Plant Tissues And Organs

By: Aldinette C. Esto BSED III – Math Biological Science

Plant Tissues Meristematic Tissue - Growth tissue - Capable of mitotic cell division - cells are similar in structure and have thin and elastic primary cell wall made up of cellulose

Permanent Tissue - More mature cells

- Forms more stable or permanent parts of the plant - “Cellular differentiation”

R.A.M. S.A.M. Api ca l

present at the growing tips of stems and roots

Mer ist em

responsible for growth in length of the plant located in between permanent tissues

increases the length of the stem and root and production of leaves

Me ris te mat ic Tiss ue

Int erc al ar y Meri st em

surround the established stem increases the diameter and girth of the shoot

Lat er al Mer ist em

Cork Cambium Vascular Cambium

Parenchyma Sim ple Collenchyma Sclerenchyma Per ma nent Tissu e Endodermis

Form the protective outer covering of the plant body

Su rfac e Tissu e Epidermis Periderm

Composed of similar types of cells which have common origin and function

Permanent Tissue

Xylem Phloem

Comp lex Per ma nent A group of more than Tissu e one type of tissue having a common origin and working together as a unit to perform a function

Major Plant Organs

Shoot System

Root System

ROOT • FUNCTIONS  Anchorage  Absorption  Storage  Propagation  Photosynthesis

TYPES OF ROOT SYSTEM

Diffuse or Fibrous Root System

Taproot System

LONGITUD INA L SEC TI ON OF THE R OOTS Root Cap “mucigel” Meristematic Region

Elongation Region

Maturation Region

CROSS-SEC TI ONA L V IEW OF TH E ROOTS

Epidermis

Cortex “hypodermis, storage parenchyma and endodermis Pericycle

Vascular Tissues “xylem” and “phloem”

Cross section of root • • • •

Vascular bundle (Stele) = contains xylem and phloem Cortex Epidermis Root hairs

Fig. 38.15

Specialized Roots Adventitio us

Aerating

Coarse

Contractile

Aerial P

Fine P

Haustorial P

Proteoid

Photosynthet Propagative ic P Stilt

Storage P

Structural

Surface

P

Tuberous

P

Adventitious Aerial

Aerating

Contractile

Propagative

Haustorial

Stilt

Storage

Tuberous

SHOOT SYSTEM

STEM • FUNCTIONS OF THE STEM • 1) Support • 2) Conduction • 3) Food Storage • 4) Protection • 5) Propagation • 6) Photosynthesis

Know Stems  Epicotyl – structure that extends from the hypocotyls', where primary stem originates  Soft/Herbaceous stems – soft and green, have small diameters and covered with epidermis, die in a year  Woody stems – tough, not green, can grow considerably in height and diameter and can live for many years  Tree – woody stemmed plant with a single trunk  Shrub – woody stemmed plant with several main stems of the same size, smaller and shorter than trees.

Exter nal S tr uc ture of a Woo dy S te m   

Lenticels – tiny pores for gas exchange Leaf scars – marks left by fallen leaves Buds – masses of meristematic tissues that may result in growth in length or production of leaves/flowers. They can be:       

 

Terminal Lateral/axillary Flower bud Leaf/branch bud Naked bud Covered bud Active/dormant

Bud scales – leafy structures that cover and protect the buds from drying out Bud scars – marks left by fallen buds scales, form a ring around a twig.

Internal Structure of a Woody Stem Bark – outer layer  Cork  Cork Cambium  Cortex  Phloem  Wood/xylem – inner part, contains the annual rings • Annual ring – ring of xylem tissues added during 1 growing season  Spring Wood  Summer Wood • In dicot woody stems, such as in roots, the pith is present. Laterally extending out the pith, are vascular rays. The vascular cambium is found between the bark and the wood. 

Fig. 38.7a

Fig. 38.7b

Structure of a Herbaceous Dicot Stem  Epidermis – similar to woody stems  Cork – absent  Cortex – thinner but similar to woody stems  Chlorenchyma cells – type of parenchyma cells, have chloroplasts and make up the cortex  Stele – same as woody stems  Xylem and phloem – larger in herbaceous dicot stems than in woody stems, separated by vascular bundles  Cambium layer - present, but little

Fig. 38.25a

Structure of a Herbaceous Monocot System Vascular bundles – scattered throughout the stem Cambium layer – absent Closed bundles – vascular bundles of a herbaceous monocot stem Open Bundles – vascular bundles in dicot stems

Fig. 38.25b

MODIFIED STEMS Aboveground

Stolons Tendrils

Cladodes

Thorns

Succulent Stems

Underground

Rhizome s

Bulbs

Corms

Tubers

Wild asparagus

bougainvillea

LEAVES  major sites of photosynthesis  Release moisture through “transpiration”  EXTERNAL Structure  Blade – for absorption  Leaf apex – tip of leaf  Petiole/stalk – attached to node of stem (leaves without petioles are calles sessile leaves)  Midrib – central vein  Leaf margin – edges of a leaf  Stipules – tiny flaps of tissues, perform photosynthesis and ensure pollination

Simple Leaf

Compound Leaves

Internal Structure of a Leaf  Epidermis  Mesophyll – contains chlorophyll rich cells  Palisade layer – below upper epidermis, consists of vertically elongated cells  Spongy Tissues – consists of horizontally elongated cells

MODIFIED LEAVES  Bud scales  Bulb scales  Tendrils  Spines  Bracts  Insect-trapping leaves  Reproductive leaves

Fig. 39.1

FLOWERS  Reproduction  Floral symmetry

Radial or regular symmetry

Bilateral or irregular symmetry

FLOWERS

3 Major Parts: Gynoecium Androecium Perianth

2 Categories: Monoecious dioecious

4 Classifications: Complete Incomplete Perfect Imperfect

POLLINATION • the transfer of pollen (male gamete) from the anther to a stigma Cross-pollination and Self-pollination

Parts of the Flower • Peduncle • Receptacle • Sepal • Calyx • Petal • Corolla • Stamen

Flower stalk. Part of flower stalk bearing the floral organs Leaf-like structures at flower base, protects young flower bud. All the sepals together Located in and above the sepals, often serve to attract pollinators to the plant. All the petals together Male part of the flower

Parts of the Flower • Filament • • • • • • •

The stalk of the stamen which bears the anther. Anther The pollen bearing portion of a stamen. Pollen Grains containing the male gametes. Carpel\Pistil Consisting of the stigma, style and ovary. Stigma serves as a receptive surface for pollen grains. Style The stalk of a carpel, between the stigma and the ovary, Ovary Enlarged base of the carpel containing the ovule or ovules. Ovule Located in the ovaries. Carries female gametes.

Monocotyledon – grasses – lilies, tulips – trees: palm

Dicotyledon – roses, asters – grapes, beans – trees: oak, maple,

Plant Tissues and Organs

By: Aldinette C. Esto BSED III – Math Biological Science