Marchantia quadrata is a species of liverwort, a simple non-flowering plant that grows as a flat, green, leaf-like structure (thallus) typically found on damp rocks and soil along stream banks in the Northern Hemisphere.

Like most liverworts, it reproduces both sexually, through separate male and female plants that produce umbrella-like reproductive structures, and through regeneration from fragments.

The thallus is pale green with somewhat wavy margins, and branches dichotomously when young, later forming apical innovations.

The ventral surface bears two longitudinal rows of purple scales along the median line, and both smooth and pegged rhizoids.

[6] The thallus contains specialised sclerotic cells in its ventral region that serve as conducting tissue, though these differ from true tracheids in both form and function.

The species demonstrates significant regenerative capabilities, readily producing adventitious growths from its ventral cells under suitable conditions.

The species shows less adaptation to hydrophytic (aquatic) conditions during early development compared to M. polymorpha, reflecting its more strictly mesophytic adult behaviour.

In its natural habitat, M. quadrata is typically found growing on thin soil covering granitic rocks, usually along stream banks, and tends to occupy relatively drier situations than both M. polymorpha and Conocephalum.

Unlike M. polymorpha, young plants of M. quadrata lack specialised cells for essential oil storage.