Tag: biology

In moss, 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. The sporogonium of Funaria is photosynthetic, hence semi-parasitic on gametophore. It differentiates into foot, seta and capsule. The foot embedded in the female receptacle and absorbs inorganic nutrients.

Vegetative propagation in Funaria takes place by various methods like- fragmentation of the primary protonema, secondary protonema, gemmae, bulbils, apospory.

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.

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.