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

Species description:
Genus name referring to the strong midrib of the leaf. Species name derived from the tendency of the plants to accumulate lime and form tufa that encrusts them.

Reproduction:
Sporophytes infrequent, sporangia curved-cylindric, seta elongate, appearing in summer; plants somewhat brittle, the frag­ments serving for vegetative reproduction.

Comments:
This species accumulates lime in hot-spring areas and also in some cold springs. Indeed, sometimes whole plants become encrusted and "petrified" with lime (tufa). Sometimes treated as Palustriella commutata.

Distinguishing characteristics:
This species, except on microscopic charac­ters, closely resembles some species of Drepanocladus that grow in the same habitat. Microscopic examination, however, will expose the paraphyllia on the stem; these are absent in Drepanocladus. Paraphyllia are short, branched, hair-like structures on the stem, among the leaf bases. These can be seen on moist (not wet) material with a lOx hand lens. The leaves are markedly pleated, a feature shared by few mosses in this wet habitat.

Habit:
Forming turf-like mats of rich green to rusty, brownish-green to golden green; plants sometimes accumulating tufa; from sea level to subalpine elevations.

Similar Species:
Besides Drepanocladus, C. commutatum superficially re­sembles some species of Hypnum, but Hypnum has a double and obscure midrib, rather than a single obvious one, as in Cratoneuron. The pleated leaves and paraphyllia also separate Cratoneuron from Drepanocladus and Hypnum.