LecturePLANTS TISSUES

Authors as. Kernychna I.Z.

Plan1.Meristematic tissues.

2. Dermal tissues.3. Secretory tissues.

4. Parenchyma.

In the body plants cells not isolated, but placed groups - on the basis of community of origin, structure and functions. These groups of cells name tissues.

Many classification

Living and dead;meristematic and constant;Simple and complex;Primary and secondary

The tissues of a plant are The tissues of a plant are organized into three tissue organized into three tissue systems: the dermal tissue systems: the dermal tissue system, the ground tissue system, the ground tissue system, and the vascular system, and the vascular

tissue systemtissue system

Classification

tissues

Simple tissues are:Simple tissues are: Parenchyma

Chlorenchyma Collenchyma

Sclerenchyma Complex tissues are:Complex tissues are:

DERMALDERMALXYLEMXYLEM

PHLOEMPHLOEM

Meristematic tissues:

the cells are small,

the cells walls are thin,

cells have large nuclei,

vacuoles are absent or very small, and

there are no intercellular spaces.

Plants have four types of meristems: apical, lateral, intercalary, and wound

(or regeneration).

Dermal tissues cover the plant body

There are two types of There are two types of dermal tissuedermal tissue::

The primary is:The primary is:epidermisepidermis

The secondary is:The secondary is:peridermperiderm

Epidermis is closely packed,

without intercellular spaces

or chloroplasts. The outer walls

may be covered waxy, waterproof

cuticle

Guard cells contain chloroplasts and regulate gas exchange between the inside of the leaf and the surrounding air.

Trichomes- on plants are epidermal outgrowths of various kinds.

Trichomes may be unicellular

or multicellular,branched or unbranched

Branched hairs can be dendritic

(tree-like), tufted, or stellate (star-shaped).

Epidermal hairs lower water loss by decreasing the flow of air over the plant surface, which in turn, slows the loss of water from the plant.

Glandular hairs (secretory) prevent herbivory by storing substances that are harmful to insects.

Root hairs increase water uptake by increasing the surface area of the cell.

Epidermis is short lived in many plants. When epidermis ruptures a secondary dermal

tissue periderm that concist of phellogen (cork cambium),phellem (cork),

phelloderm (secondary cortex) replaces it.

SECRETORY TISSUES OF PLANSSECRETORY TISSUES OF PLANS secretory structures: secretory structures:

external secretory structures (nectaries, hydathodes, secretory hair)external secretory structures (nectaries, hydathodes, secretory hair)- internal secretory structures- internal secretory structures

(secretory cells, canals, ducts, cavities, laticifers).(secretory cells, canals, ducts, cavities, laticifers).

Resin canalsResin canals

Internal secretory structure:- - laticiferslaticifers ( (ofof danteliondantelion););

OIL CANALS

ParenchymaParenchyma

Types parenchymaTypes parenchyma

1. Chlorenchyma1. Chlorenchyma2. Aerenchyma2. Aerenchyma

3. Storage parenchyma3. Storage parenchyma

Chlorenchyma

: contains chloroplasts and functions in photosynthesis

Chlorenchyma of leaves

STORAGE STORAGE PARENCHYMPARENCHYM

AA:: characterizecharacterize

d by large d by large accumulatioaccumulatio

ns of ns of storage storage

products products such as such as starch, starch,

protein, oil, protein, oil, hemicellulohemicellulose or water.se or water.

Aerenchymacontains large intracellular air spaces and functions in gas exchange.