E-Flora BC: Electronic Atlas of the Flora of British Columbia

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.

Reproduction:
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.

Habit:
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).