life cycle of funaria

8/16/2019 life cycle of funaria

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Structure of antheridial branch and antheridia: Antheridial branch or male flower is produced at the tip

of the main stem of the gametophyte. It is surrounded by cluster of leaves called perigonial leaves.

• Antheridia are arranged in clusters, intermixed with sterile multicellular hairs called paraphyses.Paraphyses are protective in function.

• Mature antheridia are club shaped with a long, multicellular stalk and a globular body.

• The body is covered with a single layered jacket which surrounds numerous androgonial cells.

• The androgonial cells develop into antherozoids or sperms.

• Each sperm is spirally coiled, elongated structure with a pair of flagella. Mature sperms are releasedfrom the antheridium by the separation of the jacket cells.

Structure of archegonial branch and archegonia: The archegonial branches develop from the base ofthe male branches. They are covered with large leaves called perichaetial leaves. Cluster of archegonia

are found at the tip of the each

branch.

• The mature archegonium is flaskshaped with a basal multicellular

stalk, long twisted neck and a

swollen venter.

• The neck is covered with 6vertical rows of neck cells and

cover cells. It encloses more than10 neck canal cells.

• The venter is covered by 2-3layers of cells. It encloses a

venter canal cell and a basal egg

cell.Intermixed with the

archegonia, long hair-like,

multicellular paraphyses are present.

Structure of Sporophyte: The sporophyte is seen at the apex of the archegonial or female branch. Amature sporophyte shows three distinct parts – the foot, seta and capsule.

• The foot is a small conical structure embedded in the female tissue. It helps in attaching thesporophyte to the gametophyte and absorption of nutrients from it.


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• Seta is a long, slender and twisted structure. It carries the capsule at its tip.

• The capsule is the fertile structure of the sporophyte. In an L.S., it shows three distinct regions – theapophysis, theca and operculum or lid.

• Apophysis is the basal green, photosynthetic part of capsule. It has a central strand of conductingtissue.

• The theca is the urn shaped fertile, middle part of the capsule. It has a central strand of tissue called

columella which is cone shaped.

• Surrounding the columella is the spore sac. It is covered by outer spore sac wall which is 3-4 layersin thickness. The inner wall is just one cell thick. Spore sac consists of diploid archesporial cells

which after meiosis develops into haploid spores.

• Outer to the spore sac is an air space consisting of many air cavities. These cavities are traversed by

cells called trabeculae.

• Outside the air space is the capsule wall which is many layers thick. The outer layer is the epidermis.Inner to the epidermis is the two layered hypodermis of colourless cells. Within the hypodermis is the

spongy layers of green cells.

• Operculum is the terminal lid-like portion of the capsule. It is 4-5 layers thick. Inner to the

operculum is a structure called peristome. It consists of two sets of curved teeth like structures, lying

one above the other. Each set has 16 teeth. The outer peristomal teeth are hygroscopic and help in

the dehiscence of the capsule and dispersal of spores.

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When capsule is mature, it dries up, the operculum is blown up. Spores are discharged by thehygroscopic movement of peristome teeth.

Germination of the spores: During favorable conditions, spores

germinate to form a multicellular, filamentous, branched structure called

protonema. It consists of green prostrate branches called chloronemal

branches and colourless branches called rhizoidal branches. Green Bud

like structures develop on the chloronemal branches which then grow and

develop into the leafy gametophores.

©Dr. Jayakara Bhandary M. SGL in Botany, GAS College, Karwar-581301

life cycle of funaria

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