Plant Parts and their Functions

1
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

2
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

3
Plant Sciences

• Applied plant sciences are based on the purposes
  for which the plants are grown
• Agronomy
• Forestry
• Horticulture

4
Agronomy

• The science and practice of growing field crops
  such as cotton, wheat, tobacco, corn and soybeans.

5
Forestry

• The science and practice of growing, managing and
  harvesting trees for building materials and other
  products.

6
Horticulture

• The science and practice of growing, processing
  and marketing fruits, vegetables, and ornamental
  plants

7
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

8
Leaf Retention

• Deciduous-loses leaves during the dormant season
• Evergreen-keeps leaves and remains green
  year-round

9
Plant Hormones

• Several types of hormones are used to help plants
  work more efficiently.
• Inhibitors
• cytokinins
• gibberellias
• auxins

10
Inhibitors

• Inhibitors hasten fruit ripening, retain seed
  germination and stem elongation.

11
Cytokinins

• Hormones that work with auxins to stimulate cell
  division.

12
Gibberellias

• Hormones that stimulate cell elongation,
  premature flowering, and breaking of dormancy.

13
Auxins

• Hormones that speed plant growth by stimulating
  cell enlargement

14
Moisture in Plants

• Turgid-plant is swollen or filled with moisture
• Wilted-plant is limp because it does not have
  enough moisture

15
Plant Parts

• Leaves
• Stems
• Roots
• Flowers

16
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

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Leaves-External
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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

19
Leaves-Internal

• Chloroplasts-small green particles that contain
  chlorophyll
• gives leaves their green color
• necessary for photosynthesis

20
Leaves-Internal
21
Leaves-Internal
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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

23
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

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Stems-Internal
Phloem
Phloem
Xylem
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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

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Stems-Internal
Bark
Cambium
Sapwood
Heartwood
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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

28
Stems-Internal
Monocot
Dicot
29
Roots-External

• Root cap-indicates growth of new cells
• Root hairs-absorb moisture (water) and minerals

Root images from a rice plant
30
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

31
Layers of Roots

• Fibrous-many branched shallow roots
• are easier to transplant
• Tap-long root with few branched ones
• more difficult to transplant

32
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

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Flowers
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Parts of the Stamen

• Filament-short stalk that holds up the anther
• Anther-a sac-like structure that contains pollen,
  the male sex cells

35
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

36
Parts of the Pistil
Stigma
Style
Ovary
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Complete-vs-Incomplete

• Complete flowers have both male and female parts
• Incomplete flowers have only male or female parts

38
What are the functions of these plant parts?
39
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

40
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

41
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

42
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