Robert W. Freckmann Herbarium
University of Wisconsin - Stevens Point

Vascular Plants

Plants of Wisconsin

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Natural Communities:
Geological Features and Primary Communities


Click on community name for photo gallery.

Algific talus slope
This rare community of southwestern Wisconsin’s Driftless Area consists of steep slopes of fractured limestone (dolomite) rock that retains ice and emits cold air throughout the growing season. The cold microhabitats enable the persistence of northern species and "periglacial relicts" such as northern monkshood (Aconitum noveboracense) and rare terrestrial snails. The woody overstory is often sparse, with scattered small black ash (Fraxinus nigra) and white birch (Betula papyrifera). Mountain maple (Acer spicatum), a northern shrub, may be frequent and extensive beds of bulblet fern (Cystopteris bulbifera) and mosses are characteristic.

Alkaline clay bluff
Steep, clay bluffs occur along some stretches of the Great Lakes shorelines and less commonly inland on streams draining into Lake Superior and Lake Michigan. Vegetative cover ranges from forested with pines (Pinus resinosa and P. strobus), white cedar (Thuja occidentalis) and white birch (Betula papyrifera), to bare clay with only a few herbs present. Buffaloberry (Sheperdia canadensis) is a characteristic shrub, but more typically, alders(Alnus incana and A. crispa), as well as herbs such as Canada goldenrod (Solidago canadensis) and pearly everlasting (Anaphalis margaritacea) are dominant. Both native and exotic pioneers such as fireweed (Epilobium angustifolium) and Canada thistle (Cirsium arvense) are common, especially on unstable sites. But it is the semi-stabilized “weeping” bluffs that are of the greatest biological interest. Golden sedge (Carex aurea), orchids and calciphilic fen species may colonize such sites, which can be local repositories of rare or otherwise noteworthy species.

Alvar
This rare community consists of areas of thin discontinuous soil overlying horizontal beds of limestone or dolomite in the vicinity of Great Lakes shorelines. They are characterized by relatively low tree cover and a distinctive biota which includes elements of rock pavement, prairie, savanna and boreal forest communities. Among these are regional endemics, some very rare. This community type is much more common and better-developed in Michigan and Ontario than in Wisconsin. Small coniferous and deciduous trees (cedar, fir, pine, oak, aspen, birch) are scattered among an assemblage of species that can include big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), Indian-grass (Sorghastrum nutans), and wood lily (Lilium philadelphicum), as well as shoreline plants such as silverweed (Potentilla anserina). and dwarf lake iris (Iris lacustris).

Bedrock glade
These are xeric, sparsely vegetated non-vertical bedrock exposures with very thin, often discontinous soils. The rock types vary from quartzite (Baraboo Hills, McCaslin Mountain), to basalt (lower St. Croix River valley), to granite (northeastern Wisconsin). The flora can include prairie, savanna, or barrens components, some at their northern range limits. Trees and shrubs are sparse and may include pines, oaks, and cherries. Xerophytic pteridophytes such as rusty woodsia (Woodsia ilvensis) and rock spikemoss (Selaginella rupestris) are characteristic, as are lichens and mosses.

Bedrock shore
Wave-splashed bedrock shoreline ledges are best developed on sandstone in the Apostle Islands of Lake Superior. Stunted trees of white cedar (Thuja occidentalis), white birch (Betula papyrifera), showy mountain-ash (Sorbus decora) and green alder (Alnus crispa) are often present in crevices. Common herbs are ticklegrass (Agrostis hyemalis), fireweed (Epilobium angustifolium), and Canada goldenrod (Solidago canadensis), but the flora often includes unusual plants such as bird's-eye primrose (Primula mistassinica), brook lobelia (Lobelia kalmii), and three-toothed cinquefoil (Potentilla tridentata).

Dry cliff
These dry vertical bedrock exposures occur on many different rock types, which may influence species composition. Scattered pines, oaks, or shrubs often occur. However, the most characteristic plants are often the ferns, common polypody (Polypodium vulgare) and rusty woodsia (Woodsia ilvensis), along with herbs such as columbine (Aquilegia canadensis), harebell (Campanula rotundifolia), pale corydalis (Corydalis sempervirens), juneberry (Amelanchier spp.), bush-honeysuckle (Diervilla lonicera), and rock spikemoss (Selaginella rupestris).

Felsenmeer
Quartzite or other metamorphic or igneous rock talus slope or “felsenmeer” communities characterized by all-summer upwellings of cool, moist air near or at their bases. It is not certain whether year-round ice deposits are responsible for the upwelling. Glacière talus forms as the result of periglacial frost and ice-wedging; quartzite, in particular, is a brittle rock that is susceptible to frost-wedging. The talus slopes themselves consist of lichened boulders ranging from 0.25-1 m in diameter. Nearly all sites (except the one at Devils Lake, Wisconsin) occur in areas that were glaciated during the Pleistocene. At the best-developed examples (Ouimet and Cavern Lake Canyons in Ontario, the Blue Hills Felsenmeer in Wisconsin), a double talus slope embracing a V-shaped valley may be present.

Great Lakes alkaline rockshore
These are creviced, wave-splashed, nearly horizontal dolomite ledges along Lake Michigan on the Door Peninsula. Depending on lake levels, large expanses of this habitat may be either inundated or exposed during a given year. Common members of this community are the shrubs ninebark (Physocarpus opulifolius), shrubby cinquefoil (Potentilla fruticosa), and the herbs silverweed (Potentilla anserina), goldenrods (especially Solidago hispida), brook lobelia (Lobelia kalmii), gentians (Gentiana spp.), grasses-of Parnassus (Parnassia spp.), Indian paint-brush (Castilleja coccinea), low calamint(Calamintha arkansana) and many other calciphiles. Plants endemic to the Great Lakes shores are significant components of some stands.

Great Lakes beach
This beach community usually occurs in association with active dune systems. The beaches of the Great Lakes are extremely dynamic features, strongly influenced by water level changes and storm events. They support a suite of very specialized organisms, although unprotected shorelines may be entirely unvegetated. The plant species found in this community include (along Lake Michigan) seaside spurge (Euphorbia polygonifolia) and American sea-rocket (Cakile edentula).

Great Lakes dune
The dominant plant in these semi-stabilized, open dunes along Great Lakes shorelines, is usually the sand-binding marram grass (Ammophila breviligulata). Frequent associates are common juniper (Juniperus communis), Canada wild-rye (Elymus canadensis), false-heather (Hudsonia tomentosa), beach-pea (Lathyrus japonicus), beach wormwood (Artemisia campestris), sand cherry (Prunus pumila), and various willows (Salix spp.). Two plants endemic to the Great Lakes region, pitcher's thistle (Cirsium pitcheri) and Lake Huron tansy (Tanacetum huronense; possibly now extirpated in Wisconsin), occur in this community along Lake Michigan.

Inland beach
The beaches of inland lakes that experience enough water level fluctuation to prevent the development of a stable shoreline forest or other community may, instead support a specialized biota adapted to sandy or gravelly littoral habitats. The shorelines of such lakes (usually seepage lakes) may be subject to fluctuations of as much as several meters over a few years or decades. The alternation of high and low periods maintains populations of the beach specialists over time, including some rare species of unusual geographic affinity such as the Atlantic Coastal Plain of the eastern United States.

Moist cliff
This "micro-community" occurs on shaded (by trees or the cliff itself because of aspect), moist to seeping mossy, vertical exposures of various rock types, most commonly sandstone and dolomite. Common species are columbine (Aquilegia canadensis), the fragile ferns (Cystopteris bulbifera and C. fragilis), wood ferns (Dryopteris spp.), rattlesnake-root (Prenanthes alba), and wild sarsaparilla (Aralia nudicaulis). The rare flora of these cliffs vary markedly in different parts of the state; Driftless Area cliffs might have northern monkshood (Aconitum noveboracense), those on Lake Superior, butterwort (Pinguicula vulgaris), or those in Door County, green spleenwort (Asplenium viride).

Riverine gravel bar


Talus forest



Offsite resources:
Virginia Kline's collection of the Vegetation of Wisconsin
Michigan Natural Features Inventory Community descriptions

Vascular Plants

Plants of Wisconsin

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