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Wisconsin Plant of the Week

Site Information:
Origin of the Site
Wisconsin  Map with County Names
Native and Introduced Species
Invasive Species
Protected Species

Origin of the Site

This site grew out of the need for WDNR staff, most of whom are not botanists, to become familiar with the vegetation of Wisconsin as part of doing their jobs. Wisconsin has over 2500 vascular plants, so as you might expect people had the most success, not with crash courses, but with learning in small doses over a long period -- a few plants at a time, and whenever possible with live material in the field or brought back to the office.  This site is the electronic version of that training. Each week, more or less, the site features a plant species along with some basic information on its taxonomy, ecology and natural history. Photos of the plants are taken expressly to help identify them easily and definitively in the field. Subscribers get each new plant delivered to their mailbox, so keeping up requires only a click of the mouse.  Past featured plants are archived for review anytime and the related sites section has good resources for further information.


The site lists common names for each plant. Since these often mean different things to different people, we’ve organized the plants based on scientific names that are universal. We include both the species name and the family to which that species belongs. The value to noting the family is that recognizing family characters allows one to recognize a new species as belonging to that family without knowing each species individually.  For example, all the species in the mustard family (Brassicaceae) have the same flower structure -- 4 petals and six stamens, 4 long and 2 short. So you can recognize a new plant as a mustard without learning each of the more than 80 species that occur in Wisconsin.

The species name consists of two words: the first is the name of the genus to which the plant is assigned and the second is the specific epithet.  For example, marsh marigold is the species Caltha palustris; Caltha is the genus; palustris is the specific epithet. All scientific names are treated as Latin, but the origin or root of the words may come from many sources at the discretion of the person who names the plant.  Many scientific names are useful descriptors once one understands the origin of the latinized name.

The rules governing scientific names, set forth in the International Code of Botanical Nomenclature, can be applied once one has settled on the taxonomic status of the plant to be named.  Like most fields, plant taxonomy has considerable room for differences of opinion, and the most recent classification is not always the best. Assignments to plant families and genera change as we learn more about how species are related and so accepted scientific names change occasionally as well.

Most readers (like the author of this site) are not plant taxonomists, so to avoid confusion with other references this section explains the nomenclature used here:

Ferns, fern allies and gymnosperms follow the nomenclature in Flora of North America (1993, Vol 2). The flowering plants follow Gleason (1981) with two exceptions to be consistent with the Checklist of the Vascular Plants of Wisconsin, maintained by the Wisconsin State Herbarium: Hypericaceae and Lobeliaceae are recognized as families.  Where the scientific name has changed recently the currently accepted name is listed and mention is made of the previously accepted synonym(s). For example, based on phylogenetic evidence the genus Hepatica has been included with Anemone, and some species in the genus Scirpus have been included in Schoenoplectus or Bolboschoenus.  The Checklist gives a complete list of accepted and synonymous names.

Native and Introduced Species

Native plants are those assumed to have been present somewhere in Wisconsin prior to European settlement.  Introduced species were brought into the state from elsewhere.  Many introduced species came from Europe or Asia and some came from other parts of North America.  The distinction between native and introduced is not always as clear as one would expect. For some species there is considerable debate over whether a plant is native or introduced and for some of these it may be impossible to tell for certain.  A species also may be native in some areas of the state and introduced in others.

Introduced species may be divided further into categories that are actually points along a continuum.  For example, some are originally planted but now well established (naturalized); normally cultivated but now growing and spreading on their own (escaped); or established incidentally but not yet wide spread or persistent (adventive). 

The distinction between native and introduced species plants at this site is consistent with the Wisconsin State Herbarium listing.  No attempt is made to distinguish to which introduced category a species belongs.

Invasive Species

Three species are considered “noxious weeds” in Wisconsin: Cirsium arvense (Canada thistle), Convolvulus arvensis (Field bindweed) and Euphorbia esula (Leafy spurge). Municipal law, s. 66.99 Wis. Stats., requires “every person shall destroy all noxious weeds on lands which he shall own, occupy or control.”

Two species are considered “nuisance weeds”: Lythrum salicaria (Purple loosestrife) and Rosa multiflora (Multiflora rose).   Municipal law, s. 66.955 Wis. Stats, prohibits propagation of nuisance weeds.

These species have a large negative impact on the State’s agricultural industry. Many other invasive or potentially invasive  species pose a threat to agricultural lands and to native habitats.  More information on these species and control methods is available from WDNR’s Bureau of Endangered Resources http://www.dnr.state.wi.us/org/land/er/invasive_species.htm

Protected Species

WDNR maintains a “Wisconsin Natural Heritage Working List” that includes species sufficiently rare to merit some level of protection.  The protection categories are defined as follows:

  • State Endangered -- Wisconsin Endangered Species: any species whose continued existence as a viable component of the State's wild animals or wild plants is determined by the Department  to be in jeopardy on the basis of scientific evidence, s. 29.604, Wis. Stats.
  • State Threatened -- Wisconsin Threatened Species: any species which appears likely, within the foreseeable future, on the basis of scientific evidence to become endangered, s. 29.604, Wis. Stats.
  • Special Concern -- Species about which some problem of abundance or distribution is suspected but not yet proved.  The main purpose of this category is to focus attention on certain species before they become threatened or endangered.

Based on accepted taxa in the Checklist there are 64 Endangered, 57 Threatened and 152 Special Concern plant taxa. The Wisconsin Natural Heritage Working List is revised frequently.  A current copy is available from the WI Natural Heritage Program, Bureau of Endangered Resources, http://www.dnr.state.wi.us/org/land/er.rare.htm


Information on each plant of the week comes from a variety of sources, including the following texts.  Additional information was obtained from the websites listed on the Related Sites page.

Argus, G.W. 1964.  Preliminary Reports on the Flora of Wisconsin.  No. 51. Salicaceae.  The Genus Salix, Wisconsin Acad. Sciences, Arts and Letters, 53, pp. 217-272.

Borman, S., R. Korth and J. Temte. 1997.  Through the Looking Glass . . . A Field Guide to Aquatic Plants, Wisconsin Lakes Partnership, Stevens Point, WI, 248 pp.

Case, F. W., Jr. 1987. Orchids of the Western Great Lakes Region, Cranbrook Institute of Science Bulletin 48, 251 pp.

Courtenay, B. and J. H. Zimmerman. 1972. Wildflowers and Weeds, Van Nostrand Reinhold Co., New York, 144 pp.

Curtis, J. C. 1959. The Vegetation of Wisconsin, University of Wisconsin Press, Madison, WI, 657 pp.

Eggers, S. D. and D. M. Reed.  1997. Wetland Plants and Plant Communities of Minnesota and Wisconsin, U. S. Army Corps of Engineers St. Paul District, 263 pp.

Fassett, N. C. 1951. Grasses of Wisconsin:  The Taxonomy, Ecology and Distribution of the Gramineae Growing in the State without Cultivation, University of Wisconsin Press, Madison, WI.

Fassett, N. C. 1957. A Manual of Aquatic Plants, University of Wisconsin Press, Madison, WI 405 pp.

Fassett, N. C. 1976. Spring Flora of Wisconsin, 4th ed., University of Wisconsin Press, Madison, WI, 413 pp.

Flora of North America Editorial Committee. 1993. Flora of North America North of Mexico, Vol. 2: Pteridophytes and Gymnosperms, Oxford University Press, 496 pp.

Flora of North America Editorial Committee. 1997. Flora of North America North of Mexico, Vol. 3: Magnoliophyta: Magnoliidae and Hamamelidae, Oxford University Press, 616 pp.

Flora of North America Editorial Committee. 2000. Flora of North America North of Mexico, Vol. 22: Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part) and Zingiberidae, Oxford University Press, 384 pp.

Gleason, H. A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada, 2nd ed., New York Botanical Garden, New York, 910 pp.

Gledhill, D. 1989. The Names of Plants, 2nd ed., Cambridge University Press, 202 pp.

Holmgren, N. H. 1998.  Illustrated Companion to Gleason and Cronquist’s Manual, New York Botanical Garden, New York, 937 pp.

Kowal, R. R. (ed.) 1991. Taxonomy and Evolution of Composites, University of Wisconsin--Milwaukee Field Station.

Lellinger, D. B. 1985. A Field Manual of the Fern and Fern-Allies of the United States and Canada, Smithsonian Institution Press, Washington, D.C. 389 pp.

Newcomb, L. 1977.  Newcomb’s Wildflower Guide, Little, Brown and Co., Boston, MA, 490 pp.

Niering, W. A. and N. C. Olmstead, The Audubon Society Field Guide to North American Wildflowers, Alfred Knopf, New York, 885 pp.

Shosteck, R. 1974. Flowers and Plants, An International Lexicon with Biographical Notes. Quadrangle, The New York Times Book Co., New York.

Swink, F. and G. Wilhelm. 1994.  Plants of the Chicago Region, 4th ed., Indiana Academy of Science, Indianapolis, IN, 921 pp.

USDA--Soil Conservation Service. Midwestern Wetland Flora, Midwest National Technical Center, Lincoln, NB.

Voss, E. G. 1972. Michigan Flora Part I Gymnosperms and Monocots, Cranbrook Institute of Science, Bulletin 55 and University of Michigan Herbarium, 488 pp.

Voss, E. G. 1985. Michigan Flora Part II Dicots (Saururaceae--Cornaceae), Cranbrook Institute of Science, Bulletin 59 and University of Michigan Herbarium, 724 pp.

Voss, E. G. 1996. Michigan Flora Part III Dicots (Pyrolaceae -- Compositae), Cranbrook Institute of Science, Bulletin 61 and University of Michigan Herbarium, 622 pp.


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