Schedonnardus paniculatus (Nutt.) Trel.
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Basis for Listing
Schedonnardus paniculatus is one of a small handful of rare plants that occur on outcrops of Sioux quartzite and crystalline bedrock in the southwestern corner of the state. This is a rare habitat type that harbors a number of very specialized plant species, a high proportion of which are considered endangered, threatened, or special concern in the state. By and large, the prairie habitat that originally surrounded the outcrops has long since been plowed and planted to agricultural crops, or fenced and converted to pasture. The vegetation on the outcrops has survived, to the extent that it has, because there was no practical way to exploit the rock. But that may be changing now. A market is developing for gravel made from the rock, and the high prices paid for crops is leading some farmers to seriously consider blasting or quarrying the rock to make room for more crop fields. Schedonnardus paniculatus was listed as a special concern species in Minnesota in 1984.
Schedonnardus is a monotypic (single species) North American genus in the tribe Cynodonteae. The only species is S. paniculatus, a perennial with short, tangled stems 8-55 cm (3.1-21.7 in.) tall. The leaves are mostly basal and have compressed-keeled sheaths. The ligule of the leaf is 1-3.5 mm (0.04-0.14 in.) long and membranous. The blade is 1-12 cm (0.4-4.7 in.) long, 0.7-2 mm (0.03-0.08 in.) wide, stiff, usually folded, and often twisted. Useful characters to observe are the thick, white margins on the leaf blade and the well-developed midrib.
Schedonnardus paniculatus is a characteristic plant of dry prairies on the Great Plains, but suitable natural habitats in Minnesota seem to be limited to southern bedrock outcrops of Sioux quartzite bedrock, and less often crystalline bedrock, in the southwest corner of the state. This coincides very closely with habitats reported in adjacent portions of Iowa (Pohl 1966). The native vegetation on the outcrops is sparse and consists of a combination of dry prairie species and outcrop specialists. The plants tend to occur in cracks and crevices of the outcrops where wind-blown soil accumulates, and at the edges of the outcrops where the soil is thin and patchy. Schedonnardus paniculatus may also colonize some dry, disturbed soils in southwest Minnesota, but how often this occurs and how persistent such colonies are, is unknown.
Biology / Life History
Schedonnardus paniculatus is a wind-pollinated and wind-dispersed perennial. When ripe, the seed-bearing panicle breaks off at the base and tumbles in the wind, releasing seeds along the way (Snow 2003). The species is considered exceptionally good at exploiting marginal soils and gaps in vegetation where competition from other species is reduced - a quality that seems pre-adapted to surviving the harsh conditions found on exposed bedrock.
Conservation / Management
In many ways, S. paniculatus will thrive with little or no active management. It is adapted to prairie wildfires, but probably does not need fire, and it apparently survives a certain amount of cattle grazing and broad-leaved herbicide. However, the rare associates that frequently occur with S. paniculatus are not so hardy, particularly the aquatic species that occur in temporary rainwater pools on the same outcrops including Limosella aquatica (mudwort), Isoetes melanopoda (prairie quillwort), Crassula aquatica (pigmyweed), and Marsilea vestita (hairy waterclover). Two other rare species, Opuntia macrorhiza (plains prickly pear) and Buchloe dactyloides (buffalo grass), are also associated with the terrestrial components of S. paniculatus habitat. For the sake of these more sensitive species, cattle grazing should be avoided or limited to low stocking rates. Herbicide use should be avoided altogether.
Conservation Efforts in Minnesota
Schedonnardus paniculatus is known to occur in one county park, one State Park, one national monument, and one site owned by the Minnesota Historical Society. However, the current extent and condition of these populations is not known.
Pohl, R. W. 1966. The grasses of Iowa. Iowa State Journal of Science 40:341-566.
Snow, N. 2003. Schedonnardus. Pages 228-230 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 25. Oxford University Press, New York, New York.