This PPT contains a birds' eye view of the basic internal organization of the plant body comprising of tissue networks along with tissue systems to perform diverse functions for plants survival even in stress condition.

1. STRUCTURE & DEVELOPMENT OF PLANT
BODY: Internal organization of the plant body
By N.Sannigrahi, Associate Professor,
Department of Botany, Nistarini College,
Purulia(W.B) 723101, India
The complex multicellular body of the seed
plants, a result of evolutionary specialization is
the outcome of a series of gradual developmental
changes for the establishment of morphological
& physiological differences between the various
parts of the plant body. The division,
differentiation, dedifferentiation &
dedifferentiation are the events happen to
establish the present state.

2. Plant Structure

3. STRUCTURE
• Through the life long journey of seed plants, it
experiences two kind of structure-Primary &
secondary.
• Primary-This structure initiates at the juvenile
stage when cotyledonary leaves sprout-giving
rise to plumule & radicle.The former gives rise
to shoot systems & the later gives rise to root
system. Whatever be the story, the three type
of tissues developed- Epidermal, Ground &
Vascular tissues. The epidermal gives the
external coverings, the ground as the transition
& the vascular for vascular supply.

4. Ontogeny repeats phylogeny: Interaction between
Genes & Environment
• With about 250,000 known plant species, the
angiosperms are most diverse plant groups.
• A plant’s structure reflects interactions with the
environment in two time scale .Over long term, the
entire plant species have, by natural selection,
accumulated morphological adaptations that enhance
the survival & reproduction,
• Over short time, the individual plants exhibit
structural responses to their specific environment.
• The architecture of the plant is a dynamic process ,
continuously shaped by plant’s genetically directed
growth pattern( Homeotic genes) along with the fine
tuning with environment.

5. Internal beauty: Pleasure to anatomists

6. Anatomical comparison

7. Inside the wood

8. Secondary Structure
• After enjoying a optimum growth stage, the
secondary development switches on for increasing
the girth of the plant body. This is mediated by
secondary meristematic tissues-Vascular cambium
& Cork cambium. The vascular cambium as
remains within the stealer region popularly brings
intrastealer growth & the cork cambium lies in the
non-stealer region, brings extra-stealer growth.
The intrastealer growth transforms into the
secondary xylem called wood & extra stealer
region transforms the bark or periderm.

9. Wood-the beauty

10. Three tissue systems

11. Epidermal Tissue system
• The dermal tissue or Epidermis is generally a single
layer of tightly packed cells that covers & protects all
young parts of the plants. Single layered very often
interrupted by stomata, continuous layers perform
many functions-
• Covering layer to protect against mechanical injury
• Save evaporation from internal tissues,
• Photosynthesis & secretion
• Storage house of water of xerophytes
• Secretory tissues like nectaries, stomata a etc.
• Stomata of different types trichomes hairs, are some
modifications.

12. Ground tissues
• In between epidermis & Vascular cylinder, cortex
is the ground tissues,
• Mostly thin walled parenchyma tissues but
collenchymas, sclerenchyma and sclerides in
addition to parenchyma tissues
• Very often formed hypodermal regions and starch
sheath
• Endodermis , a barrel shaped cells arranged Act
as protective coverings and to maintain root
pressure, very often storage of starch grains,
• Pericycle & pith also become the part of the
ground tissues.

13. Primary Vascular tissues
• Procambium-the meristematic tissues give
morphological vascular units gives first xylem & first
phloem separated radially by procambium in stems &
leaves and transitionally by promeristem in roots.
• Exarch primary vascular bundles consists of three
major zones-Xylem(Wood), Phloem(Bast) and
cambium
• Xylem-Vessels or tracheae, Trachids, Wood fibers and
xylem or wood parenchyma
• Vessels –annular, spiral, scalariform, reticulate and
Pitted
• Xylem-primary & secondary either Exarch, endarch or
mesarch, it may be protoxylem or metaxylem

14. Phloem
• Phloem-may be proto phloem & metaphloem,
Primary & Secondary phloem,
• Consists of Sieve tubes, companion cells,
Phloem parenchyma & phloem fibers or bast
fibers
• Cambium-Primary & secondary
• Vascular bundles-Radial(roots),
Conjoint(Collateral & Bicollateral), Concentric
• Conjoint Open(Cambium) or closed(No
cambium)

15. Different tissues arrangement

16. Dicot VS Monocot stem

17. Leaf anatomy

18. STELE
• Central vascular cylinder with or without pith and
delimited the cortex by endodermis.
• Protostele, siphonostele,Sloenostele, dictyostele,
Polycxyclic stele & Eustele
• Protostele (Without Pith)- Haplostele, Actinostele
, Plectostele & Mixed pith stele,
• Siphonostele-Medullated contains a tubular
vascular region and parenchymatous central
region-Cladosiphonic (Leaf gaps absent) &
phyllosiphonic (Leaf gaps & branch gaps present)

20. PHLOEM ANATOMY

21. Thank you for your patience to stay with