In the capsule of many mosses, such as Funaria, the spore sac is connected to the capsule wall by a network of filaments known as trabeculae. These structures provide structural support and facilitate the transport of nutrients to the developing spores within the spore sac.

The ventral surface of the Riccia thallus is characterized by the presence of rhizoids and scales. Rhizoids are unicellular, hair-like structures that serve the primary function of anchoring the plant to the substrate and absorbing water and minerals from the soil.

Most species of the genus Riccia are monoecious, meaning that both male (antheridia) and female (archegonia) reproductive organs are produced on the same thallus. This condition facilitates self-fertilization, which is a common reproductive strategy in many liverworts to ensure reproductive success in varying environmental conditions.

Under unfavorable environmental conditions, such as drought, some species of Riccia develop specialized vegetative structures known as tubers. These tubers are thickened, starch-storing portions of the thallus that remain dormant in the soil and regenerate into a new thallus when favorable conditions return.

The genus Riccia is classified under the class Hepaticae, commonly known as liverworts. While it belongs to the division Bryophyta, Hepaticae is the specific class. Marchantiales is the order, and Ricciaceae is the family, making Hepaticae the correct taxonomic class designation within the provided options.

The apical notch of the Riccia thallus contains a group of meristematic cells. Observations of the growth region indicate that the apical growth is maintained by a small group of initial cells, typically arranged in a row of 3 to 5 cells that facilitate the dichotomous branching of the thallus.

The spore wall in Riccia, like many bryophytes, is differentiated into distinct layers. The outer layer is the exosporium, the middle layer is the mesosporium, and the innermost layer is the endosporium. These layers provide protection to the developing spore.

In many bryophytes, the developing spores within the sporangium are nourished by specialized layers of cells, often referred to as the tapetum. Depending on the specific genus, this nutritive tissue may consist of one or two layers, both of which serve to support the maturation of the spores.

The venter is the basal, swollen portion of the archegonium that contains the egg cell. In Riccia, the wall of the venter is typically composed of a single layer of cells. Observations of cross-sections of the venter wall in various Riccia species generally show a range of 12 to 20 cells forming the perimeter.

The archegonium is a flask-shaped female reproductive organ. It consists of a long neck and a swollen base known as the venter. The venter houses the egg cell, which is the site of fertilization, and is protected by a layer of sterile cells.