Laccaria trullisata (Ellis) Peck
Agaricus trullissatus, Clitocybe trullissata, Laccaria trullissata
Basis for Listing
Laccaria trullisata (sand-loving laccaria) has been collected at two sites in Anoka County and at one site each in Sherburne, Dakota, Crow Wing and St. Louis counties. Its requirement for open, sandy areas with tree species of Pinus spp. (pine), Quercus spp. (oak), or Betula spp. (birch) makes its populations vulnerable to disturbance from human activity, including beachfront development. Laccaria trullisata was listed as a special concern species in Minnesota in 1996.
Mushroom caps of L. trullisata are 15-70 mm (0.6-2.8 in.) broad, rounded to flat, with a dry surface that is minutely hairy. Cap color is grayish purple when very young, becoming red-brown, brown, or buff with age; flesh is pale purple. Gills are close to subdistant, thick, waxy, and of a dark violet color. Stems are 40-90 mm (1.6-3.5 in.) long, 6-23 mm (0.24-0.91 in.) thick, and club-shaped. Typically buried in sand, stem surfaces are dry, minutely hairy, and longitudinally striate, with a color similar to the cap. Flesh is solid, and basal mycelium is violet. Spores are white, 13.8-20.2 µm x 5.5-8.3 µm, long-elliptical to spindle-shaped, and very finely roughened. Laccaria maritima (sand deceiver), found in dune habitats in northern Europe, Greenland, and eastern Canada, has shorter spiny elliptical spores. Laccaria trullisata is easily recognized by its purplish colors, thick waxy gills with white spores, and its habit of growing buried in sand. Microscopically, the nearly smooth elongated spores are distinctive within Laccaria.
Laccaria trullisata is restricted to sparsely-vegetated sandy areas, such as dunes; along ocean, lake, and river shores; or in post-glacial sand plains. The population in Crow Wing County grows near a lake in open, sandy areas with Pinus spp., Betula spp., Quercus spp., and Populus spp. (aspen) (fire-dependent forest/woodland system). The Anoka and Sherburne county populations were found on the Anoka Sand Plain in either areas of sand blowouts with Q. rubra (northern red oak) or Pinus spp. and Hudsonia tomentosa (beach heather), or in open oak savanna (southern dry savanna). The St. Louis County population occurred in sand at a woodland edge with Pinus strobus (white pine), Betula papyrifera (paper birch), Juniperus spp. (bush juniper), as well as Ammophila breviligulata ssp. breviligulata (beach grass) and H. tomentosa (Lake Superior Sand/Gravel/Cobble Shore, Beachgrass Dune).
Biology / Life History
Laccaria trullisata is an ectomycorrhizal fungus that is a beneficial root symbiont. It can form mycorrhizae with Pinus spp. (Mueller 1992) but is also assumed to form associations with sand and dune plants such as Hudsonia tomentosa (Redhead 1989). In the western Great Lakes, Pinus spp., Quercus spp., and Betula spp., alone or in combination, have been present and are potential symbionts. Mushroom fruitbodies can be produced in the fall from the perennial underground mycelium. Dispersal is via wind-borne spores or locally by extension of the mycelium between neighboring plant hosts. Laccaria trullisata is an eastern maritime-Great Lakes endemic occurring along the Atlantic and Gulf Coasts, around the shores of the Great Lakes, and inland on lake or river shores and on sand plains.
Conservation / Management
Laccaria trullisata has been found near a lake in Crow Wing County (Pine Moraines & Outwash Plains Subsection), in Anoka and Sherburne counties on the Anoka Sand Plain Subsection, at a sandy site in Dakota County (Oak Savanna Subsection), on sandy lakeshore in St. Louis County (North Shore Highlands Subsection) and in neighboring Wisconsin. It occurs in eastern North America south to the Gulf Coast, west to Iowa, and is at the northwestern limits of its range in Minnesota. Laccaria trullisata is a distinctive species adapted to a particular ecosystem. The large fruitbodies are easily found if they are present when one is searching the exposed sand in appropriate open habitats. Although additional survey work may yield additional locations, habitat disturbance by humans is a threat and is expected to increase along beachfronts. Ectomycorrhizal fungi in general are sensitive to nitrogen deposition and other forms of pollution that affect the soil; this is especially true for sandy soils.
Best Time to Search
Based on previous collection records in Minnesota and Wisconsin that extend from 24 August to 25 October, the best time to search for L. trullisata is from late August through October. There is a 29 December record in Michigan.
Conservation Efforts in Minnesota
This species occurs in four protected sites: Helen Allison Savanna Scientific and Natural Area and Bunker Hills Regional Park on the Anoka Sand Plain, Minnesota Point Pine Forest Scientific and Natural Area in southern St. Louis County, and Sand Dunes State Forest in Sherburne County. In 1996, the Minnesota DNR funded a study to characterize the diversity and abundance of ectotrophic mycorrhizal fungi in old-growth and young northern hardwood-conifer forests. In 2007 and 2011 it funded a survey of macrofungi in western Minnesota and their molecular barcoding for improved identification. Ongoing surveys by University of Minnesota Bell Museum staff and students at State Parks and Scientific and Natural Areas have added to our knowledge as has the contributions of citizen scientists. Additional surveys are needed to search for other potential populations and to monitor the known locations of this species.
References and Additional Information
Barron, G. 1999. Mushrooms of Northeast North America: Midwest to New England. New edition. Lone Pine Publishing, Edmonton, Alberta and Vancouver, British Columbia, Canada; Auburn, Washington, U.S.A. 336 pp.
Malloch, D., and R. G. Thorn. 1985. The occurrence of ectomycorrhizae in some species of Cistaceae in North America. Canadian Journal of Botany 63:872-875.
Minnesota Biodiversity Atlas. 2013. Minnesota Biodiversity Atlas [web application]. Bell Museum, St. Paul, Minnesota. <http://bellatlas.umn.edu/collections/harvestparams.php>. Accessed 2013.
Mueller, G. M. 1992. Systematics of Laccaria (Agaricales) in the continental United States and Canada, with discussions on extralimital taxa and descriptions of extant types. Fieldiana Botany New Series 30:1-158.
MyCoPortal. 2018. Mycology Collections Portal [web application]. <http://mycoportal.org/portal/collections/>. Accessed 13 December 2018.
Redhead, S. A. 1989. A biogeographical overview of the Canadian mushroom flora. Canadian Journal of Botany 67:3003-3062.