Which of the following is responsible for peat formation?
A. Riccia
B. Sphagnum
C. Funaria
D. Marchantia

The correct answer is: Sphagnum. Sphagnum (peat moss) is responsible for peat formation because it grows in waterlogged, acidic bogs, retains vast amounts of water, slows decay, and its dead layers accumulate over time to form peat. Riccia, Funaria, and Marchantia do not create such thick, preserved deposits in the same way.

• Correct option: B. Sphagnum.

Why: Sphagnum’s unique biology creates acidic, low‑oxygen, waterlogged conditions that prevent complete decay, so dead plant material builds up as peat.

What is peat?

Peat is an accumulation of partially decayed plant material that forms in wetlands (bogs, mires) where waterlogging keeps oxygen low and decomposition very slow. Over centuries to millennia, this plant matter builds up into thick layers called peat deposits.
Peatlands are often dominated by mosses and shrubs, with Sphagnum being a major component; its traits help create and maintain the bog environment that enables peat to form.

Why Sphagnum forms peat?

Sphagnum moss acts like an ecosystem engineer: it holds 16–26 times its dry weight in water, acidifies its surroundings by exchanging cations for hydrogen ions, and contains phenolic compounds that resist decay. These features make the habitat consistently wet, acidic, and low in oxygen, sharply slowing microbial breakdown and allowing peat to accumulate.
As Sphagnum grows at the surface, older lower layers die but do not fully decompose; over time, this creates thick peat layers that can reach many meters in depth under suitable conditions.

Why not Riccia, Funaria, Marchantia?

• Riccia and Marchantia are liverworts found in moist places, but they do not typically engineer large, acidic, anoxic bog systems that build extensive peat deposits.
• Funaria is a moss (often called cord moss) found in damp soils, but it is not the “peat moss” and does not drive large-scale peat accumulation like Sphagnum does.