1st PUC biology- ANATOMY OF FLOWERING PLANTS notes- descriptive

ANATOMY OF FLOWERING PLANTS-

1.       Tissue-

a.        a group of cells performing the similar functions

b.      They are of 2 types in plants- meristematic and permanent tissues

2.      Meristematic tissue- are specialized cells present in the regions where active cell divisions are necessary. They are of 3 types

a.       Apical meristems- present at the apex of root and shoot

i.                    Root apical meristem present at the tip of the root

ii.                  Shoot apical is present in the shoot apex

iii.                Few meristems are left behind and they form axillary bud- helps in leaves formation. Branches

b.      Intercalary meristems- present between the mature tissue, generation of grasses when fed by herbivores

Apical and intercalary meristems=primary meristematic tissue

c.       Secondary or lateral meristems- present in mature root and shoot, produces woody axis also called as cylindrical meristems.

Ex- vascular cambium, cork cambium, interfasicular cambium

3.       Permanent tissue- when the following meristems lose there cell division ability they become permanent tissue. They are divided in to simple and complex tissue-

a.       Simple tissues-made of only 1 type od cells, they are

i.                    Parenchyma-major component of the plant, isodiametric shape to oval, spherical…thin cell wall, made of cellulose, small intercellular spaces, storage, photosynthesis and secretion

ii.                  Collenchyma-present below epidermis in dicots, thickened corners deposited by cellulose, hemicellulose and pectin. Oval, spherical or polygonal. May have chloroplasts, no intercellular spaces, mechanical support in young stem and leaf petiole

iii.                Sclerenchyma- long, narrow, thick, lignified cells with many pits. Dead cell- no cell organelles. Two types- fibres-thick cell wall, elongated, pointed ends, present in groups… sclereids- spherical, oval, cylindrical highly thickened, narrow open- cavity, present in fruit walls nuts, pulp of fruits, …… provides mechanical support

b.      Complex tissue-made of more then one type of cells- xylem and phloem

i.                    Xylem- water and mineral conducting tissue from roots to stem and leaves. The parts of the xylem are-

A.     Trachieds- elongated tube cell, thick wall coz of lignification, tapering ends, dead cells, transport water

B.      Vessel- long cylindrical tube, made of many vessels, liginified with a centre cavity, dead cell, connected to each other by perforations, seen only in angiosperms

C.      Xylem fibres- thick wall central lumen, septate or aseptate, dead cell

D.     Xylem parenchyma- only living cell, thin cell wall, cellulose, storage of food in form of starch, fat, tannins

ii.                  Phloem- transports food from leaves to all parts of the plants, gymnosperms lackssieve tubes and companion cells

A.     Sieve tube elements- long, tube like, arranged longitudinally, with companion cells, end wall has sieve plates, has peripheral cytoplasm, large vacuole, no nucleus. Its controlled by companion cells

B.      Companion cells- parenchymatous, present with sive tubes, and are connected by pits by longitudinal walls, maintains pressure gradients

C.      Phloem parenchyma- elongated tapering, cylindrical cells, dense cytoplasm, nucleus, cell wall made of cellulose, has pits and plasmodesmatal connection , stores resins, latex and mucilage

D.     Phloem fibres- are sclerenchymatous cells, elongated, unbranched, pointed needle like apices, thick cell wall, dead cells, jute flax and hemp. Protophloem- primarily formed phloem with narroe sieve tube…..metaphloem- later formed phloem with bigger sieve tube

Tissue system- 3 types

Epidermal tissue system	Ground tissue system	Vascular tissue system
Outer most covering of the plant, has epidermal cells, stomata and trichomes and root hairs. Cells- elongated, compact arrangement, parenchymatous, less cytoplasm, large vacuole, thick waxy cuticle outside[absent in roots] Stomata- present on leaves surface, helps in exchange of gases, kidney shaped, inner wall thick outer wall thin, outside has subsidiary epidermal cells Stomatal aperture+guard cell + subsidiary cells=stomatal apparatus Root hair-thin, help in absorption f water and mineral salts Trichomes-multicellular, may or may not be branched, soft/stiff, secretory, prevents transpiration	Ground tissue = epidermis and vascular tissue are absent parenchyma+collenchyma+sclerenchyma, cells- thin chloroplasts are present called mesophyll tissue	Complex tissue- xylem and phloem In dicots- it has cambium b/w phloem and xylem=secrondary growth-open vascular bundles Monocots- no cambium-closed vascular bundles Alternate xylem and phloem-=radial arrangement-stema na dleaves In conjoint they are arranged on the same radius- present in outer xylem

ANATOMY OF DICOT AND MONOCOT PLANT-

Terms-

EPIDERMIS- outermost layer in shoot and root                                CORTEX-made of many layer cells, +nt beneath epidermis till vasculature                 ENDODERMIS-innermost layer of cortex made of 1 type of cells,no intercell spaces                    CASPERIAN THICKENINGS-outer thickenings present on the endodermis, waxy           PERICYCLE- outer layer of the vascular bundle       CONJUNCTIVE TISSUE- parenchyma cells +nt b/w phloem and xylem         STELE=pericycle+vasculature+pith       HYPODERMIS- differentiated cortex, 2^nd layer in the cortex     ENDODERMIS-inner layer of the differentiated cortex                                STARCH SHEATH-starch grains +nt in endodermis                MESOPHYLL- tissue b/w upper and lower epidermis of leaf     PALISADE PARENCHYMA- part of mesophyll, elongated cell,arranged vertically and paralled to each other                  SPONGY PARENCHYMA- part of mesophyll, spherical cells  BUNDLE SHEATH CELLS- thick wall b/w bundle sheath

DICOT ROOT	MONOCOT ROOT	DICOT STEM	MONOCOT STEM
Epidermis is present, many root hair are seen on the epidermal layer, Cortex- parenchymatous cells, many layers Cortex opens to endodermis and then to pericycle Vascular bundle- 4 xylem and phloem arranged alternate Secondary growth is seen coz of the cambium	Same as dicot root but more xylem and phloem bundles- polyarchi No secondary growth	Outer layer epidermis Epidermis covered with cuticle Few stomata, cortex- multilayered in hypodermis-thin cell with spaces and endodermis- with starch grains Pstarch sheath, pericycle +nt,phloem semi lunar patches Vasculature- radially arranged,ricg like. Conjoint, open, endrach protoxylem Pith is present	All are same as dicot Vascular bundles-conjoint, closed peripheral vascular bundles, smaaler Phloem parenchyma -nt
DORSIVENTRAL LEAF		ISOBILATERAL LEAF
Mainly has 3 regions=epidermis, mesophyll, vasculature Epidermis is on upper[adaxial surface-more stomata], lower surface[abaxial – less or no stamata], Mesophyll has palisade and spongy parenchyma Vascular size depends on vein size, size of mid vein varies in reticulate veination Vasculature present in mid ribs and veins		Most of the structure is similar except for the following- +nce of stomata on 2 sides No differentiation in mesophyll Bulliform cells in epidermis[grass]- turgid cells on losing water becomes flaccid there by curling the leaf Same size vasculature coz of parallel veination

SECONDARY GROWTH-increase in the girth of the plant bought by lateral meristem, cork cambium, vascular cambium

VASCULAR CAMBIUM	CORK CAMBIUM	SECONDARY GROWTH IN ROOT
Is because of the xylem and phloem Dicots- they are +nt b/w primary xylem and phloem=intrafascicular cambium Cells b/w medullary ray adjoining them form interfascicular cambium,hence continuous ring formed ACTIVITY OF CAMBIAL RING- Cambial ring becomes active and cuts off towards pith[secondary xylem] and periphery[secondary phloem]. cambium more active inner side secondary medullary rays- a narrow band of parenchyma passing through secondary xylem and phloem spring/autumn wood- spring cambium is active, produce many xylem elements with wide cavities. The wood formed in this season is early wood winter cambium is less active and xylem elements have narrow vessels. This wood is late/autumn wood SPRING WOOD- light color,low density AUTUMN WOOD-dark and high density alternate 2 woods forms annual rings.the annual rings tells us the age of the wood HEART/SAPWOOD-old trees secondary xylem is dark coz of resins, oils, gums, aromatic oils.this substances make the wood hard, durable and resistance, Its made of dead cells, lignified walls-heartwood It doesnot conduct water Mechanical strength, SAPWOOD- light color, conduction of water and minerals	When the plant girth increces the discontinuity is formed which is filled up by meristematic cambium called cork cambium / phellogen- thick layer, narrow, rectangular cell Phellogen cuts in to outer phellem and inner secondary cortex/ phelloderm Cork is impervious to water coz of suberin deposition Phelloderm- parenchyma Coz of this pressure builds and layer die and slough off Bark is made of periderm and phelloderm Early season bark- early/soft bark End season- late/hard bark Lenticels- pores present on the bark allowing cells to breathe and secretion	In dicot vascular completely secondary origin Originate from-tissue below phloem, pericycle, protoxylem thereby forming continuity Further is similar to stem