Lysurus cruciatus (Lebr. & Mont.) Lloyd
Basis for Listing
Lysurus cruciatus (lizard’s claw) is a very distinctive species that has been collected from only a single site in Minnesota, a pasture in Washington County (St. Paul-Baldwin Plains and Moraines Subsection of the Eastern Broadleaf Forest Province). It grows on soil in pastures associated with undecomposed horse manure. It has been reported from the eastern U.S. (New York and New Jersey to Pennsylvania and Ohio), through the Midwest to Colorado, California, Washington, and southern Canada (Quebec and British Columbia). It has also been reported from South America, South Africa, and Australia. It is widespread but uncommon and is only infrequently reported. It has been suggested that it may be introduced in North America and also in Europe (Ginns 1977). In Minnesota, it is at the northern edge of its range. Its ecology is unstudied and population sizes seem to be small. Lysurus cruciatus was listed as a special concern species in Minnesota in 1996.
The fruiting body of L. cruciatus emerges from a white egg-like structure, up to 3 cm (1.2 in.) tall by 2.5 cm (0.98 in.) wide, that forms a cup around the base of the stalk. The stalk bears a cap, 2.5 cm (0.98 in.) long by 2 to 2.5 cm (0.79-0.98 in.) wide, consisting of 6 to 7 arms that are closely appressed at first but open or spread outward somewhat at maturity. The inside of the arms are brownish-orange and bear the slimy and fetid chocolate brown spore mass that gives this group of mushrooms its common name, stinkhorns. The stalk is white, porous, and up to 9 cm (3.5 in.) long by 2.5 cm (0.98 in.) wide. Spores are elliptical, 4 - 4.5 by 1.5 - 2 µm, and pale green. Lysurus cruciatus can be confused with L mokusin (small lizard’s claw), which has red arms bearing the brown to black spores. In L mokusin the arms are typically joined at the tips to form a tapering spire, and the stalk is fluted and 4- to 6-angled in cross section, while in L. cruciatus it is round (Miller and Miller 2006; Smith et al. 1981).
Besides its occurrence in pastures near undecomposed horse manure, it has been reported on humus and woody debris (Smith et al. 1981).
Biology / Life History
Spores are distributed by flies and beetles, which are attracted to the strong, fetid odor. Reports of its appearance in flower beds, heavily fertilized gardens, greenhouses, and pastures with fresh manure (Ginns 1977) suggest that increased soil nutrients may favor its occurrence.
Conservation / Management
Lysurus cruciatus has been collected in Minnesota in September and October. It is reported to fruit in spring, summer, and fall during cool, wet periods (Miller and Miller 2006).
Conservation Efforts in Minnesota
Assessing the presence of L. cruciatus in Minnesota will require enlisting the assistance of citizen scientists as its fruiting is erratic. Whether efforts to conserve it ought to be considered requires a better understanding of its biology and origins.