Rare Species Guide

  Basis for Listing

As of 2008, approximately 50 occurrences of Dryopteris goldieana (Goldie's woodfern) had been documented in Minnesota. Most of the records are from hardwood forests in the five southeastern counties, although there is a small cluster of records from the vicinity of Leech Lake and Lake Winnibigoshish in the north central part of the state. These north central records are considered to represent an unusual disjunct population that has greater than normal biological significance. If the frequency of occurrence is a valid measure of rarity, then D. goldieana is rare indeed. Even in the southeastern part of the state where it is most likely to be found, and in habitats that would appear to be ideal, the chances of finding D. goldieana are perhaps 50 to 1. Rarity alone is not the only factor that must be considered; vulnerability of its habitat and population trends must also be examined. Dryopteris goldieana was listed as a special concern species in Minnesota in 1984.

  Description

Dryopteris goldieana is a large, conspicuous fern of forest habitats. The leaves are non-glandular, herbaceous in texture, and they die back in the winter. They can grow as large as 120 cm (3.9 ft.) long and 40 cm (15.7 in.) wide, and they arise in a clump from a short rhizome. The leaf blade is ovate in outline and it tapers abruptly at the tip. The pattern of division is pinnate-pinnatifid, or sometimes bipinnate at the base. The smallest segments of the leaf blade (pinnae) are ovate-lanceolate in shape and broadest above the base. The petiole is about 1/3 of the length of the entire leaf and conspicuously scaly. The scales are broad, and dark in color with a lighter border. Dryopteris goldieana is one of the largest ferns in Minnesota, and it usually stands out in its forest habitat. Confusion with a sterile leaf of Osmunda claytoniana (interrupted fern) is possible, but unlike O. claytoniana, the leaf margins of D. goldieana have narrow, pointed teeth that curve inward.

  Habitat

In Minnesota, D. goldieana is known to occur only in mesic hardwood forests of the type typically dominated by Acer saccharum (sugar maple), Tilia americana (basswood), and Quercus rubra (northern red oak). The northern habitats also contain Thuja occidentalis (northern white cedar) and Betula allegheniensis (yellow birch). The shrub component of these forests is rather sparse, but may include Carpinus caroliniana ssp. virginiana (blue beech), Ribes spp. (gooseberries), and Prunus virginiana (chokecherry). These are all fire-excluded forests where cycling of organic material happens through slow decomposition rather than periodic fires. Soils are usually loam derived from calcareous till.

  Biology / Life History

The biology and life history of D. goldieana has not been studied, but a few tentative conclusions can be drawn from observations. Dryopteris goldieana is a long-lived fern of stable forest interiors. It appears to be little bothered by herbivory, although it is likely grazed by various insects and possibly by native herbivores such as white-tailed deer (Odocoileus virginianus). It is capable of spreading short distances by vegetative offshoots, which can result in the development of small clonal colonies. This process is relatively slow and constrained by competition from roots of other plants. Dispersal over long distances is accomplished only by spores, which can be carried great distances on wind currents.

The leaves of D. goldieana are considered semi-evergreen and can be seen from the time they reach full size in early June until they are covered by snow in winter.

  Conservation / Management

Intact and full-functioning examples of the mesic forest habitats of D. goldieana will require very little active management. The main goals should be to exclude motorized vehicles and livestock to avoid soil damage, restrict logging in order to maintain the integrity of the tree canopy, and visually monitor the vegetation to detect any invasive species that might appear.

  Conservation Efforts in Minnesota

A number of D. goldieana sites occur on state and national forest lands which are publicly owned and managed by the Minnesota Department of Natural Resources and the U.S. Forest Service. These sites are safe from private development but are being managed for timber production. This could potentially expose D. goldieana to the effects of road construction, log landings, and small patches of clearcuts or "regeneration cuts". The Cass County Land Department has established logging procedures in their Forest Resources Management Plan to protect known locations of D. goldieana on county lands. Harvest can occur only when the ground is frozen with no direct action over the plants, and 80% of the surrounding canopy cover must be retained.

  References and Additional Information

Montgomery, J. D., and W. H. Wagner, Jr. 1993. Dryopteris. Pages 280-288 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 2. Oxford University Press, New York, New York.

Smith, W. R. 2023. Ferns and lycophytes of Minnesota: the complete guide to species identification. University of Minnesota Press, Minneapolis. 368 pp.