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Selaginella zk
- 1. Topic SELAGINELLA PRESENTATION PRESENTED BY GROUP 2 JAWAD UL ISLAM JUNAID UL ISLAM ZAIN UL ABIDIN AREEB NAWAZ PRESENTER ZAHEER KHAN ATTIYA REHMAN
- 2. Selaginella ( club moss or spike moss)
- 3. Table of Content • INTRODUCTION • Locality • OCCURRENCE • Classification • FEATURES • Morphology • Anatomy • Reproduction and Life Cycle
- 4. • Selaginella is a pteridophyte.It is also called spikemoss or club moss. It is the largest and the only living genus of the family Selaginellaceae.It contains more than 800 species distributed all around the world with the highest diversity found in the tropical regions. • They are seedless vascular plants. They are mostly found in shady areas, some species are also present in seasonal dry or xerophytic conditions. They are found on tree trunks, rocks, forest floors, etc.
- 5. Locality
- 6. OCCURRENCE
- 11. Root • Primary roots are short lived and the adult plant has adventitious roots • The root may arise at the point of dichotomous branching or knot like swelling present at the basal portion of the stem • Roots are endogenous in origin.
- 12. LEAVES • Epidermis is single layered. Stomata are mostly present in the lower epidermis. • Epidermis cells have chloroplasts. • Mesophyll constitutes the part between the upper and lower epidermis. It is made up of parenchyma. The number of chloroplasts in the mesophyll varies from species to species. • In some species, the mesophyll cells may differentiate into upper palisade and lower spongy tissues.
- 13. • A single median vascular bundle is present. It contains xylem tracheids surrounded by sieve elements of phloem. Phloem is surrounded by a single layered bundle sheath.
- 14. RIHZOPHORE
- 19. FRAGMENTATION • Under humid conditions in S. rupestris, branches of the stem develop adventitious branches. • These branches later disjoin from the parent plant and develop into separate individual plants.
- 20. TUBERS FORMATION • These appear at the end of the growing season. • The tubers may be aerial or subterranean. • Under favorable conditions tubers germinate into a new plant
- 21. RESTING BUDS • These are the compact structures appears at some aerial branches. • These resting buds are capable to pass on the unfavorable conditions. • Under favorable conditions these buds give off rhizophore that bear roots at their tips
- 22. SEXUAL REPRODUCTION • Selaginella is heterosporous. • It produces two kinds of spores. • The smaller microspores give rise to male gametophytes. • The larger megaspores give rise to female gametophytes.
- 23. MEGASPORANGIUM • Megasporangium is an lobed like structure • Megasporangium is bigger than microsporangium • Its colour is whitish yellow to red • Innermost layer is tapetum • Inside the wall of sporangium mass of • cell is present which further develop into megaspores
- 24. • Furthermore, through mitotic division numerous haploid tetrad megaspores are produced. • All these megaspores mother cell except one degenerate • Later through mitotic division these one spore produces only 4 megaspores in megasporangium
- 27. STRUCTURE OF ARCHGONIUM • Each archegonium is flask shape • It embedded in female gametophyte • Each archegonium consists of short neck of 2 tiers of 4 cells. • Neck enclose a single canal cell and venter consist of ventral canal cell and egg. • At maturity neck canal cell and venter canal cell disorganize and absorb water which create pressure to separate cover cell at top
- 30. Life Cycle of selaginella