| Armoracia lacustris |
| Lake cress |
Key Characteristics
Emergent aquatic plant of marshes; underwater leaves alternate, twice-pinnate on a central axis, falling off when lifted from water.
Status and Rank
- State Status: T - Threatened (legally protected)
- State Rank: S2 - Imperiled
- Global Rank: G4? - Apparently secure (inexact)
Occurrences
| County Name | Number of Occurrences | Year Last Observed |
|---|---|---|
| Alpena | 3 | 1984 |
| Cheboygan | 6 | 1984 |
| Gratiot | 1 | 1889 |
| Ionia | 1 | 1889 |
| Iosco | 1 | 1937 |
| Luce | 1 | 1971 |
| Mackinac | 1 | 1975 |
| Macomb | 2 | 1900 |
| Marquette | 1 | 1976 |
| Mason | 1 | 1932 |
| Muskegon | 1 | 1898 |
| Presque Isle | 4 | 1981 |
![Occurrence Map for [Sname]](/mnfi/maptmp/NFR_Distributions12590214495740.png)
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
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
This species requires high water quality and natural hydrology.
General Survey Guidelines
Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgment of the investigator.
Survey Methods
- Meander search
Survey Period: From first week of July to fourth week of September
Survey Comments: 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
- 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.