Tag: plant kingdom

In Funaria, the spore mother cells are the last structures of the sporophyte generation. They differentiate by meiosis into spores, which are haploid. The spores are, therefore, the first structures of the next gametophyte generation.

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. 

In Funaria, the androcyte mother cells divide diagonally and each forms two androcytes. The latter differentiate into biflagellate antherozoids. 

Rhizoids are branched, slender and multicellular. They are stout, brown, almost cable like and form the main anchoring strands. The rhizoids are colourless in the young stage, but become red or brown at maturity. The rhizoidal branches have oblique cross walls and grow down into soil. They help in anchorage and absorption.

The peristome lies immediately below the operculum. It consists of two sets of long, conical teeth, one within the other. There are sixteen teeth in each set. The teeth of both the sets are on the same radii and thus opposite to each other.

When the mature capsule begins to dry up the thin walled cells of the annulus break and the operculum is thrown away. Dropping off the operculum is assisted by the outward hygroscopic movement of the underlying peristomial teeth. Due to this movement, slits between the inner thin walled peristomial teeth become wider and spores escape gradually through these slits. In a wet atmosphere, the wet peristomial teeth bend inwards and thus closing the slits and prevent the escape of spores. The seta of the mature sporophyte also exhibits hygroscopic movements. In dry weather, by loosing water, it twists and bents, thus helping in dispersal of spores.

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.

Spore is the first cell of gametophytic generation. On a suitable damp habitat, a meiospore of Funaria germinates into a filamentous green alga-like structure called protonema. Protonema has green epiterranean chloronemal branches (chlornema) and non-green subterranean rhizoidal branches (caulonema). The protonema of moss, represents the juvenile stage of gametophyte. 

A female gametangium of bryophyte differ from fungus multicellular sex organs surround by a single layered jacket of sterile cells.

The haploid phase in the life cycle of Funaria is represented by independent leafy gametophyte. The gametophyte is developed from the spore.