Plant Physiology

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Plant Physiology

• Essential Standard 3.00 Summarize Plant Anatomy

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Objective 3.01

• Discuss biological terms used to describe plants.

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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

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Plant Sciences

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

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Agronomy

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

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Forestry

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

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Horticulture

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

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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

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Leaf Retention

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

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Plant Hormones

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

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Inhibitors

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

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Cytokinins

• Hormones that work with auxins to stimulate cell
  division.

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Gibberellias

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

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Auxins

• Hormones that speed plant growth by stimulating
  cell enlargement

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Moisture in Plants

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

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Plant Growth

• Dormant
• A plant rest or grows very little
• Response to an adverse condition

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Season Crop Type

• Cool Season
• Plants relish cool weather
• Pansies grow best in spring or fall
• Warm Season
• Grow best in summer and early fall
• Zinnia
• Marigold
• Vinca
• Poinsettia

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Objective 3.02

• Discuss the anatomy and functions of plants.

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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

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Leaves-Internal

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

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Leaves-Internal
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Leaves-Internal
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Leave-Functions

• Photosynthesis
• process by which plants capture sunlight and use
  it to convert carbon dioxide and water into food
• Respiration
• converts sugars and starches into energy
• Transpiration
• release of water vapor from the leaves of plants
• It also cools the plant

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Leave-Additions

• Sessile describes leaves without a petiole
• Example zinnia
• Bracts are modified leaves
• Example poinsettia
• Needles and scales are modified leaves
• Example pine tree

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Leave-Additions

• Glabrous leaves or stems have a smooth non-hairy
  feel
• Example southern magnolia
• Pubescent leaves or stems have a hairy feel
• Example African violet

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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

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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

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Stems-Internal
Monocot
Dicot
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Roots-External

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

Root images from a rice plant
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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

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Layers of Roots

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

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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

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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

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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

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What are the functions of these plant parts?
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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

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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

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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

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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

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Objective 3.03

• Discuss floriculture and landscape plants

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Taxonomy

• The science of classifying and identifying plants
• Scientific names are used because the same common
  name is used for different plants in different
  areas of the world.

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Karl von Linne

• Swedish botanist that developed the binomial
  system of naming plants using two Latin words to
  indicate the genus and species.
• Linne changed his name to the Latin name Carolus
  Linneaus.

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Scientific Names

• Latin is the language used for scientific
  classification.
• The first word is the genus and the second word
  is the species. If there are additional words,
  they indicate a variety or cultivar.

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Genus vs. Species

• Plants in the same genus have similar
  characteristics.
• Plants in the same species consistently produce
  plants of the same type.

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Scientific Classification

• The broadest category of scientific
  classification is the Kingdom--either plant or
  animal.
• The broadest category in the plant kingdom is
  division or phylum.

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Divisions

• The four most important divisions of the plant
  kingdom are
• Thallophites
• Bryophytes
• Pteriophytes
• Spermatophytes

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Spermatophytes

• Contains flowering or seed-bearing plants
• Two subdivisions are
• Gymnosperms and Angiosperms

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Common Plant Genus

• Pinus-Pine
• Acer-Maple
• Ilex-Holly
• Ficus-fig

• Cornus-dogwood
• Rhododendron-rhododendron
• Quercus-oak