Bryophytes- Introduction and types for every - neet aspirants

 Introduction

Bryophytes is a multicellular, primitive and seed less plant.  Bryophytes is also non-flower plant. Bryophytes is also called amphibians of plant because habitat is terrestrial but they required water for fertilisation . They have thyroid structure but more differentiate from algae. The bryophytes consists Approx 20,000 species of the plants .

Habitat- They found in moist shady place. Such as hilly areas and river banks.

Structure-they have thalloid structure(prostrate and erect thallus) but more differentiate from algae. They have root like, stem like ,leaf like structure while true roots and true stems are absent.and have rhizoide (thread like structure) for water absorption.

Reproduction:

Asexual reproduction: by fragmentation, through the Gammae cup in liverworts and budding in protonema.

Sexual reproduction:  sexual reproduction by the fusion of two gametes. They have a female sex organ (archegonium) which large and non- motile and a male sex organ (anthridium) which is small and motile ( have two flegella ) Anthridium move towards the archegonium through the water and fused with archegonium and form zygote. So fertilisation is internal.

If archegonium and Anthridium present on same thallus, this type of thallus called bisexual thallus.

And If archegonium and Anthridium present on the different thallus, this type of thallus called unisexual thallus.

Life cycle: bryophytes have haplodiplontic life cycle because haploid as well as diploid phase both are dominant.but main plant body is gametophyte because diploid phase depend on haploid phase.

Types of bryophytes:

1)Hepatocopsida( liverworts):

Habitat- They only grow in moist, shady areas such as marshy ground, damp soil, bark of trees. Approx 10,000 species present in the world.

Structure of liverworts (marchentia):

Thallus grow horizontally and closely appressed to substratum and leaf like horizontal thallus. They have unicellular rhizoids for absorption of water. 

Life cycle: 

Male (n) and female(n) gamete fused and forms zygote (2n). Which is sporophyte and they not release direct spores they show mitosis and form big sporophyte (2n) upper part is capsule middle party Seta and lower part is foot. Spores form in capsule by miosis and when this spores come out forms the capsule,form gametophyte.

Reproduction of liverworts:

Asexual reproduction by fragmentation and gammae cup on the upper surface of thallus. and Gammae bud is a multicellular, photosynthetic and green part present in Gammae cup. They  form New thallus and Gammae bud is haploid(n) because they form on on the surface of gametophyte.

Eg: marchentia

2)Bryopsida(mosses):

Habitat: They found in damp and shady areas such as bank of river and hilly areas. Moss number is  approx 5,000 in the world.

Structure: 

Main plant body is gametophyte and thallus is erected. Multicellular Rhizoid present on the base of stem. spiraly arrangement of leaf on the stem.

Life cycle:

In protonema Male (n) and female(n) gamete fused and forms zygote (2n). Which is sporophyte and they not release direct spores they show mitosis and form big sporophyte (2n) upper part is capsule middle party Seta and lower part is foot. Spores form in capsule by miosis and when this spores come out forms the capsule they form primary  protonema and further form secondary protonema and bud form on the secondary protonema, these buds form New gametophytes.

Reproduction: asexual reproduction by fragmentation and budding in protonema.and maily bisexual  thallus in sexual reproduction.

Eg: funaria and polytrichum.

3)Anthocerapsida(hornworts):

Habitat: they are found in damp and shady areas such as hilly places.

Structure: they have lobbed form and irregular outlining  gametophyte. And the sex organ submerge in gametophyte.

these are the first member which sporophyte does not depend upon gametophyte due to presence of cuticle which prevent the loss of water and  they can prepare own food through photosynthesis.and meristematic tissue present in between foot and spores region.

Life cycle: 

male and female gamete fused and form zygote which developed into the sporophyte,debt relief sports and these spores  form gametophyte. And they develop long and slender sporophyte.

Reproduction:

Sexual reproduction: male sex organ (antheridium) move towards the female sex organ (archegonium) through the water and fuse, fertilized egg which present in female sex organ developed into elongate sporangium. And these are splits according to length and grow, when they grow than release spores.