Liverworts

Liverworts are one of the two groups of bryophytes. They favour moist, shady habitats and are typically found along the banks of streams, on marshy ground, on damp soil, on the bark of trees, and deep within woodlands.

The plant body

In most liverworts the body is thalloid, meaning it is a flat, simple sheet of tissue rather than one built from stem and leaves. A well-known example is Marchantia. The thallus is dorsiventral, having a distinct upper and lower surface, and it lies closely pressed against the surface on which it grows. Some liverworts are leafy rather than thalloid; in these the stem-like structure carries tiny leaf-like appendages arranged in two rows.

Asexual reproduction

Liverworts can multiply without sex in two ways.

• By fragmentation, in which the thallus breaks into pieces and each piece can grow into a new plant.
• By producing special structures called gemmae (a single one is a gemma). Gemmae are green, multicellular asexual buds. They form inside small cup-shaped receptacles called gemma cups that sit on the surface of the thallus. When a gemma separates from the parent, it germinates to grow into a new, independent individual.

Sexual reproduction …