Arrhenopterum heterostichum    Hedwig

Differential Branched Crease Capsule Moss 

MN Status:
special concern
(as Aulacomnium heterostichum)
Federal Status:


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Minnesota range map
Map Interpretation
North American range map
Map Interpretation


Aulacomnium heterostichum

  Basis for Listing

Aulacomnium heterostichum (differential branched crease capsule moss) has a discontinuous range in the temperate bioclimatic zone, presently occurring largely in eastern North America and Japan. It has been recorded regionally from Ontario, Iowa, and Wisconsin. In Minnesota, only two populations have been documented, both in The Blufflands of Winona County. Although there is too little information available to detect a statewide population trend at this time (Janssens 2005), with only two populations confirmed in the state, A. heterostichum was designated a special concern species in 2013.


This moss grows in shady places, forming small loose mats that are glossy distally when dry but overall have a green or sometimes yellow-brown appearance due to the yellow or reddish brown stems. Erect stems, 2.0-4.0 cm (0.8-1.6 in.) high, can be unbranched or densely forked, with conspicuous reddish-brown rhizoids, particularly near the base. Leaves are tissue-paper thin and do not change considerably when dry, except for appearing slightly crumpled. The leaves typically angle outward 45 degrees from either side of the stem, giving shoots a flattened appearance (McKnight et al. 2013). Leaf shape is oblong-ovate, 2.0-3.5 mm (0.8-1.4 in.) long, with leaves at the stem apex longer and more tongue-shaped. Costa (midrib) is prominent and occasionally flexuose (twisted or wavy), ending just below the leaf tip. Margins are coarsely serrate in the upper half and often narrowly revolute below. Capsules are slender, 3.0-5.0 mm (0.12-0.20 in.) long, on setae that are 8.0-17.0 mm (0.31-0.67 in.) long.


Throughout its range, A. heterostichum mostly occurs on soil in dry to moist woods, especially oak forests and occasionally on humid soils on the slopes of ravines or on bark at the base of trees. In Minnesota, it has only been found in the southeast in fire-dependent oak woodlands (southern dry-mesic oak-hickory woodland) or in mesic hardwood forests with a large oak component (southern mesic oak-basswood forest and southern dry-mesic oak forest).

  Biology / Life History

Aulacomnium heterostichum is distinct when compared to other members of this genus and is often found in drier environments. It has been reported that plants occasionally produce small leaf-like brood bodies that can grow on an extension of the stem and its tip (Lowry and Steere 1949). These small bodies can each grow an entire new plant, if they fall off and find the right environment.

  Conservation / Management

Anything that would remove or open the canopy of woodlands and mesic forests that have a significant oak component could be damaging to this species by altering the temperature and humidity of its habitat. Likewise, anything that would significantly impact the ground layer on which it grows must also be avoided. Further inventory work is needed to clarify the species’ abundance and distribution in the state as well as the potential threats to its survival (Janssens 2005).

  Best Time to Search

The best time to search for Aeterostichum 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.

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. P., D. G. Horton, and J. F. Basinger. 1979. Aulacomnium heterostichoides sp. nov., an Eocene moss from south central British Columbia. Canadian Journal of Botany 57(20):2150-2161.

Miller, N. G. 2007. Aulacomniaceae in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 28 [web application]. <>. Accessed 19 September 2016.

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.//>. Accessed 10 June 2009.

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