vegetative and reproductive structures of Chara

vegetative and reproductive structures of Chara

1. CHARA

2. CHARA Division Chlorophyta Class Chlorophyceae Order Charales Family Characeae Genus Chara

3. Occurrence Freshwater Plants encrusted with calcium carbonate - Stone warts

4. Vegetative structure Multicellular , macrosopic filamentous, branched Main axis , rhizoids Rhizoids - lower end, branched, multicellular , uniseriate , obliquely septate , no nodes and internodes, Arise from rhizoidal plates fixation

5. Main axis Erect, branched Differentiated into nodes and internodes Internodes – long, single celled, enveloped by corticating threads Nodes – short, regularly arranged cells Bears branches - Branches of limited growth (short laterals) - Branches of unlimited growth (long laterals)

6. Branches of limited growth (short laterals) primary laterals, leaves or branchlets Arise from peripheral cell of the node Limited growth Limited number of nodes and internodes Arise shorter, unicellular branches from nodes - -- secondary laterals bear stipules Fertile branches bear sex organs

7. Branches of unlimited growth (long laterals) arise from axils of primary laterals Arise singly unlimited growth/indefinitely nodes and internodes, Cortication bears primary laterals

8. Cell structure Two types of cells At the apex- & at the nodes Small & isodiametric Central nucleus Granular cytoplasm Chloroplst - numerous, discoid, evenly distributed, no pyrenoids

9. Cell structure Internodal cells elongated large vacuole, cytoplasm & nuclei- peripheral Chloroplast- discoid, numerous, longitudinally Cytoplsm – peripheral stationary layer- exoplasm inner fluidy endoplasm Movement- cyclosis Cell wall – cellulose, hemicellulose , lignin, pectin Mucilage covering, Calcium carbonate

10. Cortication Internodal cell ensheathed by elongated corticating threads Thread consist of smaller cells Half of corticating arise from uppernode , others from lower node

11. Reproduction Vegetative & sexual methods Vegetative – amylum stars, bulbils, 2 protenema a) Amylum stars star shaped aggregate of vegetative cells Lower nodes Store reserve food Detach from parent ----- new plants

12. Vegetative reproduction b)Bulbils Small, rounded, tuber-like structures, develop on rhizoids c) Secondary protenema nodes/rhizoids Protenema like structures ----new plants

13. Sexual reproduction Oogamous Sex organs large & visible Male sex organ- antheridia/globules Female sex organ – oogonia / nucules Homothallic ( monoecious ) – both on same plant Heterothallic ( Dioecious )- different plants Nucule is always above the globule

14. Globule/ antheridium Large, spherical, Red/bright orange coloured Stalk – pedicel Outermost wall -8 large closely fitted curved cells- shield cells e ncloses an internal cavity

15. Globule/ antheridium Manubrium – center of shield cell- rod shaped handle like cell 1 o capitula - more or less rounded cells at the end Inturn posess 2 o capitula branched or unbranched antheridial filaments/ spermatogenous filaments

16. Matre Globule/ antheridium Schield cells move apart Expose antheridial filaments 200 androytes Elongated coiled biflagellated antherozoid

17. OOGONIUM ( Nucule ) Macroscopic Short stalk Node Homothallic- Nucule is always above the globule Tube cell- 5 , spirally twisted, cover, except at the tip Corona cell- 5, at the tip Egg- center, uninucleate Rich of food materials- oil drops & starch grains Receptive spot - tip of the egg, hyaline

18. Fertilization Numerous biflagellate antherozoids liberated outside Swim- -water –reach nucule Tube cells elongate near the tip- form neck Narrow central slit in the corona – passage for antherozoids Only one penetrate the wall- fuse with the egg-zygote

19. Germination Diploid nucleus migrate towards apex Secrete cellulosic cell wall Yellow/ brown Wall of the tube cell & oogonium -thick & sculpturing Zygote settles at the bottom Undergo resting period

20. Germination of Zygote