The region of the thallus that produces food in the process of photosynthesis is called the photosynthetic region. This region is made up of many filaments. Filaments are slender, threadlike, long, sessile, multicellular and green in colour. These are called assimilation formulas. Each sutra consists of one large and colorless cell at the tip. The space between two adjacent cells is called an air pocket. It contains air. Each air cell has an air hole at the top. Air moves through these holes. This region is green and produces food through the process of photosynthesis.

(i) Photosynthetic region: The region of the thallus that produces food in the process of photosynthesis is called the photosynthetic region. This region is made up of many filaments. Filaments are slender, threadlike, long, sessile, multicellular and green in colour. These are called assimilation formulas. Each sutra consists of one large and colorless cell at the tip. The space between two adjacent cells is called an air pocket. It contains air. Each air cell has an air hole at the top. Air moves through these holes. This region is green and produces food through the process of photosynthesis.
(ii) Storage Zone: The area of the thallus where food is deposited or stored is called the storage zone. It is colorless, multicellular, devoid of intercellular spaces and composed of parenchyma cells. This region does not produce food, but stores carbohydrates. Unicellular rhizoids and multicellular scales are produced from this region.
(iii) Genus: Riccia is a companion plant. Its male and female genitalia are located in the same thallus. Male genitalia are called antheridium and female genitalia are called archegonium.
* Antheridium: On the surface of the thallus, several stamens antheridia grow. It is round and pear shaped. Inside the antheridium are the sperm mother cells. Two biflagellate spermatozoa are produced from each sperm mother cell.
* Archegonium: Within the thallus several cup-shaped or flax-shaped female archegonia grow. It consists of two parts. Neck and Abdomen. The neck is slightly curved and consists of few neck duct cells. Abdomen contains an ovary and an abdominal duct cell.
(iv) Hypodermis: The hypodermis is composed of single cells below the accumulation zone of the thallus. Unicellular smooth or rough rhizoids and multicellular scales are formed from the epidermis.

Thin, filiform, unbranched, colorless and multicellular scales arise from the lower part of Riccia thallus. It attaches the thallus to the soil or other material and absorbs water and mineral salts. Scales protect the thallus from desiccation in unfavorable environments. Aquatic species of Riccia lack scales.

Slender, filamentous, unbranched, colorless unicellular rhizoids arise from the lower part of Riccia-thallus. It is of two types. Smooth and rough rhizoids. The irregular rhizoids have nail-like nodules. Rhizoids anchor the thallus to soil or other material and absorb water and mineral salts. Aquatic species of Riccia do not have rhizoids.

Riccia is a gametophyte plant. Its body cannot be divided into roots, stems and leaves. That is, they are thallus shaped. Thallus green, obtuse, succulent, recumbent, opposite and flattened. It is bifurcated. Each branch has a large groove at the tip. It is called apical notch. The surface of the thallus has a longitudinal groove. This is called dorsal groove. A median vein runs longitudinally along the dorsal groove. Many thallus arranged together like rose petals. This condition is called rosette. The thallus bears gemma cups which reproduce by organogenesis. Being green, it can produce food through the process of photosynthesis.

(i) Thallus: Riccia is a gametophyte plant. Its body cannot be divided into roots, stems and leaves. That is, they are thallus shaped. Thallus green, obtuse, succulent, recumbent, opposite and flattened. It is bifurcated. Each branch has a large groove at the tip. It is called apical notch. The surface of the thallus has a longitudinal groove. This is called dorsal groove. A median vein runs longitudinally along the dorsal groove. Many thallus arranged together like rose petals. This condition is called rosette. The thallus bears gemma cups which reproduce by organogenesis. Being green, it can produce food through the process of photosynthesis.
(ii) Rhizoids: Slender, filamentous, unbranched, colorless unicellular rhizoids arise from the lower part of Riccia-thallus. It is of two types. Smooth and rough rhizoids. The irregular rhizoids have nail-like nodules. Rhizoids anchor the thallus to soil or other material and absorb water and mineral salts. Aquatic species of Riccia do not have rhizoids.
(iii) Scales: Thin, filiform, unbranched, colorless and multicellular scales arise from the lower part of Riccia thallus. It attaches the thallus to the soil or other material and absorbs water and mineral salts. Scales protect the thallus from desiccation in unfavorable environments. Aquatic species of Riccia lack scales.

Riccia is a plant of Hepatic family. Members of the class Hepaticae are known as Liverwort. Liver means human liver. The shape of the Riccia thallus is somewhat similar to the human liver. That is, Riccia looks a lot like a liver or a leaf or a pepper. Hence Riccia is called Liverwort. For example – Riccia dhakensis.

1. It is a gametophytic (haploid) plant.
2. Its body is thalloid i.e. the body cannot be divided into roots, stems and leaves.
3. Its thallus is green, recumbent, hemispherical and flattened. Dr. Siddique Publications
4. The thallus is bifurcated and each branch has a groove at the head.
5. The lower surface of the thallus consists of unicellular smooth and irregular rhizoids and multicellular scales.
6. The upper part of the thallus is green and capable of photosynthesis and the lower part is colorless and storage zone.
7. The accumulation zone is colorless, composed of parenchyma cells and without air chambers.
8. The photosynthetic zone consists of air chambers and the chambers are directly exposed to the air. Dr. Siddique Publications
9. They are homosporous. ie produce identical spores.
10. Spores are released as a result of decay of the thallus.
11. The female genitalia is an archegonium and is fluted or pitcher-shaped in appearance.
12. The stamens are the antheridium and appear pear-shaped, round, oval or cylindrical.
13. The sporophyte is dependent on the gametophyte.
14. They reproduce asexually and sexually.

Kingdom : Plantae
Division : Bryophyta
Class: Hepaticae
Order: Marchantiales
Family : Ricciaceae
Genus : Riccia

Riccia is found in almost all countries of the world. They are born in clusters in round clusters during monsoons. They grow on moist or damp soil and moist walls. The only species Riccia fluitans grows floating in water. Various species of Riccia grow in mountainous regions including Sylhet, Bangladesh.