Atrichum crispum (James) Sull.
Wave-leaved Crane's-bill Moss
Catharinea crispa, Atrichum laxifolium, Atrichum tortifolium
Basis for Listing
Atrichum crispum (wave-leaved crane’s-bill moss) is a disjunct species in the boreal bioclimatic zone, occurring only in Europe and eastern North America. It has been recorded regionally from Ontario, Iowa, Wisconsin, and the Upper Peninsula of Michigan. In Minnesota, only one population has been confirmed (Rice County; Minnesota and Northeast Iowa Morainal Section), hence there is not enough information available to detect a statewide population trend. Further survey work is needed to clarify the species’ abundance and distribution as well as the potential threats to its survival (Janssens 2005). Given its apparent rarity, Atrichum crispum was designated a species of special concern in 2013.
Atrichum crispum is yellowish-green to olive-green, with erect unbranched stems that are small to moderately robust (1.0-5.0 cm [0.4-2.0 in.] tall), often occurring in large mounds or patches (Smith Merrill and Ireland 2007; McKnight et al. 2013). When wet, the leaves are not undulate, wavy, or ruffled like most other Atrichum species; however, when dry, the leaves do fold upward and become shriveled and twisted, hence the specific epithet (crispum; Crum and Anderson 1981; McKnight et al. 2013). Leaves are ovate, 1.0 - 8.5 mm (0.04-0.33 in.) long, and 0.7 – 2.0 mm (0.03-0.08 in.) wide, tapering towards the leaf tip and near the stem attachment. The margins of the leaves consist of single small teeth that run from the tip to nearly the base. The costa (leaf midrib) ends slightly below the apex of the leaf. While many species in the Polytrichaceae family have distinct lamellae (green ridges or projections on the costa), A. crispum typically has only a few (0-3), which are inconspicuous and often interrupted along the length of the costa. In contrast to other Polytrichales in Minnesota, the leaves of Atrichum species also lack a differentiated sheath that wraps around the stem (Janssens 2014). As such, plants are often confused with sterile plants of Mnium or Plagiomnium; however, in the latter, creeping stems are often present within the colony of erect ones, and leaves are more egg-shaped, with a distinct sharp tip. With Mnium, teeth are in pairs along the margin and are smooth. In A. crispum, the leaf margins have distinct, though minute, papillae (small projections) that are visible under a microscope, which can be diagnostic (Ireland 1991). Capsules are cylindrical, upright to inclined, 1.0-3.5 mm (0.04-0.14 in.) long, with long-beaked calyptra (lids). Setae (stalk supporting the capsule) are 0.5-3.0 cm (0.2-1.2 in.) long (Smith Merrill and Ireland 2007; McKnight et al. 2013).
The species grows as a colonist on wet soils in woods and seepage fens and has also been reported to occur on wet and sandy or peaty soils along streams or rivers, along roadside ditches in shady woods, and on margins of swamps, though it is probably limited to calcareous or somewhat acidic habitats. In Minnesota, it has been found on peat in a hummocky calcareous seepage fen at the edge of an upland.
Biology / Life History
This species is dioicous (male and female reproductive organs on separate plants), with male and female plants approximately equal in size. Capsules mature in June.
Conservation / Management
If Atrichum crispum's habitat in Minnesota is determined to be restricted to calcareous fens, where calcium-rich groundwater supports continuous peat development, then continued attention to impacts to these fens will need to be monitored. Calcareous seepage fens are highly susceptible to disturbance; reduction in the normal supply of groundwater results in oxidtion of the surface peat, releasing nutrients and fostering the growth of competing vegetation. Furthermore, A. crispum is at the edge of its North American range here in Minnesota. With climate change and the potential loss of moist calcarous habitat conditions, this species' viability in the state could be at risk.
Best Time to Search
The best time to search for A. crispum is from May through September or essentially anytime the ground is not covered by snow.
Erika R. Rowe (MNDNR), 2018
(Note: all content ©MNDNR)
References and Additional Information
Crum, H. A., and L. E. Anderson. 1981. Mosses of eastern North America. In two volumes. Columbia University Press, New York, Yew York. 1330 pp.
Flora of North America Editorial Committee, editors. 2007. Flora of North America north of Mexico. Volume 27, Bryophytes: Mosses, Part 1. Oxford University Press, New York, New York. 734 pp.
Ireland, R. R. 1991. Cuticular papillae of Atrichum crispum. The Bryologist 94(1):73-76.
Janssens, J. A. 2001. Bryophyte survey of the Cannon River Wilderness Area County Park calcareous fen site, Rice County, Minnesota. Report to the Minnesota Department of Natural Resources, Division of Waters. 5 pp.
Janssens, J. A. 2001. Bryophyte survey of the Pheasants Forever calcareous fen site, Dodge County, Minnesota. Report to the Minnesota Department of Natural Resources, Division of Waters, St. Paul. 5 pp.
Janssens, J. A. 2001. Bryophyte survey of the Stewartville calcareous fen site, Olmsted County, Minnesota. Report to the Minnesota Department of Natural Resources, Division of Waters. 5 pp.
Janssens, J. A. 2001. Bryophyte survey of the Sucker Creek calcareous fen site, Meeker County, Minnesota. Report to the Minnesota Department of Natural Resources, Division of Waters, St. Paul. 5 pp.
Janssens, J. A. 2002. Bryophyte survey of the Perched Valley calcareous fen, Goodhue County, Minnesota. Report to the Minnesota Department of Natural Resources, Division of Waters. 4 pp.
Janssens, J. A. 2005. Proposed candidates of endangered, threatened, and special concern species of bryophytes for Minnesota: update June 2005. Report to the Minnesota Department of Natural Resoucres, County Biological Survey, St. Paul. 18 pp.
Janssens, J. A. 2009. MS Access database on Minnesota bryophytes. Lambda-Max Ecological Research, Minneapolis, Minnesota.
Janssens, J. A. 2014. Noteworthy mosses and liverworts of Minnesota. Part II: Species fact sheets. Minnesota Department of Natural Resources. 208 pp.
Janssens, J. A. 2016. Illustrated bryophyte flora of Minnesota 2 - Andreaeaceae, Buxbaumiaceae, Diphysciaceae, Emcaluptaceae, Funariaceae, Polytrichaceae, Tetraphidaceae, Timmiaceae: based on the flora of North America, Volume 27, limited to the species occurring in Minnesota, and illustrated by Joannes A. Janssesn. Minnesota Department of Natural Resources, St. Paul.
McKnight, K. B., J. R. Rohrer, K. McKnight-Ward, and W. J. Perdrizet. 2013. Common mosses of the Northeast and Appalachians. Princeton University Press, Princeton, New Jersey. 392 pp.
Minnesota Department of Natural Resources. 2005. Field guide to the native plant communities of Minnesota: the eastern broadleaf forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 394 pp.
NatureServe. 2009. NatureServe Explorer: an online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. <http.//www.natureserve.org/explorer>. Accessed 10 June 2009.
Smith Merrill, G. L., and R. R. Ireland. 2007. Polytirchaceae. Pages 121-161 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 27, Bryophytes: Mosses, Part 1. Oxford University Press, New York, New York.