Plant Biology and Classification

In the life cycle of Funaria, two distinct individuals occur. One of these is haploid and is the independent leafy plant. The other is diploid, leafless sporogonium. It is partially dependent on the leafy gametophyte for its nutrition.

Sex organs in Funaria develop at the tip of gametophore since the plant itself constitutes the gametophytic phase. After fertilization develops the capsule from which protonema develops from the spores that dehisces from the capsule. The capsule constitutes the sporophytic phase. The plant shows an alternation of generation, between the sporophytic and gametophytic phase.

The mature sporophyte of Funaria is much more complex than that of the liverworts. It is differentiated into foot, seta and capsule. The foot forms the basal portion of sporophyte. The seta is a long cylinder reddish brown, stalk-like structure. It carries the capsule at its top and raises it more than an inch above the apex of the leafy gametophore.

In Funaria, fertilization occurs, as in other Bryophytes, when the plants are wet with rain or dew. The apical cell of the antheridium, which forms operculum absorbs water and bursts. The spirally coiled bi-flagellate antherozoids escape from antheridium, while still enclosed within a vesicle. The vesicle eventually dissolves in water and the antherozoids are set free. They reach the archegonial cluster.

The diploid sporophyte or sporogonium reproduces by spores and represents the asexual generation. The mature sporophyte of Funaria is differentiated into foot, seta and capsule. 

Antheridia are borne in groups at the expanded convex apex of the antherdiophore. The archegonial branches arise laterally at the base of the male branch. Achegonia are borne in groups at the apex of these branches.

The life cycle of Funaria is haplo-diplontic type. In the life cycle free living haploid gametophyte alternates with a semiparastitic diploid sporogonium (Sporophyte). In this type alternation of generations is called as heteromorphic or heterologous. In Funaria the main plant body is free-living gametophyte (n) which exist in 2 forms i.e. protonema (juvenile gametophyte) and leafy gametophore (adult gametophyte). The leafy gametophyte is the dominant phase of Funaria as the vegetative body of itself is represented by these leafy gametophores. It has two distinct growth stages, a prostrate filamentous alga-like protonema and an upright gametophore.

Apophysis is the solid, somewhat swollen basal, green photosynthetic portion of the capsule. It is sterile in nature. It also helps in conduction of water and food materials. It gradually narrows down into seta; hence it is also called as the neck of the capsule. Internally the apophysis is covered by epidermis. In capsule of Funaria stomata present only in apophysis.

A mature archegonium has a long columnar stalk, a swollen venter and an elongated neck. The wall of the venter is two layered, but that of neck is single layered consisting of cells arranged in six rows. The neck encloses an axial row of six or more neck canal cells. Neck consists of 6 or more neck canal cells (6-11).

In Funaria, stomata are absent in leaf and is present in capsule (apophysis). Internally the apophysis is covered by epidermis. The epidermis is interrupted by stomata, which leads into air space below, called as the sub stomatal cavity. Within the epidermis is a broad spongy zone of sterile cells, rich in chloroplasts. There are distinct intercellular spaces between these cells. Stomata in present only in the apophysis, which is present at the basal part of the capsule.

The spores of Funaria are 12 - 20 microns in diameter, and represent the first cell of the gametophytic generation. The spore wall consists of two layers, the outer smooth and brown coloured exosporium, and the inner colourless endosporium. The cytoplasm of spore is rich in oil globules and chloroplasts. The spore germinates under favourble conditions. The exospore is ruptured and the endospore produces a papilla. It soon forms a long filamentous protonema. The protonema shows apical growth and forms two types of branches, the chloronemal branches and the rhizoidal branches.

The sporophyte of Funaria starts developing within the archaegonia. The sex organs, antheridia and archegonia develop at the apices of seprate erect branches, called as gametophores. In the archaegonium the sporophyte is formed. A mature archegonium is flask shaped, which is borne on short stalk. It has a basal swollen part of venter and elongated neck. The venter is surrounded by a two layered jacket, whereas the jacket around the neck is singled layered. 

Elaters are present in hepaticopsida (marchantia). Pseudoelators are present in Anthocerotopsida, and elaters are absent in Bryopsida. As funaria belongs to Bryopsida, do not have elaters.

In Funaria, the antheridial head contains sterile, club-shaped hairs known as paraphyses. These help in protection and water retention for the antheridia.

In bryophytes, the sporophyte is physically attached to and nutritionally dependent on the gametophyte throughout its life.