Rare Species Guide

 Jaffueliobryum wrightii    (Sull. in Gray) Ther.

Wright's Blunt Leaved True Moss 

MN Status:
special concern
Federal Status:


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Minnesota range map
Map Interpretation
North American range map
Map Interpretation


Coscinodon wrightii, Grimmia wrightii

  Basis for Listing

Jaffueliobryum wrightii (Wright’s blunt leaved true moss) is endemic to eastern North America, within the temperate bioclimatic zone. It has been recorded regionally from Ontario, North and South Dakota, Nebraska, Iowa, and Wisconsin. In Minnesota, only three populations have been found, one in Le Sueur County (Big Woods), one in Winona and one in Goodhue counties (The Blufflands). Jaffueliobryum wrightii grows as a colonist in dry saxicolous (growing among rocks) habitat. With only three populations documented in Minnesota, there is too little information available at this time to detect a statewide population trend. Further inventory work is needed to clarify the species’ distribution in the state as well as potential threats to its survival. Based on its apparent rarity, Jaffueliobryum wrightii was designated a special concern species in 2013.


Jaffueliobryum wrightii is a yellow-green to dark olive-green moss that grows as fragile hoary dense cushions or turfs, 5-15 mm (0.2-0.6 in.) high. Stems are sparsely branched and julaceous (appearing smoothly cylindric) due to the crowded and overlapping leaves. Leaves are flat (not keeled) to concave-incurved, with a rounded-obtuse apex that transitions to a long awn of variable length, though typically longer than the leaf blade (Hastings and Ochyra 2007; Janssens 2016). Awns (up to 2 mm [0.8 in.]) are hyaline and smooth to finely serrulate. Costa (midrib) ends below the base of the awn. Setae (stalks) are 0.2-0.4 mm (0.008-0.016 in.) and support an ovoid yellow-brown capsule (0.7-1.0 mm [0.03-0.04 in.]) that turns red-brown with age (Hastings and Ochyra 2007). Capsules are often completely covered or hidden by the tips of the leaves or awns. Jaffueliobryum wrightii may be confused with J. raui (Jaffueliobryum moss), which also occurs in southeast Minnesota. However, with J. raui, leaves are distinctly keeled and proximal, stem leaves are mostly spreading; whereas, with J. wrightii, proximal stem leaves are mostly appressed, and leaves are not keeled (Janssens 2016).


Across its range, J. wrightii is widespread and locally common on dry sandstone or limestone rock (rarely metamorphic rock) in open arid to semi-arid shrub woodland communities and grasslands (Hastings and Ochyra 2007). In Minnesota, it has been found growing on exposed sandstone on both outcrops and cliffs.

  Biology / Life History

Jaffueliobryum wrightii is an autoicous (male and female reproductive organs in separate inflorescences on the same plant) species.

  Conservation / Management

Because Jaffueliobryum wrightii has been found growing on sandstone outcrops and is a somewhat fragile species (being easily removed from its substrate), it may be particularly sensitive to climbing or trampling. Hiking, climbing, or even biking across exposed rock with shallow soil could damage populations.

  Best Time to Search

Spores mature spring-summer; however, the best time to search for J. wrightii 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.

Hastings, I. R., and R. Ochyra. 2007. Grimmiaceae. Pages 204-305 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 27. Oxford University Press, New York, New York.

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 Resources, 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. 2016. Illustrated bryophyte flora of Minnesota 3 - Archidaceae, Bryoxiphiaceae, Grimmiaceae, Seligeraceae: based on the flora of North America, Volume 27, limited to the species occurring in Minnesota, and illustrated by Joannes A. Janssens.

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.

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