Two-ranked moss

Pseudotaxiphyllum distichaceum (Mitt.) Iwats.

Pseudotaxiphyllum distichaceum
Sue Williams

State Protection
Not Listed
Not listed or protected by New York State.
Federal Protection
Not Listed
State Conservation Status Rank
Imperiled or Vulnerable in New York - Very vulnerable, or vulnerable, to disappearing from New York, due to rarity or other factors; typically 6 to 80 populations or locations in New York, few individuals, restricted range, few remaining acres (or miles of stream), and/or recent and widespread declines. More information is needed to assign either S2 or S3.
Global Conservation Status Rank
Apparently or Demonstrably Secure globally - Uncommon to common in the world, but not rare; usually widespread, but may be rare in some parts of its range; possibly some cause for long-term concern due to declines or other factors. More information is needed to assign either G4 or G5.


Did you know?

The name 'distichaceum' refers to a flattened and seemingly 2-ranked arrangement of leaves. The species was first collected in Nepal and the northeastern Himalayas.

State Ranking Justification

There are 15 known locations for this moss in the state. Thirteen older specimens were verified as part of the update to the rare moss list of New York (Cleavitt et al. 2006). Several new sites were identified as a part of that project in Dutchess, Ulster and Warren Counties. In 2009, a few new sites were located in the southwestern Catskills. Easily overlooked and similar to other species, further surveys should turn up more locations for this moss.

Short-term Trends

The trend seems stable for most populations.

Long-term Trends

It is hard to say what the long term trend is because many moss populations haven't been studied. However, given the current status of this particular bryophyte, the long term trend seems stable.

Conservation and Management


There are no known threats at this time. Pseudotaxiphyllum distichaceum can be found in a variety of habitats, from forests to cliffs and ledges. Because it is easy to mistake for other more common species, it is probably overlooked and may not be as rare as it seems. The species was found at two of three random roadside ledge sites, which has been interpreted as strong evidence that it has been undercollected in the state (Cleavitt et al. 2006).

Conservation Strategies and Management Practices

There are no management needs at this time.



It is often found on moist soil of banks in woods, on the underside of ledges or in crevices as well as on moist cliffs of acid rock (Crum & Anderson 1981). Base of ledges (Cleavitt 195, NYBG). On wet boulders in woods (Ireland 1982).

Associated Ecological Communities

  • Beech-maple mesic forest (guide)
    A hardwood forest with sugar maple and American beech codominant. This is a broadly defined community type with several variants. These forests occur on moist, well-drained, usually acid soils. Common associates are yellow birch, white ash, hop hornbeam, and red maple.
  • Maple-basswood rich mesic forest (guide)
    A species rich hardwood forest that typically occurs on well-drained, moist soils of circumneutral pH. Rich herbs are predominant in the ground layer and are usually correlated with calcareous bedrock, although bedrock does not have to be exposed. The dominant trees are sugar maple, basswood, and white ash.
  • Rich mesophytic forest (guide)
    A hardwood or mixed forest that resembles the mixed mesophytic forests of the Allegheny Plateau south of New York but is less diverse. It occurs on rich, fine-textured, well-drained soils that are favorable for the dominance of a wide variety of tree species. A canopy with a relatively large number of codominant trees characterizes this forest. Canopy codominants include five or more of the following species: red oak, red maple, white ash, American beech, sugar maple, black cherry, cucumber tree, and black birch.

Associated Species

  • Atrichum altecristatum
  • Atrichum angustatum
  • Calypogeia
  • Dicranella heteromalla
  • Dicranum scoparium
  • Isopterygium elegans
  • Plagiomnium cuspidatum
  • Plagiothecium denticulatum
  • Thuidium delicatulum


New York State Distribution

Pseudotaxiphyllum distichaceum occurs from the Adirondacks south to the Catskills. New York is close to the northern edge of its range.

Global Distribution

Pseudotaxiphyllum distichaceum occurs in North America from Maine to South Carolina and west to Michigan, Wisconsin, Illinois, Missouri and Arkansas; in Ontario and Nova Scotia; Central and South America; the Himalayan mountains; and Japan.

Identification Comments

General Description

Pseudotaxiphyllum distichaceum , a moderately small moss, grows in shiny, flat mats on the bare soil of brook banks, trail edges, cliff crevices and bases of cliffs in wooded areas. Small brood branches are common and often clumped at the tips of branches. The leaves are wide-spreading and very flattened; they are somewhat undulate above and secund at the tips when dry.

Identifying Characteristics

A moss with few distinguishing characteristics, Pseudotaxiphyllum distichaceum has many overlapping flattened branches. Because of this flattening, the leaves appear to be in two rows. This moss almost always has brood branches clustered at the tip of the branches, easily seen with a handlens. These brood branches are short to elongate and end in a cluster of 1-5 leaf primordia. Under the microscope, its leaves are often asymmetric, somewhat toothy at the tips, never curved downwards, with longish, smooth cells, and with undifferentiated alar cells. It is never seen with capsules.

Best Life Stage for Proper Identification

Pseudotaxiphyllum distichaceum can be identified when brood branches are present.

Similar Species

Pseudotaxiphyllum elegans is quite similar but both the location and the structure of its brood branches are different from those of P. distichaceum. In P. elegans, brood branches are usually found along the length of the branches instead of clumped at the end, and its brood branches are more like copies of the parent plant, bearing reduced leaves throughout instead of clustered at the tip. In P. elegans, the leaves are more symmetric as well and are not usually undulate. The species of the genus Plagiothecium are also similar; they are also flattened mosses growing in mats in similar habitats. These mosses do not have brood branches like Pseudotaxiphyllum species, although sometimes they can have cylindrical brood bodies in the leaf axils. All Plagiotheciums have leaves that curve downward and their leaves are usually without teeth.

Best Time to See

Like most bryophytes, this species can be seen in good condition any time of the year.

  • Vegetative

The time of year you would expect to find Two-ranked moss vegetative in New York.

Two-ranked moss Images


Two-ranked moss
Pseudotaxiphyllum distichaceum (Mitt.) Iwats.

  • Kingdom Plantae
    • Phylum Bryophyta
      • Class Bryopsida
        • Order Hypnales
          • Family Hypnaceae


  • Isopterygium distichaceum (Mitt.) Jaeg.
  • Isopterygium subfalcatum (Austin) A. Jaeger
  • Plagiothecium subfalcatum Austin
  • Stereodon distichaceus Mitt.
  • Taxiphyllum howellianum H.A. Crum & L.E. Anderson

Additional Resources

Best Identification Reference

Ireland, R. R. 2003. Pseudotaxiphyllum, in Bryophyte Flora of North America, Provisional Publication. Buffalo Museum of Science. August 2007. <>. Date viewed March 17, 2009.

Other References

Anderson, L.E., H.A. Crum, and W.R. Buck. 1990. List of the mosses of North America north of Mexico. The Bryologist 93(4):448-499.

Cleavitt, N. L, S. A. Williams, and N.G. Slack. 2006. Relationship of Bryophyte Occurrence to Rock Type in Upstate New York and Coastal Maine. Final report for the Biodiversity Research Institute. New York State Museum, Albany, NY

Cleavitt, N.L., S.A. Williams, and N. Slack. 2006. Updating the rare moss list for New York State: Ecological community and species-centered approaches. Final report for the Biodiversity Research Institute. New York State Museum. Albany, NY.

Corey, Michael. 1991. Moss notes from Mohonk Preserve. New York Rare Bryophyte Newsletter 2: 3-4.

Crum, Howard A. and Lewis E. Anderson. 1981. Mosses of eastern North America. 2 vol. Columbia University Press, New York. 1328 pp.

Ireland, R.R. 1982. Moss flora of the Maritime Provinces. National Museums of Canada, Publications in Botany 13.

Ketchledge E.H., 1980. Revised checklist of the mosses of New York State. New York State Museum Bulletin 440.

Leonardi, Lorinda. 1996. Pseudotaxiphyllum distichaceum (Mitt.) Iwats. [Isopterygium distichaceum (Mitt.) Jaeg.]. New York Rare Bryophyte Newsletter 4: 1-3.

New York Natural Heritage Program. 2024. New York Natural Heritage Program Databases. Albany, NY.

Town, William R., Michael Corey, and M. Pudiak. 1994. A preliminary report of the moss flora of the northern Shawangunk Mountains of Ulster County, New York. Evansia 11(1): 22-27.


About This Guide

Information for this guide was last updated on: April 27, 2009

Please cite this page as:
New York Natural Heritage Program. 2024. Online Conservation Guide for Pseudotaxiphyllum distichaceum. Available from: Accessed April 16, 2024.