Botany

1. Plant
Diversity-
Structure and Reproduction of Cycas
Dr. T. Sellathurai
Assistant Professor in Department of Botany

2. Plant
Diversity

3. Biodiversity
 Number, variety and variability of living organisms in natural place
Plant Diversity
 At plant level

4.  Plant diversity
 Angiosperms
 Gymnosperms Monocot Dicot

 Pteridophyta
Bryophyta
Thallophyta

5. 
Diversity of Plants
Plant Diversity (World) India
Algae - 21, 000 sp - 7, 175 sp
Fungi - 1,00 000 sp - 14,500 sp
Lichens - 15,000sp - 2,223 sp
Bryophytes - 24,000 sp - 2,426 sp
Pteridophytes - 10,500 sp - 1,200 sp
Gymnosperms - 725 sp - 67 sp
Angiosperms - 2,50,000 sp - 17,527 sp

6.  Uses plant parts

7.  Structure of Cycas
 Gymnosperm
 At least 200 million years ago
 Triassic & Jursic periods
 Sporophytic nature – 100 species
 Tropical / temperate regions of the world
 Xerophytic characters
 C.circinalis, C. pectinata, C. rumphii,
 C. revolute C. siamensis in Indian garden
 Palm- like evergreen plant
 Compound leaves – cricinate venation
 Trunk – columnar



8.  Cycas
 15 species
 Jurassic &
 Upper Triassic periods
 Fossil (Palaeocycas)

9.  Geological time scale

10.  Cycas circinalis Cycas beddomei
 Cycas pectinata
 Cycas revoluta Cycas rumphii

11.  Distribution in World
 In India

Central America
South Africa
Eastern Asia
India
Australia

12.  Dioecious (separate plant)
 Microsporangium- Male cone
 Conical shape
 Microsporophylls
 Micropsporangia
 Micropsore
 Pollen grain
 Megasporangium -Female cone
 Megasporophyll
 Megaspore - Ovules
 Fertilization
 Ovules - Seed
 Fleshy at maturity
 Bright orange coloured

13.  Microsporangium
 Development
 Eusporangiate- periclinal
 Sporogenous tissue
 Micropsore mother cells
 Micropspore or pollen grains
 As a gametophyte


14.  Male Gametophyte
 Micropsore
 Germination
 Prothallial cell,
 generative cell
 Tube cell
 By Anemophyllous
 Settle on megaspore
 Pollination drop - mucilage
 Micropylar
 4 month
 Penetrates archegonium
 Two sperm
 Chili 5-6 spiral bands

15.  Female gametophyte
 Nucellus
 Megaspore mother cell
 Four haploid megaspore
 Functional megaspore
 Mitotic division
 Free nuclei
 Female gametophyte
 Archegonium
 superficial cell
 Two neck cells
 Central cell
 Venter canal cell
 Egg

16.  Cycas- Female gametophyte (Cross section)


17.  Fertilization
 Pollen grain or micropsore
 Germination of pollen grains
 Pollen tube formation
 Release the sperms
 Reaches up to egg
 Fusion with egg
 Diploid
 Oospore or zygote

18.  Embryo developments
 Oospore or Zygote
 Free nuclei
 Central vacuoles
 Pro-embryo
 Plumule – cotyledons
 Radicle –root
 Seed
 Orange red in coloured
 Testa- coloured
 3 layered
 Embryo in endosperm
 Plumule
 Radicle
 Two Cotyledons
 Germination
 Favourable condition
 Radicle comes out
 Cotyledons not come out
 When the endosperm is exhausted
 Cotyledons dry up
 Plumule comes out with few leaves


19.  Life cycle of Cycus

20.  Economic Importance's
 1. Sago production – Japan
 2. Preparation of alcohol
 3. Juice from young leaves for
 Skin disease, Vomiting of blood,
 stomach disorders
 4. Ornamental purposes
 5. Wood used for boxes and
 Dishes
 6. Baskets and mates

21. Thank You

22.  References
 Indu Varshneya, 2009. Objective Biology ‘ Unique Gateway
PMT’ Unique Publishers, New Delhi-110 024.
 Kumar Pushkar and P. Singh, 2013, CSIR,UGC,NET/JRF/SET
Life Science ( Paper I&II) Upkar Prakashan, Agra – 02.
 Pandey, 2010. College Botany (Vol. III), Chand & Company
LTD. Ram Bangar, New Delhi 110 055
 Sharma, O. P., 2010. Gymnosperms, Pragati Prakshan,
Meerut.
 Shukla, R.S and Chandel, P.S 2012. A Textbook of Plant
Ecology, S. Chand & Company LTD, Ram Nagar, New Delhi
– 110 055.
 Singh, Pande, Jain, 2010. A text book on Botany, Rastogi
Publication, Meerut.