Plants and Animals

Rorippa aquatica Lake cress

species photo
Donald H. Les

Key Characteristics

Emergent aquatic plant of lake margins and slowly moving streams; underwater leaves alternate, twice-pinnate on a central axis, falling off when lifted from water.

Status and Rank

US Status:
State Status: T - Threatened (legally protected)
Global Rank: G4? - Apparently secure (inexact)
State Rank: S2 - Imperiled

Occurrences

CountyNumber of OccurrencesYear Last Observed
Alpena31984
Cheboygan61984
Gratiot11889
Ionia11889
Iosco11937
Luce11971
Mackinac11975
Macomb21900
Marquette11976
Mason11932
Muskegon11898
Presque Isle41981

Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.

Habitat

An aquatic plant, this species is found in quiet, shallow water along lake margins and back water areas of slowly moving streams. It roots in organic or sandy substrates.

Natural Community Types

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Associated Plants

Water-plantain, sedges, spike-rush, northern manna grass, cut grass, smartweed, arrowhead, bur-reed, cat tails, wild rice, water-milfoil, watercress, and great duckweed.

Management Recommendations

This species requires high water quality and natural hydrology.

Survey Methods

Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgment of the investigator.

  • Meander search

    • Survey Period: From first week of July to fourth week of September

      Survey Method Comment:
      Leaves easily disarticulate from stem and serve as propagules, and thus may be found separately in water

References

Survey References

  • Elzinga, C.L., D.W. Salzer, and J.W. Willoughby. 1998. Measuring and Monitoring Plant Populations. The Nature Conservancy and Bureau of Land Management, Denver. BLM Technical Reference 1730-1. 477pp.
  • Goff, G.F., G.A. Dawson, and J.J. Rochow. 1982. Site examination for Threatened and Endangered plant species. Environmental Management 6(4): 307-316
  • Nelson, J.R. 1984. Rare Plant Field Survey Guidelines. In: J.P. Smith and R. York. Inventory of rare and endangered vascular plants of California. 3rd Ed. California Native Plant Society, Berkeley. 174pp.
  • Nelson, J.R. 1986. Rare Plant Surveys: Techniques For Impact Assessment. Natural Areas Journal 5(3):18-30.
  • Nelson, J.R. 1987. Rare Plant Surveys: Techniques for Impact Assessment. In: Conservation and management of rare and endangered plants. Ed. T.S. Elias. California Native Plant Society, Sacramento. 8pp.

Technical References

  • Flora of North America Editorial Committee. 2010. Flora of North America, North of Mexico. Volume 7: Magnoliophyta: Salicaceae to Brassicaceae. Oxford Univ. Press. New York, NY. 797 pp.
  • Gleason, H. A., and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second edition. The New York Botanical Garden, Bronx. 910pp.
  • Godfrey, R.K. and Wooten. 1981. Aquatic and Wetland Plants of Southeastern United States. Dicotyledons. University of Georgia Press, Athens. 712pp.
  • Gray, A. 1950. Gray's Manual of Botany; eighth ed. Van Nostrand Reinghold, New York. 1632pp.
  • Holmgren, N.H. 1998. Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the vascular plants of Northeastern United States and adjacent Canada. New York Botanical Garden, Bronx. 937pp.
  • Voss, E. G. 1985. Michigan Flora. Part II. Dicots (Saururaceae-Cornaceae). Bulletin of the Cranbrook Institute of Science and University of Michigan Herbarium. 724pp.