Plants

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Plants

• Classifying Plants
• 2 Main Groups of Plants
• A. Nonvascular have no vessels, no roots, no
  stems or leaves. Examples Mosses Liverworts

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• Bryophytes
• Depend on water for reproduction
• Lack vascular tissue (specialized tissues that
  conduct water and nutrients)
• Can only draw up water by osmosis
• Can only grow a few cm above ground

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Groups of Bryophytes

• Mosses
• Liverworts
• Hornworts

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Mosses

• Phylum Bryophyta
• Grow in areas w/ water

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Moss
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Liverworts

• Phylum Hepaticophyta
• Produce structures that look like tiny green
  umbrellas that produce egg sperm

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• B. Vascular have vessels to transport food and
  water. They have roots, stems and leaves.
  Example Grass, corn, trees, flowers, bushes
• Two Types of tissue
• 1. Xylem transports water2. Phloem transports
  food nutrients

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Two Groups of Vascular Plants

• A. Gymnosperms
• "naked seeds"
• cone bearing plants (seeds grow on cones)
• needle like leaves
• usually stay green year round
• wind pollinated
• Examples pine trees evergreens

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• B. Angiosperms
• flowering plants
• seeds are enclosed in a fruit
• most are pollinated by birds bees
• have finite growing seasons
• Examples grasses, tulips, oaks, dandelions
• Divided into two main groups Monocots Dicots

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Angiosperms
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Two Groups of Angiosperms

• A. Monocots
• Angiosperms have have 1 seed leaf (cotyledon)
• parallel veins on leaves
• 3 part symmetry for flowers
• fibrous roots
• Example lilies, onions, corn, grasses, wheat

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• A vascular bundle (scattered thru stem)B
  ground tissue storage, support

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• B. Dicots
• Angiosperms that have 2 seed leaves (cotyledons)
• net veins on leaves
• flowers have 4-5 parts
• taproots
• Examples trees and ornamental flowers

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• A epidermisB vascular bundle (arranged in a
  ring)C. ground tissue (pith)D. cortex

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Parts of the Plant

• A. Roots
• water and minerals are absorbed (taproots vs
  fibrous roots)
• also used to anchor the plant
• movement of water up to leaves is influenced by
  TRANSPIRATION
• Two types of roots
• Taproot-1 primary root long and thick while
  secondary roots are small
• Fibrous Root-no single root grows larger than the
  rest

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• B. Stems
• Support plant
• transport water through xylem
• transport nutrients through phloem
• a celery stalk soaked in food coloring will
  absorb the food coloring, you can see the xylem
• Two types of stems herbacious and woody

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• C. Leaves
• Photosynthetic organ of the plant, used to
  convert sunlight into food
• Structures
• Cuticle waxy covering, prevents water
  lossXylem vascular tissue, transports
  waterPhloem vascular tissue, transports
  nutrients (phood)Stomata (stoma) pores used for
  gas exchangeGuard cells open and close
  stomataMesophyll middle tissue, cells have
  chloroplasts used for photosynthesis, mesophyll
  consists of the spongy and palisade
  layersEpidermis layer of cells just under the
  cuticleVein a structure composed of xylem and
  phloem, veins run from the tips of the roots to
  the edges of leaves

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• D. Flower
• Reproductive organ of the plant
• Flowers are usually both male and female
• The male part of the flower is the STAMEN
• The female part of the flower is the PISTIL
• See your coloring sheet for more detail on flower
  anatomy

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Plant Reproduction

• Pollen is produced by the stamen.
• Pollen moves away from the plant via the wind or
  other pollinators (birds bees)
• The pollen lands on the pistil of another plant
  and fertilizes the eggs within the ovary
• The flower petals fall off, the ovary develops
  into a FRUIT that encloses the seeds
• Fruits are dispersed in a variety of ways (wind,
  animals)
• Fruits are not always edible, anything with a
  seed inside can be considered a fruit
  (helicopters, acorns, dandelions)

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Plant Reproduction

• Alternation of generations life cycle
• Diploid (2n) sporophyte stage
• Haploid (1n) gametophyte stage
• Produce multicellular embryo protected inside
  multicellular haploid (gametophyte egg sac) tissue

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Plant Reproduction

• Diploid (2n) sporophyte stage produces haploid
  spores by meiosis
• Haploid spores undergo mitosis to produce
  gametophyte stage
• Gametophyte makes gametes (eggs and sperm) by
  meiosis
• Zygote (2n) produces the new sporophyte

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Alternation of Generations
Gametophyte
2n Sporophyte
2n gametophyte
1n pollen
2n seed with plant embryo
Ovary with 1n ovules (eggs)
Sporophyte
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Asexual Reproduction in Plants

• Many plants can clone themselves, a process
  called VEGETATIVE PROPAGATION
• strawberry plants and other vine like plants send
  out runners, which grow into new plants
• some plant clippings will grow into new plants
• a Potato will grow into a new plant

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How Plants Grow

• Germination occurs when a seed sprouts (usually
  caused by changes of temperature and moisture)
• Monocots have 1 seed leaf (cotyledon), Dicots
  have 2 seed leaves

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• Perennials - live serval years, and reproduce
  many times, woody plants are perennials
• Annuals - a plant that completes its life cycle
  in one growing season (grows, flowers, reproduces
  and then dies)
• Biennials - takes two growing seasons to
  complete, it reproduces in the second growing
  season
• Plants grow only at their tips in regions called
  MERISTEMS
• PRIMARY GROWTH makes a plant taller at roots and
  stems
• SECONDARY GROWTH makes a plant wider, or adds
  woody tissue
• Tree Rings tell the age of a tree, each ring
  represents a growing season. The photo shows a
  tree who has been through four growing seasons.
  The lighter thinner rings are winter periods.
• VASCULAR CAMBIUM area of the tree that makes
  more xylem and phloem and forms the annual rings

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Plant Hormones

• Chemical substances that control a plants
  pattern of growth and development and the plants
  response to environmental conditions
• Auxins-simulate cell elongation
• Cytokinins-simulate cell division
• Gibberellins-increase in size
• Ethylene-causes fruits to ripen

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• Phototrophism-Response to light
• Gravitrophism-Response to gravity
• Thigmotropism-Response to touch

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