Parts of the Plant and Their Functions

By: Ita Rodríguez3rd Grade

Importance of plants

• Without plants life on earth would not exist

Plants• Primary source of

food for people and animals

• Produce oxygen• Help keep us cool• Renew (filter) the

air

Plants

• Slow wind speed

• Provide a home for wildlife

• Beautify surroundings

• Perfume the air

• Provide building materials and fuel

Plants

• Need nutrients

• Soil

• Water

• Sunlight

Plant Photosynethesis

• Photosynthesis is the process by which plants make food (sugar or glucose)– Sunlight provides energy– The air provides carbon

dioxide– Nutrients and water are

absorbed by the roots– Photosynthesis occurs in the

chloroplast in the leaves– Sugars are made as food for

the plant and oxygen is released

Carbon dioxide enters the leaves through stomata (tiny holes) in the leaves. Oxygen leaves the same way.

Nitrogen – growth, photosynthesis

Phosphorus – photosynthesis, flowering

Potassium – build proteins, prevent disease

Calcium – strong cells

Magnesium – photosynthesis

Sulfur - build proteins and produce food

Soil Nutrients

Parts of a Plant

• Four basic parts– leaves

– stems

– roots

– flowers

Leaves• Definition: flattened

outgrowth of stem• Used for:

photosynthesis, respiration, and transpiration

• Produces food used by the plant and also store it for later use

Shape and Size of Leaves

• Vary among plants

• Used for identification of plants

•Leaf Base•Petiole•Lamina (blade)•Midrib•Veins•Margins (edges)

Leaves: Their Basic Parts

EXTERNAL ANATOMY

•Part attached to the stem or branch•Protects a bud in its axil

Leaf Base

• Part of leaf that connects the lamina with the stem (leaf stalk)•Some time a leaf may not have a petiole, such leaves are called – Sessile

Petiole

•The flat, expended, and broad part of leaf•Most important part of the leaf (food manufacturer)

Lamina (blade)

• Has veins• Forms structural

framework of the leaf

Midrib

• Large center vein from which all other leaf veins extend

Veins• Systems of tubes

(xylem and phloem) for the transport of nutrients and water– Xylem: ducts that bring

water and minerals from the roots into the leaf

– Phloem: ducts that usually move sap, with dissolved sucrose, produced by photosynthesis in the leaf, out of the leaf

Venation Types

Netted or Reticulate Venation

Margins

• Edges of leaves

• Assists in plant identification

Leaf Arrangement

• Alternate• Opposite

• Whorled– arranged in a

circle around the stem

Leaf Types • Simple leaf:

undivided blade with a single axillary bud at the base of its petiole

Leaf Types • Compound leaf:

blade divided into leafletshas a single bud at the base of its petiole – pinnate -- palmate

Leaf Types

• Peltate leaves: petioles that are attached to the middle of the blade

• Perfoliate leaves: sessile leaves that surround and are pierced by stems

Specialized or Modified Leaves• Cotyledons• Tendrils • Shade leaves • Drought-resistant leaves• Prickles and thorn • Storage leaves• Reproductive leaves• Insect-trapping leaves• Bracts• Window leaves• Flower pot leaves

Cotyledons or “Seed Leaves”

•First leaves produced by a germinating seed•Often contains a store of food to help the seedling become established

Tendrils

Garden Pea

•Leaflets are reduced in size•Allows plant to cling to other objects

Leaves: Needles and Spines

Drought Resistant leaves

Leaves: Colorful Bracts

Petal-like leaves

Internal Leaf Structure

• Epidermis–skin of the leaf

–single layer of cells

–protects leaf from loss of too much moisture

Internal Leaf Structure

Stoma

• Small hole• Opened and

closed by 2 guard cells

• Allows the plant to breathe and transpire– gives off

moisture

open closed

Stoma Function: gas exchange in the leaf

Carbon dioxide

oxygenGuard cell

When a plant is photosynthesising

Leaf Cell (Palisade)

Chloroplasts

• Contains chlorophyll

• Located inside the food making cells

Photosynthesis• Process by which

CO2 and H2O in the presence of sunlight are converted to sugar and oxygen

• This makes the plants' food

Respiration• Plants respire 24 hours a day• They consume O2 and nutrients and

give off CO2 and water

Stems

• Have two main functions– movement of

water and minerals from the roots upward

– movement of manufactured food down

Stem Functions

• Support of leaves and reproductive structures

Stem Functions• Used for food storage

and reproduction of plants involving cuttings

• Green stems manufacture food just as leaves do

External Stem Structure• Lenticels:

breathing pores

• Bud scale scars: indicate where terminal bud has been located previous year

Leaf Scars• Show where leaf

was attached

• Distance between the two represents one year of growth

Internal Stem Structure• Phloem- bark, carries manufactured foods down• Xylem- wood, carries water and minerals up• Cambium- separates the 2 and produces all new

cells

Roots• Underground or

above ground• Functions:

– anchor plant and hold upright

– absorb water and minerals form soil and conduct to stem

– store food

External• Root Cap

– produces new cells– protects roots as they

push through soil• Root Hair

– increases surface area of roots

– facilitate the absorption of water and nutrients

Root Structure

• Internal– similar to stems

– older roots have xylem, phloem and cambian

Type of Root Systems

• Fibrous Roots:

– easier transplanting

– shorter, smaller, more compact

Examples of plantswith this root system are Banana Coconut Rice Corn Sugar CaneAll grasses

Type of Root Systems

• Tap Roots:

– large central roots with shorter, branching roots

Examples of plantswith this root system areMangoAvocadoCarrotsTomatoesPeppers

Type of Root Systems

• Aerial Roots:– hang down in

mid-air and absorb water from rainfall

Examples of plantswith this root system areSome mangrovesWild PineOrchids

Specialized Root Systems

• Stilt Roots:

– grow down from lateral branches, branching in the soil

Specialized Root Systems

• Adventitious Roots:

– Grow from unusual places on plants such as stems, leaves and even fruits

Specialized Root Systems

• Stilt Roots:– grow down from

lateral branches, branching in the soil

Flowers• Definition: the seed-bearing part of a

plant, consisting of reproductive organs (stamens and carpels) that are typically surrounded by a brightly colored corolla (petals) and a green calyx (sepals)

• Vary in size, shape, and colors

• Flowering plants are called angiosperms

Flower Structure• Petals• Stamen and pistil:

reproductive organs

• Anther and ovary• Calyx (sepal):

green leaf-like part that covers and protects bud before opening

Petals• Are actually leaves

• Usually bright colors to attract pollinating insects

Stamen

• Stamens

– male part of flower

– has two parts

1.filament

2.antherFilament

Anther

Pistil• Stamens

– female part of flower– has three parts

1.stigma2.style3.ovary

Anther

• Anther: sac-like structure on top of filament, contains pollen

Ovary

• Egg cells develop here

• Grows to become fruit or seedcoat

Animals: A Simbiotic Relationship

• Pollination: color of flower attracts insects to fertilize flower– beginning of fruit

and seed formation• Fruits and seed are

attractive to birds who eat and spread seeds– reproduces plant– some seeds carried

on animals coats

Types of Flowers

• Complete contains 4 main parts

• Incomplete does not have all 4 main parts

Flower Classification• Monoecious

– stamens and pistils are found in separate flowers on the same plant

– ex: Corn

Flower Classification• Dioecious

– stamens and pistils are found in separate flowers on separate plant

– ex: Holly

Gymnosperms• Group of non-flowering,

seed-producing plants:– conifers, cycads, Ginkgo,

and Gnetales

– comes from the Greek word gymnospermos, meaning "naked seeds"

– seeds develop either on the surface of scales or leaves, often modified to form cones, or at the end of short stalks

Pteridophyta

• Primitive plant• Do not produce flowers

or seeds• Reproduce by spores• Have xylem and phloem

(making them vascular plants)

• Have stems, leaves, and roots

SeedsSeeds

A seed is an embryonic plant enclosed

in a protective outer covering called

the seed coat, usually with some

stored food

External Seed StructureExternal Seed Structure

Seed Coat

• Cactus seed under a powerful microscope

Seed Coat TextureSeed Coat Texture

Internal Seed StructureInternal Seed Structure

Different Types of Seeds

GERMINATIONGERMINATION

Steps:• Seed coat breaks• Radicle becomes

root• Hypocotyl and

epicotyl become the stem

• First leaves grow and photosynthesis begins

First leaves

Watch the following video https://www.youtube.com/watch?v=oYzXToyEzBU

Life CycleLife Cycle

THE END