Pearl moss

Plagiomnium cf. affine

Also known as Plagiomnium affine

FreshwaterMossRhizome divisionCuttings

Care at a glance

Light: Medium light
CO2: CO₂ beneficial
Temperature: 50–82°F; 10–28°C
Max height: 3.9 in; 10 cm

Growth rate: Slow
Placement: Epiphyte
Type: Moss
pH: 5.0–8.0
Hardness: 0–18 dGH
Spread: 3.9 in (10 cm)
Nutrient uptake: Water column
Growth region: Submersed or emersed
Difficulty: Medium
Family: Mniaceae
Origin: Unknown for the aquarium stock (shops name Europe or temperate Asia)

Overview

Pearl moss goes on wood or stone in small portions, tied with dark thread or glued, or tucked into crevices. It builds upright cushions up to about 10 cm tall. Give it medium light and CO2, which Dennerle doses at 20 to 30 mg/L. It grows without CO2, only more slowly. Its slow growth leaves it more prone to algae than faster mosses, so siphon debris out of the cushion. Buce Plant advises keeping the water below about 25 C to prevent browning. Rinse the gel off tissue culture portions, trim lightly, and split clumps to spread it.

In the wild

Pearl moss has no recorded wild origin. Shops trace it to Europe or temperate Asia, and most stock now comes from tissue culture labs such as Aquatic Farmer and Dennerle. Plagiomnium affine, the moss it resembles, grows on moist but not wet ground in woodland and turf across Europe and northern Asia. Pearl moss is a land moss that adapts to life underwater.

Good to know

Pearl moss is a true moss in the Mniaceae. The cf. in its name means compare with, since it looks like Plagiomnium affine but no specialist has confirmed the species. Each small, round leaf has a midrib running to the tip, and the leaves sit around upright or arching shoots like beads on a string. Leafy liverworts such as Solenostoma tetragonum carry their leaves in two flat rows, and their leaves lack a midrib. Pearl moss shows its midrib clearly, which rules out a liverwort.

Did you know

Several plants have sold as Pearl moss. In 2009 bryologist S. R. Gradstein identified the Pearl moss then sold in Europe as Heteroscyphus zollingeri, a leafy liverwort, and Tropica sells the liverwort Solenostoma tetragonum as Pearl Moss today. US shops use the name for this true moss.