in the Pocket and Valley Prairie as well.

Kalm's (Prairie) Brome. Kalm's or prairie brome (Bromus kalmii) is the most common native brome in Wisconsin. It should not be confused with smooth brome (Bromus inermis), a farmyard brome that was introduced from Europe. (Although common in Wisconsin, Kalm's brome is "endangered" in New Hampshire and Maryland and possibly extirpated from Maine.)

In Wisconsin Kalm's brome is most commonly found along borders and clearings and along roadsides in dry to mesic sites. Our remnant population was at the base of the goat prairie (unit 1) where it was growing in soil formed on the Tunnel City Sandstone. We collected seed from that location and used it in our prairie restorations in 1998 and 1999, as well as on the remnants on the south slope that were cleared in 1998-2000. It has done well at both the planted prairies and the remnants, and is now fairly widespread at Pleasant Valley Conservancy. We have collected seed from the planted prairies for the seed mix we are using in the more open parts of our savanna restorations.

Showy goldenrod. In its 140 acres, Pleasant Valley Conservancy had a number of tiny prairie remnants that had escaped the plow and had not become brushed in. One of them was a small parcel, about 20 X 50 feet in size, between a ravine and the upper plowed field. (We called this parcel Toby's Annex, because it was an addendum to the agricultural field we planted and called Toby's Prairie.) Toby's Annex was apparently not plowed because it was slightly downhill and a plow could get stuck there in wet weather. Several kinds of prairie plants were present in Toby's Annex, including round-headed bush clover, gray goldenrod, flowering spurge, yellow coneflower, Illinois trefoil, purple Joe Pye weed, black-eyed susan, wild bergamot, and prairie cinquefoil. Also present was a nice stand of the native shrub American hazelnut (Corylus americana).

One of the most handsome prairie plants in this remnant is showy goldenrod (Solidago speciosa). When we were planning to treat the field with glyphosate in preparation for prairie planting, we staked off this area so that the contractor doing the herbicide spraying avoided it. It became the principal source of showy goldenrod seed for planting other prairies.
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