2. GUIDED BY: M.NIRMALA. DONE BY:U.SABARISH. N.T.KISHORE KUMAR. B.SATISH KUMAR. V.PAVAN KUMAR. T.JAYA KUMAR.

3. BRYOPHYTA The Bryophyta can be considered to be the precursors of the terrestrial plants.In this chapter you are going to study the example- polytrichum.

4. EXTERNAL STRUCTURE (MORPHOLOGY) The structure of the plant body is divided into an with small leaves.The young leaves are spirally arranged in three rows at the tip of the stem.

5. REPRODUCTION. Polytrichum undergoes vegetative and sexual reproduction.vegetative reproduction takes place by various ways by primary protonema as well as by the formation of gemmae.

6. The male gamete is chemotacally attracted by the mucilaginous sap at the mouth of the archegonium. The fertilized egg forms the diploid zygote. FERTILIZATION FERTILIZATION

7. CONCEPTS. After fertlisation the diploid zygote produces the sporophyte. Polytrichum is dioecious. The male sex organ is called the antheridium and the female sex organ is called the archegonium.

8. SPOROPHYTE AND CAPSULE The upper part elongates into a slender ‘seta’ that bears the capsule at the tip. The central region of the capsule is formed of elongated cells called columella.

9. Dispersal of the spore The peristome has 32 to 64 teeth. There is a ring of pores in between these teeth –like structures. The spores are liberated out through these pores by the action of the wind.

10. On falling onto a suitable substratum the Spores germinate into a new plant. Usually In the life cycle of polytrichum, the sporophyte is totally dependent on the gametophyte.