Bryophytes

 

Funaria

 

Distribution of Funaria

Funaria is the most prominent genus in the family Funariaceae. It is represented by about 117 species and is found in all parts of the world.

The species of Funaria are terrestrial mosses and grow as green velvety patches in shady and damp places such as moist walls, burnt soil, and the trunks of trees, during the rainy season.

Funaria hygrometrica is the most common species and is called cord  moss due to its twisted seta.

·         Some of the common Funaria species are F. hygrometrica, F. flavicans, F. apophysata, F. arctica, etc.

 

External Morphology

Funaria is divided into two stages: leafy gametophyte and sporophyte.

The gametophyte is the main plant body that is represented by a juvenile and an adult stage.

The haploid plant body is divided into stem, leaves and rhizoids.

The stem is erect, branched, green and photosynthetic. The branches arise from the lower portion of the stem.

The leaves are arranged spirally on the stem. They are scattered towards the base and crowded at the apex. They are sessile and almost ovate in shape and have a distinct midrib.

The stem is fixated on the substratum by rhizoids. They are branched, multicellular and appear like root hairs.

The gametophytic plants are monoecious and homothallic. The male reproductive organ or antheridium and the female reproductive organs or the archegonium are borne on different branches of the same plant.

Both the antheridium and archegonium are produced in clusters at the end of antheridial and archegonial branches, respectively.

The sporophyte is attached to the archegonium in parasitic nature and is divided into a foot, seta and capsule.

 

Internal Morphology of Funaria

Internal morphology, or the internal structure of the  plant body, is the anatomy of Funaria.

Axis or Stem Anatomy

In a transverse section, the mature stem of Funaria shows three distinct regions: the epidermis, the cortex, and the central conducting strand or central cylinder.

Figure: T.S. of stem showing different parts

Epidermis

The epidermis is the outermost layer of the stem. It is generally one cell thick and consists of small thick-walled tangentially elongated chlorophyll-bearing cells.

Cuticles and stomata or pores are absent in the epidermis.

Cortex

The cortex lies in between the epidermis and the central cylinder. It is many-layer in thickness and composed of large parenchymatous cells.

In the younger part of the stem, the cells of the cortex contain chloroplasts. However, they are lacking in the older section.

As the stem matures, the outer cells of the cortex become thick-walled and are reddish-brown in colour. While the inner cells of the cortex are thin-walled.

The cortex also contains isolated leaf traces (patches of small cells) in the peripheral region.

Central Conducting Strand or Central Cylinder

The central conducting strand or central cylinder is made up of long, narrow, thin-walled colourless cells. These cells lack protoplasm and are called hydroids (dead cells).

The hydroids possibly help in the upward conduction of water and mineral nutrients.

Leaf Anatomy

In a transverse section, the leaf of Funaria shows a well-developed midrib with two lateral lamina, or wings.

Figure: T.S. of leaf

The midrib is several cells thick. It has a small central strand of slightly narrow, thick-walled cells called stereids. They help in conduction.

The leaf lamina is made up of a single layer of parenchymatous polygonal cells. These cells are elongated, thin-walled, and contain large and prominent chloroplasts.

Reproduction in Funaria

Funaria reproduces by vegetative and sexual methods.

Vegetative Reproduction

Vegetative reproduction in Funaria occurs by the following methods:

Fragmentation of Primary Protonema

In Funaria, the spore on germination develops a branched, filamentous structure called the primary protonema.

Under certain circumstances, the primary protonema forms specific colourless separation cells by intercalary divisions. As these cells die, they break up the protonema into several fragments.

The fragments develop into new protonema. Each new protonema bears buds that grow into leafy gametophores.

Secondary Protonema

The protonema that develops from any part of the  plant other than the germination of the spore is known as secondary protonema. It may develop from any injured part of the gametophyte, such as rhizoids, stems, leaves, or reproductive structures.

Each secondary protonema forms buds and grows into gametophores