Download Parts of the plant and their functions

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