Plants and Animals

Polygala cruciata Cross-leaved milkwort

species photo
Gary Reese
species photo
Brad Slaughter

Key Characteristics

Small forb (30 cm) of coastal plain marshes; leaves narrowly elliptic and mostly in whorls of 4; flowers purple to green, borne in dense clusters on top of the stem.

Status and Rank

US Status:
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G5 - Secure
State Rank: S3 - Vulnerable

Occurrences

CountyNumber of OccurrencesYear Last Observed
Allegan32013
Berrien41999
Cass11906
Jackson11893
Kalamazoo21954
Monroe11928
Muskegon32006
Newaygo22006
St. Clair11914
Van Buren31988
Wayne11991

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

Cross-leaved milkwort is found in areas with a fluctuating water table such as coastal plain marshes, sandy lake edges, dune swales, seepages, sandy marshes, sandy and peaty edges of wetlands and intermittent wetlands.

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

Bluejoint grass, cordgrass, rush, sedges, twig-rush, shrubby cinquefoil, swamp milkweed, big bluestem, Indian grass, Sullivant's milkweed, purple milkweed, swamp thistle, marsh blazing star, whorled loosestrife, grass-of-Parnassus, smooth hedge nettle, swamp rose, Missouri ironweed, joe-pye weed, common bone set, and spike-rush.

Management Recommendations

To maintain this species, protect habitat and maintain hydrology and natural disturbance regimes. This species most likely requires open conditions. Prevent woody plant encroachment by using prescribed fire or manual brush removal. Much of this habitat has been lost and degraded via conversion to agriculture, development, alterations of ground water hydrology and fire suppression.

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 August to fourth week of September

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

  • Coffin, B. and L. Pfannmuller, eds. 1988. Minnesota's Endangered Flora and Fauna. University of Minnesota Press, Minneapolis. 473pp.
  • Cooperrider, T.S. 1995. The Dicotyledonae of Ohio Part 2. Linaceae through Campanulaceae. Ohio State University Press, Columbus. 656pp.
  • 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.
  • Swink, F. and G. Wilhelm. 1994. Plants of the Chicago Region, 4th ed. Indiana Academy of Science, Indianapolis. 921pp.
  • Voss, E. G. 1985. Michigan Flora. Part II. Dicots (Saururaceae-Cornaceae). Bulletin of the Cranbrook Institute of Science and University of Michigan Herbarium. 724pp.