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Botany Basics


Botany Basics Crop Science 1 Fall 2004 September 14, 2004 Introduction Plants are essential to life on earth Primary food source for humans and other animals Provide ... – PowerPoint PPT presentation

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Title: Botany Basics

Botany Basics
  • Crop Science 1
  • Fall 2004
  • September 14, 2004

  • Plants are essential to life on earth
  • Primary food source for humans and other animals
  • Provide fuel, replenish the earth's oxygen
    supply, prevent soil erosion, slow down wind
    movement, cool the atmosphere, provide wildlife
    habitat, supply medicinal compounds, and beautify
    our surroundings

  • Many plants are familiar to us based on their
    external structures
  • Internal structures and functions often are
  • Understanding how plants grow and develop helps
    us capitalize on their usefulness

  • This course focuses on vascular plants
  • Contain water- and nutrient-conducting tissues
    called xylem and phloem
  • Ferns and seed-producing plants fall into this

  • Monocots
  • Monocotyledonous
  • Grasses and cereal grains
  • Produce only one seed leaf
  • Dicots
  • Dicotyledonous
  • Two seed leaves

Monocots vs Dicots
Plant Life Cycles
  • Based on its life cycle, a plant is classified as
  • Annual
  • Biennial
  • Perennial

  • Most common are weeds
  • Completes its life cycle in 1 year.
  • Go from seed to seed in 1 year or growing season.
  • During this period, they
  • grow, mature, bloom, produce seeds, and die.
  • Summer annuals - spring and summer
  • Winter annuals - fall and winter.

  • 2 years to complete its life cycle
  • First season, it produces vegetative structures
    (leaves) and food storage organs
  • The plant overwinters and then produces flowers,
    fruit, and seeds during its second season
  • Swiss chard, carrots, beets, and parsley

  • Live more than 2 years
  • Grouped into two categories
  • Herbaceous
  • Have soft, nonwoody stems that generally die back
    to the ground each winter
  • New stems grow from the plant's crown each spring
  • Woody
  • Trees and shrubs
  • Have woody stems that withstand cold winter

Internal Plant Parts
  • Cells
  • The basic structural and physiological units of
  • Most plant reactions occur at the cellular level
  • Tissues
  • Large, organized groups of similar cells that
    work together to perform a specific function
  • A unique feature of plant cells is that they are
    readily totipotent
  • Almost all plant cells retain all of the genetic
    information necessary to develop into a complete

  • Meristems are a plant's growing points
  • The site of rapid, almost continuous cell
  • These cells either continue to divide or begin to
    differentiate into other tissues and organs
  • You can manipulate meristems to make a plant do
    something you want, such as change its growth
    pattern, flower, alter its branching habit, or
    produce vegetative growth

Plant Organs
  • Plant Organs include external plant structures
    such as
  • Leaves
  • Stems
  • Roots
  • Flowers
  • Fruits and seeds
  • Each organ is an organized group of tissues that
    works together to perform a specific function

External Plant Parts
  • Plant Organs can be divided into two groups
  • Sexual reproductive parts
  • Produce seed
  • Include flower buds, flowers, fruit, and seeds
  • Vegetative parts
  • Include root, stems, shoot buds, and leaves
  • Are not directly involved in sexual reproduction
  • Often are used in asexual forms of reproduction
    such as cuttings, budding, or grafting

  • Root systems have a pronounced effect on
  • Plant size and vigor
  • Method of propagation
  • Adaptation to soil types
  • Response to cultural practices and irrigation
  • Originate from the lower portion of a plant or
  • They have a root cap, but lack nodes and never
    bear leaves or flowers directly

  • Principal functions are to
  • Absorb nutrients and moisture
  • Anchor the plant in the soil
  • Support the stem
  • Store food

Internal Root Structure
  • Internally, there are three major parts of a root
  • Meristem is at the tip and manufactures new
    cells it is an area of cell division and growth
  • Zone of elongation cells increase in size through
    food and water absorption. As they grow, they
    push the root through the soil
  • Zone of maturation is directly beneath the stem.
    Here, cells become specific tissues such as
    epidermis, cortex, or vascular tissue

Cross Section of a Root
  • Epidermis the outermost layer of cells
  • Responsible for absorbing water and minerals
    dissolved in water
  • Vascular tissue is located in the center of the
    root and conducts food and water
  • Cortex cells move water from the epidermis to the
    vascular tissue (xylem and phloem) and store food

External Root Structure
  • Externally, there are two major parts of a root
  • Root cap
  • The outermost tip
  • Consists of cells that are sloughed off as the
    root grows through the soil
  • Function is to protect the root meristem
  • Root hairs
  • Delicate, elongated epidermal cells that occur in
    a small zone just behind the root's growing tip
  • Function is to increase the root's surface area
    and absorptive capacity
  • Live 1 or 2 days
  • Transplants, tear off or dry out in the sun

Root Relationships
  • Many roots have a naturally occurring symbiotic
    (mutually beneficial) relationship with certain
  • Improve the plant's ability to absorb water and
  • Is called mycorrhizae (fungus root)

Types of Roots
  • Two major types of roots
  • Primary
  • Originates at the lower end of a seedling's
  • Lateral
  • Secondary root is a side or branch root that
    arises from another root

Primary Roots
  • Taproot
  • If the primary root continues to elongate
    downward, becomes the central feature of the root
    system, and has limited secondary branching
  • Hickory, pecan trees, and carrots

Lateral Roots
  • Fibrous root
  • Primary root ceases to elongate, and numerous
    lateral roots develop
  • Branch repeatedly to form the network of feeding
    roots found on most plants

How Roots Grow
  • During early development, a seedling absorbs
    nutrients and moisture from the soil around the
    sprouting seed. A band of fertilizer several
    inches to each side and slightly below newly
    planted seeds helps early growth of most row
  • As a plant becomes well established, the quantity
    and distribution of its roots strongly influence
    its ability to absorb moisture and nutrients. For
    most plants, the majority of the absorbing
    (feeder) roots are located in the top 12 inches
    of soil.
  • The soil environment in this region generally is
    best for root growth, with a good balance of
    fertility, moisture, and air spaces.

Factors Influencing Root Growth
  • Do not grow well water-saturated soil and die due
    to lack of oxygen (wet feet)
  • Penetrate deeper in loose, well-drained soil
  • A dense, compacted soil layer can restrict root
  • Roots grow laterally and often extend well beyond
    a plant's dripline
  • High salinity can restrict root growth
  • Roots dont seek out a healthy environment, but
    they thrive in one

Roots as Food
  • An enlarged root is the edible portion of several
    vegetable crops
  • Sweet potatoes are a swollen tuberous root
  • Carrots, parsnips and radishes are elongated