Sporocarp of Marsilea. Dr.Sukanya Baruah Chaliha. Asst. Professor Dept of Botany Class-3 rd Sem(Major) MDKG College,Dibrugarh.

Transcription

1 Sporocarp of Marsilea Dr.Sukanya Baruah Chaliha. Asst. Professor Dept of Botany Class-3 rd Sem(Major) MDKG College,Dibrugarh.

2 External Morphology Soft and green when young but turns dark brown and hard at maturity. Develops at the short branch of petiole called pedicel or stalk. The place of attachment of the pedicel with the body of the sporocarp is known as raphe. Presence of one or two teeth-like projections known as horns or tubercle at the distal end of the raphe.

3 Anatomy Wall is differentiate into three layers- The outer epidermis is made up of single layered cuboidal cell with sunken stomata. Middle layer is made up of radially elongated compactly arranged thick walled palisade cells. The third layer is comprised of more elongated thin walled palisade cells.

4 A single strong vascular strand enters near the lower horn. It is continues all along the dorsal or upper side,forming a midrib. From the midrib, lateral side branches pass on to the two sides forming a bivalved structure of the sporocarp. At the point of forking of lateral bundle, placental bundle develops.

5 Placental bundle enters into the receptacle bearing sporangia and dichotomises. A vertical longitudinal section reveals- Many sori arranged in vertical rows. Each sorus is surrounded by an indusium. Gelatinous mucilage ring is more prominant in the dorsal side.

6 A horizontal longitudinal section shows each sorus transversely- Each sorus is an elongated structure. Covered by an delicate indusium. Basipetal in arrangement,largest sporangia in top and two rows of smaller sporangia on two sides. Mucilage ring is present in the dorsal and ventral side.

7 A vertical transverse section shows- Sori on two sides. Sporophore is seen in the form of two masses on either side. The mucilage ring is present only on dorsal side.

8

9

10

11

12 CHARA Dr Sukanya Baruah Chaliha Assistant Professor Department of Botany Class-1 st sem(major) MDK College Dibrugarh, Assam

13 CHARA Division Class Order Family Genus Chlorophyta Chlorophyceae Charales Characeae Chara

14 Occurrence Freshwater Plants encrusted with calcium carbonate - Stone warts

15 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

16 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)

17 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

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

19 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

20 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

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

22 Reproduction Vegetative & sexual methods Vegetative amylum stars, bulbils, 2 0 protenema a)amylum stars star shaped aggregate of vegetative cells Lower nodes Store reserve food Detach from parent new plants

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

24 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

25 Globule/antheridium Secondary capitulum Primary capitulum Large, spherical, Red/bright orange coloured Stalk pedicel Outermost wall -8 large closely fitted curved cells-shield cells encloses an internal cavity

26 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

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

28 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

29 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

30 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

31 Germination of Zygote

32 Pictures google.com