Calliergon giganteum (Schimp.) Kindb.
giant water-moss (giant calliergon moss)

Species Account Author: Wilf Schofield
Extracted from Some Common Mosses of BC

Introduction to the Bryophytes of BC


© Bryan Kelly-McArthur     (Photo ID #87176)


E-Flora BC Static Map

Distribution of Calliergon giganteum
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Species Information

Species description:
Genus name meaning "beautiful form" is reference to the frequently tidy branching and attractive appearance of the leafy plants. The species name denoting the very large plants that, in floating mats, can reach lengths of 350 mm or more.
Sporophytes infrequent; seta red, smooth, twisted when dry; sporangium reddish-brown when mature, smooth but not glossy; peristome teeth yellow-brown.
Distinguishing characteristics:
The regularly pinnate plants with blunt-­tipped leaves bearing a midrib, associated with the wet habitat in cal­careous substrata, are usually reliable features. Swollen alar cells are usually visible with a hand lens.
Forming dense or loose mats of suberect to erect interwoven shoots that vary from light to dark green to often tinged with yellow or brown; plants often stiff and accumulating white coatings of calcium carbonate.
Similar Species:
C. giganteum can be distinguished from Calliergonella cuspidata by its obscure midrib; the midrib in Caltiergon is distinct. C. cordifo/ium is similar but usually little-branched and the alar cells are not obvious or swollen as is evident in C. giganteum. C. sarmentosum is usually wine-red, irregularly branched and mainly alpine or subalpine. P/eurozium schreberi has two midribs and is generally a terrestrial species of dry habitats; swollen alar cells are absent and the stems are red-­brown (in C. giganteum they are green to brown).


If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Illustration SourceSome Common Mosses of BC

Habitat and Range

Sometimes locally abundant, especially in northern and inte­rior localities in wet depressions, lakeshores, pond margins and wet­land in calcareous terrain, sometimes forming floating mats; rare near sea level, extending to subalpine elevations, usually in non-forested sites but sometimes margined by forest
World Distribution

Circumboreal in the Northern Hemisphere, extending northward in arctic latitudes; in North America extending southward, in the east to Pennsylvania and in the west to Colorado.


Synonyms and Alternate Names:
Calliergon giganteum (Mik.) Karcz.
Calliergon giganteum (Mik.) Karcz.
Calliergon giganteum var. cyclophyllotum
Calliergon giganteum var. dendroides
Calliergon giganteum var. fluitans
Calliergon giganteum var. hystricosum G. Roth & Bock in G. Roth
Calliergon giganteum var. immersum Ruthe ex Karcz.
Calliergon giganteum var. labradorense (Ren. & Card.) Grout
Calliergon giganteum var. pennatum Karcz.
Calliergon giganteum var. tenue Karcz.
Calliergon subsarmentosum Kindb. sensu Rev. Bryol. 36: 42. 1909