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1995 Midwest Oak Savanna and Woodland Ecosystems Conferences


Appendix D

The following lists of indicator plant species is an example of efforts to aid in the identification of remnants of oak savannas and oak woodlands. Such lists help provide "search images" for highly restorable remnants. Biologists in other eco-regions should consider publishing locally appropriate lists.


by Brian W. Pruka1

Several Wisconsin botanists have developed a list of indicator species to help restorationists identify savanna (10-50 percent canopy) and open oak woodland (50-80 percent canopy) remnants. I and my colleagues--Brian Bader, Ted Cochrane, Eric Epstein, Rich Henderson, Randy Hoffman, and Mark Leach--believe that the presence of these light-dependent understory species indicates a recent closure of the canopy. Wooded sites containing sufficient populations of these species, therefore, have the highest potential for recovery if properly managed through the use of prescribed burns, mechanical canopy thinning, and other techniques.

This list, although preliminary, should be useful to restorationists in southern Wisconsin, and in the neighboring regions of southeastern Minnesota, northeastern Iowa and northern Illinois. I anticipate that we will refine it to provide separate indicator species lists for oak openings, oak barrens, and open oak woodlands. For now, it should serve field investigators who are attempting to identify and assess remnant sites for their restoration potential.

This list consists of four categories of identification.

Category 1 species are the best indicators of former savannas and open woodlands because they tend to be limited to partial canopy conditions. In more densely-wooded sites, these species are usually in a state of declining vigor due to the ever-increasing canopy closure. They typically persist in densely-wooded sites only near canopy openings such as woodlot edges, roadsides, or brushed utility corridors.

Category 2 species are moderate indicators of former savannas and/or open woodlands. Commonly found under partial canopies, they are also important parts of either prairies or forests, being more common in those communities than category 1 species.

Category 3 species are marginal indicators of former savannas and/or woodlands. They tend to have broad habitat amplitudes that allow them to grow in several upland plant communities.

Category 4 species are tentatively proposed as indicators of former savannas and/or open woodlands. Due to our lack of sufficient experience with these species, we chose to list them in a separate category. Further field investigations should help place these species in one of the other categories. 

Category 1 Species--Best Indicators

Agastache nepetoides

Yellow giant hyssop

Agastache scrophularieaefolia

Purple giant hyssop

Anemone virginiana

Tall anemone

Asclepias purpurascens

Purple milkweed

Aster linariifolias

Flax-leaved aster

Astragalus canadensis

Canadian milkvetch

Aureolaria grandiflora

Yellow false foxglove

Aureolaria pedicularia

Clammy false foxglove

Baptisia leucantha

White wild indigo

Baptisia leucophaea

Cream wild indigo

Besseya bullii

Kitten tails

Blephilia ciliata

Ohio horse-mint

Bromus kalmii

Prairie brome

Cacalia atriplicifolia

Pale Indian plantain

Cacalia muhlenbergii

Great Indian plantain

Camassia scilloides

Wild hyacinth

Castilleja occinea

Indian paintbrush

Ceanothus americana

New Jersey tea

Ceanothus ovatus

Prairie redroot

Cirsium altissimum

Woodland thistle

Convolvulus spithamaeus

Low bindweed

Cypripedium pubescens

Large yellow lady-slipper

Desmodium canadense

Showy tick-trefoil

Dodecatheon meadia

Shooting star

Elymus villosus

Silky wild rye

Elymus virginicus 

Virginia wild rye

Erigeron pulchellus

Robin's plantain

Eupatorium sessilifolium

Woodland boneset

Gentiana alba

Cream gentian

Heuchera americana

Prairie alum-root

Hieracium candense

Canada hawkweed

Hypoxis hirsuta

Yellow star-grass

Krigia biflora

False dandelion

Lilium philadelphicum

Prairie lily

Lysimachia lanceolata

Lance-leaved loosestrife

Lysimachia quadrifolia

Whorled loosestrife

Oenothera perennis

Small sundrops

Oxalis violacea

Violet wood-sorrel

Pedicularis canadensis

Wood betony

Penstemon gracilis

Slender beard-tongue

Phlox pilosa

Prairie phlox

Polemonium reptans

Jacob's ladder

Polygala senega

Seneca snakeroot

Polytaenia nutallii

Prairie parsley

Prenanthes alba

Lion's foot

Ranunculus fascicularis

Early buttercup

Ranunculus rhomboideus

Prairie buttercup

Silene stellata

Starry campion

Solidago hispida

Hairy goldenrod

Taenidia integerrima

Yellow pimpernel

Tephrosia virginiana

Goat's rue

Thaspium trifoliatum

Meadow parsnip

Tomanthera auriculata

Eared false foxglove

Triosteum aurantiacum

Late horse gentian

Triosteum perfoliatum

Early horse gentian

Veronicastrum virginicum

Culver's root

Zigadenus elegans

White camas

Zizia aurea

Golden Alexander

Category 2 Species--Moderate Indicators

Category 3 Species--Associate Spp./Weak Indicators

Actaea pachypoda

White baneberry

Agrimonia gryposepala

Tall agrimony

Agropyron trachycaulum

Slender wheatgrass

Amphicarpa bracteata

Hog peanut

Apocynum androsaemifolium

Spreading dogbane

Apocynum cannabinum 

Indian hemp

Brachyelytrum erectum

Long-awned wood grass

Galium concinnum

Shining bedstraw

Helianthus hirsutus

Oblong sunflower

Hieracium longipilum

Hairy hawkweed

Koeleria cristata

June grass

Kuhnia eupatorioides

False boneset

Lathyrus ochroleucus

Pale pea

Lechea intermedia 

Intermediate pinweed

Lechea tenuifolia

Slender-leaved pinweed

Liatris aspera 

Rough blazing star

Liatris pychnostachya

Prairie blazing star

Lysimachia quadriflora

Narrow-leaved loosestrife

Oryzopis racemosa

Black-seeded ricegrass

Panicum oligosanthes var. scribnerianum

Few-flowered panic-grass

Panicum lanuginosum var. implicatum

Hairy panic-grass

Petalostemum purpureum

Purple prairie clover

Polygala sanguinea

Field milkwort

Ratibida pinnata

Yellow coneflower

Rudbeckia hirta

Black-eyed Susan

Sisyrinchium campestre

Prairie blue-eyed grass

Smilacina stellata

Starry false Solomon's seal

Solidago juncea

Early goldenrod

Solidago rigida

Stiff goldenrod

Solidago ulmifolia

Elm-leaved golden rod

Tradescantia ohiensis

Common spiderwort

Uvularia grandiflora


Viola pedata

Bird's foot violet

Category 4 Species--Proposed Indicators

Agrostis perennans

Autumn bentgrass

Asplenium platyneuron

Ebony spleenwort

Bromus purgans

Woodland brome

Carex rugosperma

a sedge

Corallorhiza odontorhiza

Late coral-root

Desmodium canescens

a tick-trefoil

Helianthus decapetalus

Pale sunflower

Lactuca floridana

Woodland blue lettuce

Lactuca ludoviciana

Western prairie lettuce

Lespedeza violacea

Violet bush clover

Polygala verticillata

Whorled milkwort

Silene antirrhina

Sleepy catchfly

Symphoricarpos occidentalis


Trillium recurvatum

Red trillium

Vicia americana

American vetch

Vicia caroliniana

Wood vetch

1 Adapted from Pruka (1995) with permission of author and Restoration & Management Notes.  


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