Bryophyte // Amphibians of plant kingdom

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1. BRYOPHYTES

2. Bryophytes are among the simplest of the terrestrial plants. Lack complex tissue system. Most of them are 2–5 cm tall or others less than 10 cm long.  Commonly grow in damp, humid and shaded localities. widely distributed throughout the world.  They are called amphibians of the plant kingdom because they can live in soil but are dependent on water for sexual reproduction. HABIT & HABITAT

3. The plant body is thallus -like and prostrate or erect. The body is attached to the substratum by rhizoids. They lack true roots, stem or leaves. They may possess root-like, leaf-like or stem-like structures. STRUCTURE Funaria

4. SEX ORGANS The main plant body of the bryophyte is haploid(n). It produces gametes, hence is called a gametophyte. The sex organs in bryophytes are multicellular .

5. Antherozoids are released into water and come in contact with archegonium . Egg (n) + Antherozoid (n) = Zygote (2n) Zygotes grows into sporophyte . The sporophyte is not free-living but attached to the photosynthetic gametophyte and derives nourishment from it. Some sporophytes undergo meiosis, a reductional cell division, to produce haploid spores. Spores germinate to produce gametophyte. FERTILISATION

6. Ecological importance in succession - pioneers in establishing vegetation in the barren rocks. Prevent soil erosion Provide food - Some mosses provide food for herbaceous mammals, birds and other animals Good Packing material – Sphagnum  used to pack bulbs, cuttings and seedlings for shipment Used in seed beds and green houses. Source of fuel - Sphagnum provide peat which is a potential source of coal and used as fuel. Absorbent bandages - Sphagnum plants are slightly antiseptic and possess superior absorptive power. Economic Importance

7. TYPES OF BRYOPHYTES

8. LIVERWORTS liverworts are small, less than 10 cm long thallus body. The thallus is dorsiventral and closely appressed to the substrate. They have rhizoids,  flattened stems with overlapping scales or leaves. They usually grow in moist, shady habitats such as banks of streams, marshy ground, damp soil, bark of trees and deep in the woods. The leafy members have tiny leaf-like appendages in two rows on the stem-like structures. e.g., Marchantia .

9. Fragmentation Gemmae Marchantia  produce special structures on their dorsal structures called gemma cups . Gemma cups give rise to very tiny, lens shaped bodies called gemmae . The gemmae become detached from the parent body and germinate to form new individuals. Asexual Reproduction

10. Male and female sex organs are produced either on the same or on different thalli . The male gametes are called antherozoids . The female gametes are called archegoniophore . Antherozoid reach to the archegonia tip with the help of water and gets fused  with egg and zygote is formed. Sexual Reproduction Male thallus , Marchansia Female thallus , Marchansia

11. The zygote undergoes cell division during development and forms sporophyte .  The sporophyte is differentiated into a foot, seta and capsule. The capsule is surrounded by a layer called jacket. After meiosis, spores are produced within the capsule.  These spores germinate to form free-living gametophytes. SPOROPHYTE

12. Life cycle of Marchantia

13. MOSSES Mosses are small nonvascular bryophyta . They grow in dense green clumps or mats, often in damp or shady locations. They have root-like multicellular rhizoid. They have haplo-diplonts : haploid (n) and diploid (2n) life forms alternate to each other. It’s predominant stage of the life cycle is gametophyte. Funaria

14. Gametophyte consists of two stages. Protonema stage develops directly from a spore. It is a creeping, green, branched and frequently filamentous stage. Leafy stage develops from the secondary protonema as a lateral bud. MOSSES

15.   Antherozoids (n) + Egg cells (n) = Zygote (2n) After fertilisation, the zygote develops into a sporophyte , consisting of a foot, seta and capsule. The sporophyte consists of three structures: i ) Foot - anchors it to the gametophyte and helps to transfer water and nutrients from the gametophyte. ii) Seta - a long erect stalk iii) Capsule - produce spores  Spores are formed after meiosis. Funaria MOSSES

16. Polytrichum Sphagnum When spores fall onto ground, it may germinate into a branching, threadlike filamentous protonema. Buds from the protonema grow into leafy male or female gametophytes Examples : Funaria , Polytrichum and Sphagnum MOSSES