Introduction: Liverworts are a type of non-vascular plant which belongs to the division Marchantiophyta. The thallus of liverworts is a flat structure that resembles a leaf.

Dorsiventral Thallus: The thallus of liverworts is dorsiventral, which means it has two distinct surfaces - a dorsal surface and a ventral surface. The dorsal surface is the upper surface that faces towards the sun, while the ventral surface is the lower surface that faces towards the substrate. The dorsal surface is usually dark green, and it is covered with pores called stomata, which allow the exchange of gases between the plant and the atmosphere. The ventral surface is usually lighter in color, and it is closely appressed to the substrate.

Adaptations of Dorsiventral Thallus: The dorsiventral thallus of liverworts has several adaptations that help the plant survive in its environment. These adaptations include:

- Increased surface area for photosynthesis: The dorsal surface of the thallus has a large surface area that is exposed to sunlight, which allows the plant to carry out photosynthesis.

- Protection from desiccation: The ventral surface of the thallus is closely appressed to the substrate, which helps to reduce water loss through transpiration.

- Absorption of nutrients: The ventral surface of the thallus is in close contact with the substrate, which allows the plant to absorb nutrients and water from the soil.

- Anchorage: The ventral surface of the thallus is also used for anchorage, which helps to keep the plant in place.

Conclusion: In summary, the thallus of liverworts is dorsiventral, which means it has two distinct surfaces - a dorsal surface and a ventral surface. The ventral surface is closely appressed to the substrate and has several adaptations that help the plant survive in its environment.

The thallus of liverworts is may not mention in book as in diagram u may check it on google..bt its thallus is dorsiventrally attached to the unicellular rhizoids as a holding substrate ....which u means they r appressed ..simply they r attached in dorsiventrally to their rhizoids as form their substrate.hope this helps u little.