Intro to HorticultureIntro to Horticulture

Parts of the plant and their Parts of the plant and their functionsfunctions

By Ryan Talton

Georgia Ag Ed Curriculum Office

May 2004

Functions of leavesFunctions of leaves

..1. Critical for photosynthesis (the process by which plants produce their food).

2. Aid in the process of transpiration which is necessary in order for plants to cool themselves.

4. Sometimes, leaves can be used in asexual or vegetative propagation.

3. Leaves can store some food which can later be transferred to other areas of the plant.

External Leaf StructuresExternal Leaf Structures

Leaves are consist Leaves are consist of petiole and of petiole and bladeblade– Blade is comprised Blade is comprised

of veins and a of veins and a midribmidrib

The veins of the The veins of the leaf form its leaf form its structural structural frameworkframework

..

Internal Leaf Internal Leaf StructuresStructures

EpidermisEpidermis– CuticleCuticle

Waxy substance covers the leaves and stemsWaxy substance covers the leaves and stems Waterproof layer that keeps water in plantsWaterproof layer that keeps water in plants

Principal Tissues of Principal Tissues of the Leafthe Leaf

Epidermis (cont)Epidermis (cont)– StomataStomata

Openings in the epidermis mainly located on Openings in the epidermis mainly located on underside of leavesunderside of leaves

Exchange of gasesExchange of gases

•Guard Cells•Two cells located on each side of stomata•Open and closes stomata

ChloroplastChloroplast

Cells in the center of the leafCells in the center of the leaf The chloroplast contains chlorophyll The chloroplast contains chlorophyll

which gives the plants the green which gives the plants the green colorcolor

Manufactures food for the plant Manufactures food for the plant though Photosynthesisthough Photosynthesis

Beginning of the food chain for all Beginning of the food chain for all living thingsliving things

PhotosynthesisPhotosynthesis

Food manufactured by this process goes down to the roots Food manufactured by this process goes down to the roots thought the stem. It is either used by the plant or stored as thought the stem. It is either used by the plant or stored as a starch, sugar, or proteina starch, sugar, or protein

CARBON DIOXIDE + WATER + LIGHT ENERGY = GLUCOSE + OXYGENCARBON DIOXIDE + WATER + LIGHT ENERGY = GLUCOSE + OXYGEN

RespirationRespiration

Plants respire 24 hours/day just as Plants respire 24 hours/day just as animalsanimals

In this process they consume oxygen In this process they consume oxygen and give off oxygenand give off oxygen

What is the purpose of the What is the purpose of the stems?stems?

Two main FunctionsTwo main Functions– The movement of materials- water, The movement of materials- water,

minerals, foodminerals, food– Support the leaves and reproductive Support the leaves and reproductive

structuresstructures Can be used for food storageCan be used for food storage

– Ex. Irish potatoEx. Irish potato

What are the types of What are the types of stems?stems?

1) 1) Woody StemWoody Stem: trees, shrubs, : trees, shrubs, woody perennialswoody perennials

2) 2) Grass StemGrass Stem: hollow or filled: hollow or filled3) 3) Herbaceous StemHerbaceous Stem: like : like

woody but softer (clover, alfalfa)woody but softer (clover, alfalfa)4) 4) Modified StemModified Stem::

Types of Modified StemsTypes of Modified Stems

BulbsBulbs: (onion): (onion) TubersTubers: (potato): (potato) StolonsStolons: above ground runner : above ground runner

(strawberry)(strawberry) RhizomesRhizomes: below ground runners : below ground runners

(field bindweed or creeping jenny)(field bindweed or creeping jenny)

What is the Terminal Bud What is the Terminal Bud for?for?

Terminal bud tries to make Terminal bud tries to make plant grow taller or longerplant grow taller or longer

if we remove terminal bud, if we remove terminal bud, the plant will be shorter the plant will be shorter and thickerand thicker– Can you think of why we Can you think of why we

would want to do this??would want to do this??– What kind of plants could we What kind of plants could we

do this on??do this on??

Internal Stem StructureInternal Stem Structure

What does the Xylem CarryWhat does the Xylem Carry– Water and minerals travel up Water and minerals travel up

What about the PhloemWhat about the Phloem– Manufactured food travels down the Manufactured food travels down the

plantplant What does the Cambium do?What does the Cambium do?

– Separates the xylem and the phloemSeparates the xylem and the phloem– Thin, green, actively growing tissue Thin, green, actively growing tissue

located between the bark and the located between the bark and the wood of a plantwood of a plant

What is the difference in What is the difference in monocot and dicot and why monocot and dicot and why

should I care?should I care? Dicot stem may continue to increase in Dicot stem may continue to increase in

diameter because the cambium builds new diameter because the cambium builds new phloem cells on the outside and new phloem cells on the outside and new xylem cells on the insidexylem cells on the inside– Ex. TreesEx. Trees

Monocot have vascular bundles which Monocot have vascular bundles which contain both xylem and phloem and no contain both xylem and phloem and no cambiumcambium– This would make it more limited in sizeThis would make it more limited in size

Ex. cornEx. corn

Why should we care?Why should we care?

The stems of some The stems of some plants we use as plants we use as foodfood– Irish potato and Irish potato and

asparagusasparagus Others are used in Others are used in

building materialsbuilding materials– Lumber from the Lumber from the

tree trunkstree trunks

RootsRoots

Roots functionRoots function– Anchor the plant and hold it uprightAnchor the plant and hold it upright– Absorb water and minerals from the soil Absorb water and minerals from the soil

and conduct them to the stemand conduct them to the stem– Store large quantities of plant foodStore large quantities of plant food– Propagate or reproduce some plantsPropagate or reproduce some plants

Fibrous root vs. tap rootFibrous root vs. tap root

Fibrous root systemFibrous root system– Much easier to transplantMuch easier to transplant– More spread outMore spread out

Tap root systemTap root system– Longer fewer rootsLonger fewer roots– End of root contains many root hairsEnd of root contains many root hairs

Functions of Fruit:Functions of Fruit:

1. Protect the seeds inside the ripened ovule (fruit).

2. Provide nutrients to the soil and to a newly germinated seedling.

3. Aid in the dissemination/spreading of seed by providing food for animals.

Animals eat the fruit and seeds. After the fruit is digested, the seeds pass out in the

animal’s feces at another location.

4. Some plants have dry, dehiscent fruitswhich split open to disseminate seeds.

What is the purpose of What is the purpose of seedsseeds

To continue the plant processTo continue the plant process There are two typesThere are two types

– MonocotsMonocots– dicotsdicots

Monocot and dicotMonocot and dicot