Plant Biology and Classification

Marchantiales are characterized by the presence of scales on the thallus. Leafy Jungermanniales have archegonial necks composed of five vertical rows of cells. In Anthocerotales, the archesporium arises from the amphithecium, and in Funariales, elaters are absent in the capsule.

In Marchantia, the entire endothecium of the developing sporophyte differentiates into the archesporium (sporogenous tissue), which later gives rise to spore mother cells and elaters. In contrast, in Anthoceros and Sphagnum, the archesporium is derived from the amphithecium.

Mosses are small flowerless plants that grow in shady regions having adequate moisture. These are spore producing plants. Common examples of mosses include Sphagnum, Funaria and Polytrichum. Sphagnum is commonly called as peat moss. Funaira is a water moss that grows in shady, damp places. Polytrichum is commonly called as haircap moss. Riccia is a genus of liverworts

Both Riccia and Marchantia belong to Class Hepaticosida/Hepaticae that includes 3 orders, the two genera belong to Order Marchantiales, that has specialized vertical stalks called the archegoniophores and serile cells called elaters in the sporangium. The plant body shows dichotomous branching.

Riccia is a liverwort (Hepaticae), which grows predominantly in wet terrestrial habitats and are free-floating or submerged aquatic.

The only aquatic bryophyte is Riccia fluitans, or crystalwort, which  is a floating bladderwort. Sphagnum is also called as peat moss or bog moss. The sporophyte is completely surrounded by a tough protective covering called the calyptra. The new adult gametophytes grow from a tiny bud that develops on the protonema.

Mosses and liverworts occur in a variety of habitats. These non-vascular plants (bryophytes) lack well developed water conducting tissue and tend to be most abundant in moist areas, such as the splash zones of a waterfalls, or in the higher elevation forests that are frequently enveloped in fog.
Mosses and liverworts contain photosynthetic pigments and, like more advanced plants, produce their own food from sunlight. Mosses typically have small leaves arranged in a whorl around a short stem. Liverworts are closely related to mosses, but can usually be recognized by their larger flattened leaves that grow in two rows.

A unique feature of hornwort is that the sporophytes, unlike that of mosses and liverworts, continue to grow from their bases for the remainder of the gametophyte's life, a characterstic known as indeterminate growth. Hornwort sporophytes are characterised by a basal (or intercalary) meristem that continuously develops new sporangial tissue (indeterminate growth). However, the sporangium does not grow indefinitely.

In Riccia, the sporogonium which is the sporophyte individual differs from the thallus (gametophytic plant) in structure, function and genetic constitution as well. The thallus is green in colour and autotrophic. The sporogonium has no colour and is heterotrophic in its nutrition. The thallus represents the haplophase where as the sporogonium represents the diplophase. Unlike other liverworts, the embryo, sporogonium and spore mother cells in Riccia do not develop chloroplasts. The sporophyte remains totally dependent on the thallus for food materials, water and minerals in solution.

The sporophyte of Riccia is the simplest because as it contains only capsule, both the foot and seta are absent. It consists a peripheral layer of cells constituting the capsule wall and a central mass of spore mother cell which produces spores.

Sphagnum is the scientific name of peat moss. It is also called as bog moss. It has high pH. Hence, it is used for plants growing in acidic condition, such as blueberries. It helps in moisture absorption from soil.

Sphaerocarpos is a genus of liverwort. Division bryophyta is divided into three classes namely, Hepaticopsida (liverwort), Anthoceropsida and Bryopsida. Liverwort is divided into four orders namely, Marchantiales (example: Riccia), Sphaerocarpales (example: Sphaerocarpos), Jungermanniales (example: Pellia) and Calobryales (example: Calobryum).

Archegoniophore is a stalk of a prothallium on which archegonia grows. Marchantia is a genus of liverworts. The thallus of Marchantia is dioecious in nature. It produces either female archegoniophores or male antheridiophores. 

The upper part of the thallus shows well-developed air chambers bounded on all sides by plates of cells, below by the storage tissue and roofed in by an epidermal layer of cells; each chamber is open to the air by a simple pore.