Plants and Animals

Asplenium rhizophyllum Walking fern

species photo
MNFI Staff
species photo
MNFI Staff
species photo
William W. Brodovich

Key Characteristics

Small fern forming dense colonies by tip-rooting; fronds lanceolate with heart-shaped bases and very long tapering tips; occurring on large moss-covered dolomite boulders.

Status and Rank

US Status:
State Status: T - Threatened (legally protected)
Global Rank: G5 - Secure
State Rank: S2S3 - Rank is uncertain, ranging from imperiled to vulnerable

Occurrences

CountyNumber of OccurrencesYear Last Observed
Alpena11952
Berrien11994
Chippewa62013
Delta11979
Dickinson32001
Houghton11970
Leelanau11982
Mackinac202014
Menominee11905

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

Found on large moss-covered boulders in northern hardwoods and occasionally conifers within the Niagara Escarpment region. Is it also known from alkaline bedrock outcrops in the western Upper Peninsula, from sinkholes in northeastern Lower Michigan, and very rarely on large, rotting, fallen trees in rich forests. The single southern Michigan occurrence is found on sandy conglomerate boulders within a floodplain forest. Topographically this species usually occurs at or above the 700 ft contour line.

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

Polypody, maidenhair spleenwort, hart's tongue fern, green spleenwort, fragile fern, Braun's Christmas fern, northern holly fern, sugar maple, Eastern hemlock, beech, yellow birch, basswood, white pine, red oak, white cedar, white birch, ironwood, American elm, balsam fir, white baneberry, red baneberry, wild leek, wild sarsaparilla, jack-in-the-pulpit, blue cohosh, enchanter's nightshade, bunchberry, blue-bead lily, Canada mayflower, Solomon's seal, false spikenard, twisted stalk, bellwort, star flower, nodding trillium, common trillium, maiden hair fern, lady fern, rattlesnake fern, spinulose woodfern, stiff clubmoss, shining clubmoss, ground pine, striped maple, leatherwood, fly honeysuckle, and maple-leaf viburnum.

Management Recommendations

Generally requires shade and moist, moss-covered limestone or dolomite boulders. Species is likely sensitive to drying and scorching from overexposure to sunlight. Maintain overstory and minimize development and fragmentation. When possible, leave large tracts of unharvested forests and allow natural processes (growth, senescence, wind throw, fire, disease, insect infestation, etc) to operate unhindered. If forest is being managed for timber, minimize fragmentation, leave long periods of recuperation between harvests (50-70 yrs.), preserve as much area as possible in a forested matrix, and maintain a range of canopy closure comparable to pre-harvest closure.

Survey Methods

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

  • Meander search

    • Survey Period: From first week of May to fourth week of October

      Survey Method Comment:
      Search cliff faces, large limestone/dolomite boulders, and low outcrops

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. 1993. Flora of North America, North of Mexico. Volume 2: Pteridophytes and Gymnosperms. Oxford University Press, New York. 475pp.
  • 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.
  • 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.
  • Lellinger, D.B. 1985. A field manual of ferns and fern allies of the United States and Canada.. Smithsonian Institute Press, Washington D.C. 389pp.
  • Mickel, J.T. 1979. How to know the ferns and fern allies. The Pictured Key Nature Series. William C. Brown Company, Dubuque. 229pp.