ANATOMY OF FLOWERING PLANTS

Anatomy : Study of internal structure.

Tissue : Group of cells performing common function
1) Meristematic Tissue / Meristem : Undifferentiated & Actively dividing cells
a) Primary meristem : Appear on Early life of plant - Produce immature/1 plant body.
 Apical meristem : Occur on  Axillary bud : SAM cells  Intercalary meristem :
tips of shoots (Shoot AM) that are left behind during Located on internodes.
& roots (Root AM) the elongation of stem Responsible for regrowth


Help in growth from tip /

 Present in the axis of leaf.
 of plants after cut.
elongation Responsible for formation


of new branch
b) Secondary/Lateral meristem : Appear on later life of plants – Produce mature/2 plant body.
 Vascular cambium  Cork cambium

2) Permanent / Mature tissue : Differentiated cells that hav lost the ability to divide.
a) Simple tissue : Permanent tissue formed by cells of same type.
 Parenchyma(living) : Isodiametric cells packed with intercellular spaces
Thin wall made of cellulose


Function : Photosynthesis(hav chloroplast), Food storage…



 Collenchyma(living) : Tightly packed cells without intercellular spaces

 Thick walls due to deposition of cellulose, hemicellulose & Pectin.
 Function : Mechanical support to young growing parts & leaf petiole
 Sclerenchyma(dead without protoplasm) : Cell wall is thick & lignified with numerous pits
 Seen on fruit wall of nuts, pulp of fruits Function : Mechanical support to organs
like guava, pear and sapota; seed coats - Fibers : Elongated narrow sclerenchyma
of legumes and leaves of tea - Sclereids : Spherical Sclerenchyma

b) Complex Tissue : Permanent tissue formed by many different types of cells.

 Xylem : Conduct water & minerals from root to leaves.
 It have 4 components.
 Xylem Tracheids : Narrow tube like dead cells - Function : Transport
- Thick lignified cell walls
 Xylem vessels (Absent in gymnosperms) : - Have Large central cavity
- Cylindrical tube like structure made of many - Vessels members are interconnected by
dead cells called vessel members. perforations in their common wall
- Thick lignified cell walls - Function : Transport
 Xylem fibers : (Same as Sclerenchyma fiber)
 Xylem Parenchyma (Same as parenchyma)

Protoxylem First formed xylem Endarch Protoxylem at centre(pith) & Seen in stem
(During 1 growth) arrangement metaxylem at periphery
Metaxylem Later formed xylem Exarch Protoxylem at periphery & Seen in root
(During 2 growth) arrangement metaxylem at centre
 Phloem : Transport food in plants : Have 4 components
 Sieve tube elements : Long tube like cells with peripheral cytoplasm, large vacuole & lack a nucleus.
- Their walls are perforated in sieve-like manner to form sieve plates.
 Companion cell : Parenchymatous cell with a nucleus.
- They are connected with sieve tube by pit fields present b/w
their common longitudinal wall.
- Control pressure gradient & other functions of Sieve tube.
Gymnosperms have albuminous cells & sieve cells instead of sieve tubes & companion cells.
 Phloem Parenchyma : Elongated parenchymatous cells.(absent in some monocots)
- Store food & other substances like resin, latex…. Proto 1st formed Hav narrow
 Phloem fibers/Bast fibers : Sclerenchyma fibre phloem phloem sieve tube
- Phloem fibres of jute, flax & hemp hav commercial use. Meta Later formed Hav big
phloem phloem sieve tube
TISSUE SYSTEM : Classified based on location.
1) EPIDERMAL TISSUE SYSTEM
2) GROUND TISSUE SYSTEM
3) VASCUALR TISSUE SYSTEM

1) EPIDERMAL TISSUE SYSTEM :Outermost covering of plant body.

a) Epidermis : Outermost, parenchymatous continuous & single layered cells of 1 plant body.
Cuticle : Waxy layer covering epidermis (except stomatal opening) – Prevent water loss.
b) Stomata : Pores on epidermis specialized for shrink & close the pore
transpiration & gas exchange.  Guard cells are either bean shaped (dicot) or
 Guard cells : 2 cells guarding the pores – Their dumbbell shaped (monocot)
outer walls are thick & inner walls are thin.  Subsidiary cells : Cells around guard cells ->
 When water enter in guard cells -> They imbibe They control functions of guard cell.
& open the pore.  Stomatal Apparatus : Stomatal pore + Guard
 When water leave from guard cells : They cells + Subsidiary cells.

c) Root hair : Unicellular elongations of epidermis seen on root.

: Help in absorption.
d) Trichomes : Multicellular elongations of epidermis seen on stem.
: Prevent water loss due to transcription.

2) VASCULAR TISSUE SYSTEM : Include Xylem & Phloem (Explained earlier)

 Cambium: Ring of active cell division seen b/w 1 Xylem & phloem of dicot stem.
 It help in 2 growth (2 thickening)
 It cut or divides the cells to both outside & inside of cambial ring.
 The cells that added to inside become 2 Xylem & The cells that added to outside become 2 Phloem
TYPES OF VASCULAR BUNDLE
Radial V B Xylem & Phloem arranged in alternate Eg : Roots
manner along diff radii

Conjoint VB Xylem & Phloem jointly situated along Eg : Stem &

same radius. leaves

Open conjoint Cambium present b/w Xylem & Phloem - Eg : Dicot stem
> Do 2 growth
Closed conjoint Bo cambium b/w vascular bundles -> No Eg : Monocot
2 growth stem

2) GROUND TISSUE SYSTEM : Tissues that neither dermal nor vascular.

 Present in cortex, pericycle, pith and medullary rays( in stem & roots) & Mesophyll cells in leaves
 Formed of parenchyma, collenchyma and sclerenchyma.

ROOT - ANATOMY
Layers Dicot(a) Monocot(b)
Epiblema/ Single layered – Hav root hairs
Epidermis
Cortex Multi layered - Parenchymatous
Endodermis  Single layered, barrel shaped cells
 No intercellular spaces
 Casparian strips : Cells of epidermis having waxy
Suberin deposition.
: Make the cells impermeable to water
Stele
a) a)Pericycle Thick walled, Parenchymatous cells
b)Vascular 2-4 in number 6 in number
bundle Open, Radial, Exarch Closed, Radial, Exarch
c)Conjunctive Parenchymatous tissue Absent
tissue b/w Vascular tissue ->
It forms cambium
d) Pith Central

STEM ANTOMY
Layers Dicot Monocot
Epidermis Hav cuticle, trichome, stomata Hav cuticle only
Cortex – Hav 3 subzones
a)Hypodermis Collenchymatous Sclerenchymtous
b)Cortical layer Parenchymatous All these layers are absent.
c)Endodermis Starch rich – So form starch sheath Space is filled with ground tissue.
Pericycle Formed of semilunar patches of
schlerenchyma Sclerenchymatous bundle sheath is seen
Medullary rays Parenchymatous tissue b/w vascular on the outside of a vascular bundle.
bundle -> Form cambium
Vascular bundle Conjoint, Open, Endarch Conjoint, Closed, Endarch
Arranged as Ring Scattered arrangement
Pith Central Absent
LEAF ANATOMY
Layer Dorsoventral / Dicot leaf Isobilateral/ Monocot leaf
Epidermis Covers adaxial & Abaxial surface - Hav cuticular covering
Abaxial Epi hav more stomata Equal stomata on both sides
Bulliform cells are seen.
Mesophyll Parenchymatous tissue filled b/w ada & aba epidermis
cells Hav chloroplast – Do photosynthesos
It is divided into 2 Mesophyll cells are not differentiated
into palliside & spongy
a)Palliside Elongated & Compact
parenchyma Seen near adaxial side
b)Spongy Round & loosely arranged cells
parenchyma Seen near abaxial side
Vascular Seen as vein/midrib & veinlets
tissue Surrounded by bundle sheath cell

Bulliform cells : Large, empty, color less cells formed by modification of epidermal cells
When they get turgid by absorbing water -> Leaves are exposed
When they get flaccid due to water stress -> Leaf curl inwards -> Minimize water loss.