Common Name: The Tree Mosses
Binomials: Climacium dendroides (Hedw.) Web. & Mohr, B. americanum Brid., and B. kindbergii (ren. & Card.) Grout
Habitat: Members of the Climaciaceae are typically found growing from exposed soil or humus, in swampy areas, i.e. wooded, mesotrophic, wetlands (1 & 2).
Range/Distribution: Tree mosses appear in many parts of the world, but as far as North America is concerned Climacium sps. can be found from the subarctic area of Alaska to northeastern Quebec, and south to Pennsylvania in the east and California in the west, more or less continuously (1). Climacium dendroides is typically found in the northern more parts of this distribution while Climacium americanum is typically found in the southern, mainland United States area (1). Climacium kindbergii is usually segregated to niches with a higher water level than the aforementioned two species (3).
Gametophyte Apperance: The tree mosses get their epithet from their dendroid growth, and tall stature, with respect to other mosses. Although at first appearing apocarpous, Climacium sps. actually grow by a subterranean rhizome-like primary stem, thus delimiting them to the pleurocarps (1). The dendroid and erect stems, which are most visible, are actually secondary stems and grow sympodially (1 & 2). These plants are typically dull green, but sometimes also yellow-brown in color (1). The leaves of the secondary stems are inserted in more than two rows, and are erect (1). The leaf cells of the Climaciaceae are neither pappilose nor mamillose, but smooth (1). There is abundant paraphyllia, which are small leaf like growths on the stem and may provide for additional photosynthetis activity (1 & 2). The leaves posses a single costa, broad at the base and narrowing towards the apex (1 & 2).
Sporophyte Apperance: Observing sporophytes of this family is often difficult as the Climaciaceae, particularly americanum, has been known to produce extensive clonal populations with ‘large’ geographical separation between female and male individuals (2). The sporophores arise from the secondary stems and the axils of branches and posses a long, erect setae,, which are sometimes clustered (1). The capsules are erect, smooth, cylindrical, and symmetric, and posses 16 peristome teeth (1). Climaciaceae produce spherical spores (1).
Noteworthy: Climacium kindbergii is sometimes considered simply a irregularly branched form of Climacium americanum caused by flooding. In other woods the first is merely an environmentally induced form of the second. However, when both are placed under uniform growing conditions, significant morphologically differences between the two remained (3). Genetic analysis of the two has shown differences between the two species, yet the two forms are virtually indistinguishable from one another (3).
1. Crum, H. 1983. Mosses: Mosses of the Great Lakes Forest 3rd Ed., University Herbarium, University of Michigan, Ann Arbor. Pgs. 3,4,11,12, 349, 350.
2. Shaw, A.J. & Goffinet, B. 2000. Bryophyte Biology, University Press, Cambridge. Pgs. 76,113,313,384.
3. Shaw, J. 1985. Experimental Taxonomy of Climacium americanum and Climacium kindbergii Preliminary Investigations. American Journal of Botany 72 (6) 6, Pg. 969.
Written by Chris Ference