Pellia Liverwort

About

Monosolenium tenerum is a thalloid liverwort - not a moss, not a fern - and almost every shop label on it is wrong. Grown properly it is unmistakable: a dark, glossy, faintly translucent green cushion of repeatedly forked ribbons piled 3-5 cm deep on a stone or straight on the substrate, the individual thalli broadening towards a centimetre across. That width is the whole tell, and it is not free. Under weak light and thin water the new growth comes back stretched and narrow instead - 2-3 cm long but only 3-5 mm wide, the state Claus Christensen simply calls less decorative - and the cushion stops reading as a cushion. Pearling is on the same conditional: it is under plenty of light and added CO2 that tiny oxygen bubbles collect in the rhizoids on the underside, and without both you will not see them. The everyday failure, though, is mechanical. The tissue is famously brittle, a clump falls apart in the bag on the way home, and every loose crumb keeps growing wherever the flow parks it - Flowgrow calls the loosely growing plant a veritable pest, and this is how a tidy tank ends up with green pads wedged in every crevice. A slower failure is dirt: the dense interior, sitting in the gentle flow this plant wants, silts up with detritus, and stopping that is half of why Dennerle tells you to keep trimming. Colour is not the variable here - light, CO2 and iron buy thallus width and cushion density, never a hue change, and the plant stays the same deep green in soft water and hard, dosed and undosed. Two lookalikes matter in the shop. Riccia fluitans, already in this catalogue, is this plant shrunk tenfold, and the decisive test is buoyancy: Monosolenium is heavier than water and settles on the bottom by itself, while Riccia floats and has to be held down under mesh or line. Suesswassertang, the fern prothallium (Lomariopsis lineata) sold from the same fridge, has thinner, irregular, lettuce-like lobes instead of this plant's regular repeated forking. And the name: Pellia endiviifolia is a different liverwort, filed as an erroneous name by every database that carries this plant, so a cup labelled Pellia is this one.

Care

It does not attach for you. There are rhizoids on the underside, but Christensen is blunt that they anchor poorly under water, so tie a clump on with nylon line, pin it under a hairnet or mesh, or scatter small sprays among Eleocharis until its own weight and the surrounding stems hold it. 18-26 C, pH 5-7, soft water or hard. How much light it needs is genuinely contested - Tropica rates the demand low, Aquasabi medium, Flowgrow medium to high - and the honest reading is that it survives at the low end but only earns the wide-thallus cushion at the high end, with CO2. Keep flow low, handle it as little as you can, and trim before the cushion is more than a few centimetres thick: an untrimmed one shades out its own base, which dies off and lets the whole clump float up, and its packed interior traps detritus that has to be cut out or blown clear.

Diet

Rootless, so everything comes from the water column: feed the water rather than the substrate - NO3 10-50, PO4 0.1-3, K 5-30 and Fe 0.01-0.5 mg/l covers it, and it does want adequate phosphate rather than the starved levels a carpet tank is often run at. The dense interior grows biofilm that shrimp graze without harming the plant, which is why it is such a good shrimp and fry cushion, but large herbivores and boisterous diggers simply tear the brittle thalli apart.

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Frequently asked questions

What water parameters does a Pellia Liverwort need?

Pellia Liverwort does best at 10–30 °C (50–86 °F), pH 5–8 and a general hardness of 0–30 °dGH.

Where should Pellia Liverwort be placed in the aquarium?

Pellia Liverwort works best attached to wood or rock, not planted in the substrate and reaches around 5 cm.

Is the Pellia Liverwort suitable for beginners?

Yes — Pellia Liverwort is one of the easier species to keep and forgives typical first-tank mistakes, as long as the aquarium is cycled and maintained.

Sources

• Flowgrow Wasserpflanzen-Datenbank - Monosolenium tenerum (Zartes Lebermoos)
• Flowgrow Aquatic Plant Database - Monosolenium tenerum (English mirror)
• Tropica Aquarium Plants - Monosolenium tenerum (002C TC)
• Aquasabi - Monosolenium tenerum
• Dennerle Plants UK - Monosolenium tenerum (Pellia)
• Claus Christensen (Tropica) - Monosolenium tenerum, The Aquatic Gardener
• Monosolenium - English Wikipedia (family and monotypy)
• Vikipedija - Kerpsamanės (Marchantiopsida), source of the Lithuanian group word