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, which represents the probability that this plant species is likely to occur in landscapes relatively unaltered from those of pre-settlement times. Plant species with high C values are relatively specialized in their requirements and thus are found in more restricted habitats.

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 website and in Wildflowers of Wisconsin and the Upper Midwest, by Merel Black and Emmet J. Judziewicz, University of Wisconsin Press, Madison, Wisconsin.

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 319 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 alba, 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 value for a landscape that has been under restoration for such a short period of time. 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.)

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 commonness of the required habitat of a plant with a 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.

Floristic Quality Index for Each Management Unit

Name	FQI	Acreage	Total species	Present status of unit
Unit 6	63	4.48	153	Upper (Bur oak savanna) Lower (Prairie remnant)
Unit 11A	61	5.17	119	Prairie remnant and bur oak savana
Toby’s Prairie	61	3.63	126	Dry-mesic prairie (partially remnant; mostly planted)
Unit 10	60	2.9	136	Bur oak savanna
Unit 12A	59	5.95	138	White oak savanna
Valley Prairie	58	3.85	130	Dry, mesic, and wet-mesic prairie (planted)
Pocket Prairie	57	4.5	104	Dry, mesic, and wet-mesic prairie (planted)
Unit 7	56	1.58	117	Upper (Bur oak savanna) Lower (Prairie remnant)
Unit 3	56	1.03	105	Prairie remnant
Crane Prairie	55	2.6	130	Dry, dry-mesic, and mesic prairie (planted)
Unit 8	54	1.3	102	Bur oak savanna
Unit 12B	54	0.98	114	White oak savanna
Unit 5	52.5	1.61	105	Bur oak savanna
Unit 2	52	1.6	89	Prairie remnant
East Basin	51.5	4.4	100	Dry-mesic, mesic, and wet-mesic prairie (planted)
Ridge Prairie	51	1.67	100	Dry-mesic prairie (planted)
Unit 23	51	0.38	93	Bur oak savanna
Unit 19C	48	1.13	71	Black/bur oak savanna
Unit 21	47	3.38	75	White oak woodland
Triangle	47	0.55	81	Hill’s oak savanna
Unit 20 combined	46	3.35	86	Woods and prairie mix
Barn	46	0.48	87	Wet mesic prairie (planted)
Unit 9	45	1.82	82	Bur oak savanna
Cabin Prairie	45	0.54	83	Mesic prairie (planted)
Unit 1	44	1.18	61	Prairie remnant
Unit 11D	43	4	74	White oak savanna
Unit 4	41	0.32	48	Prairie remnant
Unit 19A	40.8	0.33	69	Bur oak savanna
Unit 19B	38	1.64	51	Bur oak savanna
Unit 19D	35	1.05	30	Bur oak/black oak savanna
Unit 19E	34	1.47	37	White oak savana

The table below lists the species found at Pleasant Valley Conservancy in order of their C value, from high to low, based on data from 4 years.

Coefficient of Conservatism for Plant Species

Latin name	Common name	C value
Carex prairea	Prairie sedge	10
Lithospermum canescens	Hoary puccoon	10
Panicum leibergii	Prairie panic grass	10
Sporobolus heterolepis	Prairie dropseed	10
Asclepias purpurascens	Purple milkweed	9
Asclepias viridiflora	Short green milkweed	9
Aster prenanthoides	Crooked aster	9
Ceanothus americanus	New Jersey tea	9
Cypripedium parviflorum var pubescens	Large yellow lady-slipper	9
Eupatorium sessilifolium	Woodland boneset	9
Liatris cylindracea	Dwarf blazing star	9
Stipa sp	Needle grass	9
Viola pedatifida	Prairie violet	9
Aster sericeus	Silky aster	8
Astragalus canadensis	Canadian milkvetch	8
Aureolaria grandiflora	Yellow false foxglove	8
Baptisia alba	White wild indigo	8
Bromus kalmii	Prairie brome	8
Carex eburnii	Bristle-leaf sedge	8
Cirsium muticum	Swamp thistle	8
Coreopsis palmata	Prairie tickseed	8
Dalea candida	White prairie clover	8
Eryngium yuccifolium	Rattlesnake master	8
Hasteola suaveolens	Sweet Indian plantain	8
Hypoxis hirsuta	Yellow star-grass	8
Lithospermum incisum	Fringed puccoon	8
Oxalis violacea	Violet wood-sorrel	8
Parthenium integrifolium	Wild quinine	8
Pedicularis canadensis	Wood betony	8
Pedicularis lanceolata	Lousewort	8
Pediomelum esculentum	Prairie turnip	8
Polygala senega	Seneca snakeroot	8
Silphium laciniatum	Compass plant	8
Solidago ptarmicoides	Prairie goldenrod	8
Sphenopholis obtusata	Wedge grass	8
Symplocarpus foetidus	Skunk cabbage	8
Viburnum prunifolium	Black haw	8
Actaea rubra	Red baneberry	7
Allium cernuum	Nodding wild onion	7
Amorpha canescens	Lead-plant	7
Arabis canadensis	Sickle pod	7
Aralia racemosa	Spikenard	7
Arenaria stricta	Sandwort	7
Asclepias exaltata	Poke milkweed	7
Bouteloua hirsuta	Hairy gramma grass	7
Bromus ciliatus	Fringed brome	7
Campanula aparinoides	Marsh bellflower	7
Carex grayi	Bur sedge	7
Carex stricta	Tussock sedge	7
Carex trichocarpa	Hairy-fruit sedge	7
Chelone glabra	Turtlehead	7
Cornus rugosa	Round-leaved dogwood	7
Dalea purpureum	Purple prairie clover	7
Desmodium illinoense	Illinois tick-trefoil	7
Dicentra cucullaria	Dutchman’s breeches	7
Dodecatheon meadia	Shooting star	7
Echinacea pallida	Pale purple coneflower	7
Galium lanceolatum	Lance-leaved bedstraw	7
Gentiana alba	Cream gentian	7
Gentianella quinquefolia	Stiff gentian	7
Geum triflorum	Prairie smoke	7
Goodyera pubescens	Rattlesnake plantain	7
Helianthus decapetalus	Pale sunflower	7
Helianthus pauciflorus	Prairie sunflower	7
Heuchera richardsonii	Prairie alum-root	7
Koeleria macrantha	June grass	7
Liatris pycnostachya	Prairie blazing star	7
Linum medium texanum	Small yellow flax	7
Lobelia cardinalis	Cardinal flower	7
Panicum latifolium	Broad-leaved panic-grass	7
Potentilla arguta	Prairie cinquefoil	7
Quercus alba	White oak	7
Saxifraga pensylvanica	Swamp saxifrage	7
Scutellaria parvula	Leonard’s skullcap	7
Silphium terebinthinaceum	Prairie dock	7
Sisyrinchium campestre	Blue-eyed grass	7
Solidago missouriensis	Missouri goldenrod	7
Taenidia integerrima	Yellow pimpernel	7
Thalictrum dioicum	Early meadow-rue	7
Uvularia grandiflora	Bellwort	7
Viburnum acerifolium	Maple-leaved viburnum	7
Viola canadensis	Tall white violet	7
Viola pedata	Bird’s foot violet	7
Zizia aurea	Golden Alexander	7
Actaea alba	White baneberry	6
Amelanchier arborea	Juneberry	6
Anemone cylindrica	Thimbleweed	6
Anemone quinquefolia	Wood anemone	6
Angelica atropurpurea	Great angelica	6
Arabis divaricarpa	Rock cress	6
Aralia nudicaulis	Wild sarsaparilla	6
Asclepias tuberosa	Butterfly weed	6
Aster firmus	Shining aster	6
Aster laevis	Smooth blue aster	6
Aster umbellatus	Flat-top aster	6
Bouteloua curtipendula	Side oats grama	6
Bromus latiglumis	Ear-leaved brome	6
Caltha palustris	Marsh marigold	6
Cardamine bulbosa	Spring cress	6
Carex lacustris	Common lake sedge	6
Cicuta maculata	Water-hemlock	6
Cirsium altissimum	Woodland thistle	6
Coeloglossum viride	Long-bracted green orchid	6
Desmodium glutinosum	Pointed tick-trefoil	6
Elymus hystrix	Bottlebrush grass	6
Elymus riparius	Riverbank wild rye	6
Elymus villosus	Silky wild rye	6
Elymus virginicus	Virginia wild rye	6
Eupatorium perfoliatum	Common boneset	6
Eupatorium purpureum	Purple joe-pye weed	6
Galearis spectabilis	Showy orchis	6
Galium concinnum	Shining bedstraw	6
Gentiana andrewsii	Bottle gentian	6
Helianthemum canadense	Common rockrose	6
Hieracium longipilum	Prairie hawkweed	6
Hypericum pyramidatum	Great St. John’s wort	6
Lilium michiganense	Turk’s cap lily	6
Lobelia spicata	Pale spiked lobelia	6
Lupinus perennis	Wild lupine	6
Lysimachia quadrifolia	Whorled loosestrife	6
Napaea dioica	Glade mallow	6
Orobanche uniflora	Cancer root	6
Oxypolis rigidior	Cowbane	6
Polemonium reptans	Jacob’s ladder	6
Polygonum sagitattum	Arrow-leaved tear-thumb	6
Pycnanthemum virginianum	Common mountain mint	6
Ranunculus fascicularis	Early buttercup	6
Ranunculus hispidus	Swamp buttercup	6
Rudbeckia laciniata	Cut-leaved coneflower	6
Salix humilis	Prairie willow	6
Sanguinaria canadensis	Bloodroot	6
Senecio plattensis	Prairie ragwort	6
Silphium integrifolium	Rosinweed	6
Solidago flexicaulis	Zig-zag goldenrod	6
Trillium grandiflorum	Large-flowered trillium	6
Veronicastrum virginicum	Culver’s root	6
Agastache nepetoides	Yellow giant hyssop	5
Amphicarpaea bracteata	Hog peanut	5
Anemone virginiana	Tall anemone	5
Aquilegia canadensis	Wild columbine	5
Arisaema triphyllum	Jack-in-the-pulpit	5
Asclepias incarnata	Swamp milkweed	5
Aster oolentangiensis	Sky-blue aster	5
Aster puniceus	Swamp aster	5
Calamagrostis canadensis	Blue-joint grass	5
Campanula rotundifolia	Harebell	5
Carya ovata	Shagbark hickory	5
Corylus americana	American hazelnut	5
Galium boreale	Northern bedstraw	5
Galium tinctorium	Stiff bedstraw	5
Helianthus divaricatus	Woodland sunflower	5
Heliopsis helianthoides	Ox-eye sunflower	5
Hieracium kalmii	Canada hawkweed	5
Iris virginica	Wild iris	5
Kuhnia eupatorioides	False boneset	5
Lathyrus palustris	Marsh pea	5
Lespedeza capitata	Round-headed bush clover	5
Liatris aspera	Rough blazing star	5
Liparis lilifolia	Purple twayblade	5
Lobelia siphilitica	Great blue lobelia	5
Lysimachia ciliata	Fringed loosestrife	5
Maianthemum canadense	Canada Mayflower	5
Osmorhiza claytoni	Hairy sweet cicely	5
Parthenocissus quinquefolia	Virginia creeper	5
Phryma leptostachya	Lopseed	5
Polygala sanguinea	Field milkwort	5
Polygonum punctatum	Smartweed	5
Prenanthes alba	Lion’s foot	5
Quercus macrocarpa	Bur oak	5
Quercus velutina	Black oak	5
Ranunculus recurvatus	Hooked buttercup	5
Sanicula marilandica	Black snakeroot	5
Scutellaria galericulata	Marsh skullcap	5
Smilacina racemosa	False Solomon’s seal	5
Smilacina stellata	Starry false Solomon’s seal	5
Smilax herbacea	Carrion flower	5
Smilax illinoensis	Greenbrier	5
Solidago rigida	Stiff goldenrod	5
Solidago speciosa	Showy goldenrod	5
Solidago ulmifolia	Elm-leaved goldenrod	5
Sorghastrum nutans	Indian grass	5
Spartina pectinata	Prairie cord grass	5
Stachys palustris	Hedge-nettle	5
Stellaria longifolia	Stitchwort	5
Tradescantia ohiensis	Common spiderwort	5
Triosteum perfoliatum	Tinker’s weed	5
Vernonia fasciculata	Common ironweed	5
Viola pubescens	Yellow wood violet	5
Agastache scrophulariaefolia	Purple giant hyssop	4
Allium canadense	Wild onion	4
Andropogon gerardii	Big bluestem	4
Anemone canadensis	Meadow anemone	4
Arabis lyrata	Sand cress	4
Arnoglossum (Cacalia) atriplicifol	Pale Indian plantain	4
Aster ericoides	Heath aster	4
Aster lanceolatus	Panciled aster	4
Bidens cernuus	Nodding beggar’s tick	4
Campanula americana	Tall bellflower	4
Carex bebbii	Bebb’s oval sedge	4
Carex pellita	Broad-leaved wooly sedge	4
Carex rosea	Rosy sedge	4
Celtis occidentalis	Hackberry	4
Cirsium discolor	Pasture thistle	4
Clematis virginiana	Virgins bower	4
Cryptotaenia canadensis	Honewort	4
Desmodium canadense	Showy tick-trefoil	4
Dioscorea villosa	Wild yam	4
Elymus canadensis	Canada wild rye	4
Erigeron pulchellus	Robin’s plantain	4
Eupatorium altissimum	Tall boneset	4
Eupatorium maculatum	Spotted joe-pye weed	4
Euphorbia corollata	Flowering spurge	4
Euthamia graminifolia	Grass-leaved goldenrod	4
Festuca subverticillata	Nodding fescue	4
Geranium maculatum	Wild geranium	4
Glyceria stricta	Fowl manna grass	4
Helenium autumnale	Sneezeweed	4
Helianthus strumosus	Pale-leaved woodland sunflower	4
Hydrophyllum virginianum	Virginia waterleaf	4
Hypericum punctatum	Dotted St. John’s wort	4
Krigia biflora	False dandelion	4
Laportea canadensis	Wood-nettle	4
Lycopus americanus	Common water-horehound	4
Osmorhiza longistylis	Smooth sweet cicely	4
Panicum oligosanthes	Few-flowered panic-grass	4
Panicum virgatum	Switch grass	4
Penstemon grandiflorus	Large-flowered beard-tongue	4
Physalis virginiana	Lance-leaved ground-cherry	4
Podophyllum peltatum	May-apple	4
Polygonatum biflorum	Smooth Solomon’s seal	4
Ratibida pinnata	Yellow coneflower	4
Ribes americanum	Black currant	4
Rosa sp.	Rose	4
Rudbeckia hirta	Black-eyed Susan	4
Rudbeckia triloba	Brown-eyed Susan	4
Schizachyrium scoparium	Little bluestem	4
Scirpus cyperinus	Wool-grass	4
Scrophularia lanceolata	Early figwort	4
Scrophularia marilandica	Late figwort	4
Senecio pauperculus	Balsam ragwort	4
Silphium perfoliatum	Cup plant	4
Solidago juncea	Early goldenrod	4
Solidago nemoralis	Gray goldenrod	4
Teucrium canadense	Germander	4
Thalictrum dasycarpum	Purple meadow-rue	4
Toxicodendron radicans	Poison ivy	4
Viburnum lentago	Nannyberry	4
Vicia americana	American vetch	4
Anaphalis margaritacea	Pearly everlasting	3
Antennaria neglecta	Field pussytoes	3
Antennaria plantaginifolia	Plantain-leaved pussytoes	3
Apocynum cannabinum	Indian hemp	3
Apocynum sibiricum	Clasping dogbane	3
Aster lateriflorus	Calico aster	3
Aster novae-angliae	New England aster	3
Aster sagittifolius	Arrow-leaved aster	3
Carex blanda	Common wood sedge	3
Carex hystericina	Porcupine sedge	3
Carex pensylvanica	Pennsylvania sedge	3
Celastrus scandens	Climbing bittersweet	3
Epilobium coloratum	Cinnamon willow-herb	3
Eragrostis spectabilis	Purple Lovegrass	3
Geum aleppicum	Yellow avens	3
Hackelia virginiana	Stickseed	3
Heracleum lanatum	Cow parsnip	3
Lactuca biennis	Tall blue lettuce	3
Leersia oryzoides	Rice cut grass	3
Mentha arvensis	Wild mint	3
Monarda fistulosa	Wild bergamot	3
Monarda punctata	Horse mint	3
Prunus americana	Wild plum	3
Prunus serotina	Wild black cherry	3
Prunus virginiana	Choke cherry	3
Ribes cynosbati	Gooseberry	3
Sambucus canadensis	Elderberry	3
Solidago gigantea	Late goldenrod	3
Triodanis perfoliata	Venus looking glass	3
Verbena hastata	Blue vervain	3
Verbena stricta	Hoary vervain	3
Viola soraria	Door-yard violet	3
Zanthoxylum americanum	Prickly ash	3
Agrimonia gryposepala	Tall agrimony	2
Apocynum androsaemifolium	Spreading dogbane	2
Asclepias verticillata	Whorled milkweed	2
Carex stipata	Common fox sedge	2
Carex vulpinoidea	Brown fox sedge	2
Circaea lutetiana	Enchanter’s nightshade	2
Cornus racemosa	Gray dogwood	2
Echinocystis lobata	Wild cucumber	2
Erechtites hieracifolia	Fireweed	2
Erigeron philadelphicus	Marsh fleabane	2
Erigeron strigosus	Daisy fleabane	2
Galium aparine	Annual bedstraw	2
Gaura biennis	Biennial gaura	2
Geum canadense	White avens	2
Helianthus grosseserratus	Saw-tooth sunflower	2
Helianthus tuberosus	Jerusalem artichoke	2
Lactuca canadensis	Tall lettuce	2
Lobelia inflata	Indian tobacco	2
Potentilla simplex	Old-field cinquefoil	2
Rhus glabra	Smooth sumac	2
Silene antirrhina	Sleepy catchfly	2
Verbena urticifolia	White vervain	2
Achillea millefolium	Yarrow	1
Asclepias syriaca	Common milkweed	1
Aster pilosus	Hairy aster	1
Eupatorium rugosum	White snakeroot	1
Fragaria virginiana	Wild strawberry	1
Oenothera biennis	Common evening-primrose	1
Polygonum pensylvanicum	Lady’s thumb	1
Prunella sp.	Self-heal	1
Ranunculus abortivus	Small-flowered buttercup	1
Solidago canadensis	Common goldenrod	1
Typha latifolia	Cattail	1
Urtica sp.	Nettle	1
Oxalis stricta	Yellow wood-sorrel	0
Potentilla norvegica	Rough cinquefoil	0