Download Plant Parts and their Functions

Plant Parts and their
Functions
13.00 Describe principles of plant
science as related to horticulture
14.00 Compare the anatomical parts
and distinguishing characteristics of
horticultural plants
Plant Sciences
• Biology-the branch of science that
deals with both plant and animal
organisms and life processes
– Zoology-the part of biology that deals
with animals
– Botany the part of biology that deals
with plants
Plant Sciences
• Applied plant sciences are based
on the purposes for which the
plants are grown
– Agronomy
– Forestry
– Horticulture
Agronomy
The science and practice of growing
field crops such as cotton, wheat,
tobacco, corn and soybeans.
Forestry
The science and practice of growing,
managing and harvesting trees for
building materials and other
products.
Horticulture
The science and practice of growing,
processing and marketing fruits,
vegetables, and ornamental plants
Life Cycles of Plants
• Annual-a plant that completes its
life cycle in one year
• Biennial-a plant that completes its
life cycle in two years
• Perennial-a plant that lives more
than two years
Leaf Retention
• Deciduous-loses leaves during the
dormant season
• Evergreen-keeps leaves and
remains green year-round
Plant Hormones
• Several types of hormones are
used to help plants work more
efficiently.
– Inhibitors
– cytokinins
– gibberellias
– auxins
Inhibitors
• Inhibitors hasten fruit ripening,
retain seed germination and stem
elongation.
Cytokinins
• Hormones that work with auxins to
stimulate cell division.
Gibberellias
• Hormones that stimulate cell
elongation, premature flowering,
and breaking of dormancy.
Auxins
• Hormones that speed plant growth
by stimulating cell enlargement
Moisture in Plants
• Turgid-plant is swollen or filled
with moisture
• Wilted-plant is limp because it
does not have enough moisture
Plant Parts
•
•
•
•
Leaves
Stems
Roots
Flowers
Leaves-External
• Petiole-leaf stalk or part that
connects the leaf to the stem
• Blade-the large, flat part of the
leaf
• Midrib-the large center vein
• Veins-the structural framework of
the leaf
• Margin-the edge of the leaf
Leaves-External
Leaves-Internal
• Upper and lower epidermis-skin of
the leaf that prevents the loss of
too much moisture
• Stomates-small openings under
the leaf for breathing or
transpiration
• Guard Cells-open and close
stomates
Leaves-Internal
• Chloroplasts-small green particles
that contain chlorophyll
– gives leaves their green color
– necessary for photosynthesis
Leaves-Internal
Leaves-Internal
Stems-External
• Lenticels-breathing pores
• Bud scale scars-show where
terminal buds have been located
• Leaf Scars-show where leaves
were attached
• Terminal bud-bud on the end of a
stem
• Axillary or lateral bud-bud on side
of stem
Stems-Internal
• Xylem-tissue that transports water
and nutrients up from the roots to
stems and leaves
• Phloem-tissue that transports food
down from leaves to roots
Stems-Internal
Phloem
Phloem
Xylem
Stems-Internal
• Cambium-thin, green, actively
growing tissue located between
bark and wood and produces all
new stem cells
• Bark-old inactive phloem
• Heartwood-old inactive xylem
• Sapwood-new active xylem
Stems-Internal
Bark
Cambium
Sapwood
Heartwood
Stems-Internal
• Monocota-plant stems have
vascular bundles that contain both
xylem and phloem in each bundle
– examples: corn, grasses
• Dicata-plant stems have the
phloem layer and xylem layer
separated by cambium
– example: trees
Stems-Internal
Monocot
Dicot
Roots-External
• Root cap-indicates growth of new
cells
• Root hairs-absorb moisture
(water) and minerals
Root
images
from a rice
plant
Roots-Internal
• Much like stems in that they have
a phloem, cambium, and xylem
layer
• Phloem-the outer layer that carries
food down the root
• Xylem-the inner layer that carries
water and minerals up to the stem
Layers of Roots
• Fibrous-many branched shallow
roots
– are easier to transplant
• Tap-long root with few branched
ones
– more difficult to transplant
Flowers
Flowers
• Sepals-Green parts that cover and
protect flower bud before it opens
• Petals-are really leaves that are
modified to attract insects for
flower pollination, the pretty part
that we call flowers
• Stamen-male part of the flower
• Pistil-female part of the flower
Flowers
Parts of the Stamen
• Filament-short stalk that
holds up the anther
• Anther-a sac-like structure
that contains pollen, the
male sex cells
Parts of the Pistil
• Ovules-the eggs or female sex
cells that become seeds if fertilized
• Ovary-if fertilized becomes a fruit
or seed coat
• Style-holds up the stigma and
connects it to the ovary
• Stigma-sticky part on top of style
where insects leave pollen
Parts of the Pistil
Stigma
Style
Ovary
Complete-vs-Incomplete
• Complete flowers have both male
and female parts
• Incomplete flowers have only male
or female parts
What are the
functions of these
plant parts?
Functions of Leaves
• Photosynthesis-manufactures food
in green plants which is the
beginning of the food chain for all
living things
• Photosynthesis is the process by
which carbon dioxide and water in
the presence of light are converted
to sugar and oxygen
Functions of Stems
• Translocation-moves water and
minerals from roots up to the
leaves and move food from the
leaves down to the roots
• Supports branches, leaves,
flowers, fruits and seeds
Functions of Roots
• Absorption-take water and
nutrients from the soil and conduct
them to the stem
• Anchor the plant and hold it
upright
• Store food for plant use
• Asexual reproduction in some
plants
Functions of Flowers
• Produce seeds used for sexual
reproduction
• Attract insects for pollination
(Pollination is the transfer of pollen
from anther to stigma.)
• Produce fruit to protect, nourish
and carry seeds