Parts of the plant and their functions

Importance of plants

• Without plants life on earth would not exist

Plants:

• Primary source of food for people and animals

• Produce oxygen

• help to keep us cool

• renew the air

Plants:

• slow wind speed

• provide a home for wildlife

• beautify surroundings

• perfume the air

• furnish building materials and fuel

Parts of a plant

• Four basic parts–leaves

–stems

–roots

–flowers

Leaves

• the food factory of the plant

• produce the food used by the plant or stored for later use

Shape and size of leaves

• vary among plants

• used for identification of plants

Leaf arrangement

• alternate

• opposite

• whorled–arranged in a circle around the

stem

External leaf structure

• petiole - leaf stalk

• leaf blade (leaf)–has veins

–forms structural framework of the leaf

Midrib

• large center vein from which all other leaf veins extend

Margins

• edges of leaves

• assists in plant identification

Internal leaf structure

• epidermis–skin of the leaf

–single layer of cells

–protects leaf from loss of too much moisture

Guard Cells

• open and close the small pore on the underside of the leaf

Stomates

• allow the plant to breathe and transpire–give off moisture

Chloroplasts

• contain chlorophyll

• located inside the food making cells

Photosynthesis

• process by which CO2 and H2O in the presence of light are converted to sugar and oxygen

Chemical formula

• 6CO2 + 6H2O

• -----> in reaction with sunlight and chlorophyll ------>

• C6H12O6 (glucose) + 6O2

food

• manufactured in the leaves moves downward through the stem to the roots–used by the plant

–stored in stem or root and leaf in the form of sugar, starch or protein.

Respiration

• plants respire 24 hours a day

• consume O2 and give off CO2

• plants produce more O2 through ps. Than they consume during respiration and growth.

Stems

• have two main functions–movement of water and minerals

from the roots upward and movement of manufactured food down

Stem functions

• support of leaves and reproductive structures

Stems also

• 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

• shows 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.

• Characteristic of dicots

Internal Stem Structure

• dicot- dicotyledon, a plant with 2 seed leaves

Monocot

• Monocotyledon - a plant with one seed leaf.

• Have vascular bundles, contain both xylem and phloem in each small bundle

Monocot

• stems have no cambium

• cells enlarge to create size of mature stem

Economic Importance

• food

• building materials

Roots

• Usually underground• functions:

–anchor plant and hold upright–absorb water and minerals form

soil and conduct to stem–store food, & propagation

Root Structure

• internal

–similar to stems

–older roots have xylem, phloem and cambian

external

–root cap

•produces continuous supply of new cells

•protects roots as they push through soil

Structure

• root hairs

–absorb moisture and minerals

• small roots

Functions other than water and mineral absorption

• cash crops for food

–carrots

–beets

–radishes

–sweet potatoes• propagation

Type of root systems

• fibrous-grasses

–easier transplanting

–shorter, smaller, more compact

• lap root-carrot

–longer and fewer roots

Flowers, Fruits, and Seeds

• 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

Parts of the Flower

• differ in size, shape, and color, some basic parts

• sepal

–green leaf-like part, covers and protects bud before opening

Petals

• are actually leaves

• usually bright colors to attract pollinating insects.

Parts of the Flower

• stamens

–male part of flower

–has two parts

•filament-stalk

Anther

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

Parts of the Flower

• Pistil - female part

• in the center of flower

• has three parts

Pistil

• three parts

• stigma - top - sticky

• style - tube leading from stigma to ovary

Ovary

• egg cells develop here

• grows to become fruit or seedcoat

Types of Flowers

• complete

–contains 4 main parts

Incomplete

• does not have all 4 main parts

Perfect

• has stamens and pistils

Imperfect

• lacks stamens or pistils

Types of Flowers

• monoecious

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

•ex: Corn

dioecious

• male or staminate flowers found on one plant, female or pistilate flowers on another plant

• ex: holly