Angiosperms

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CHAPTER 26

• Angiosperms

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What is an Angiosperm?

• Plant that produces flowers, and develops seeds
  enclosed in a fruit
• Division Anthophyta
• Two classes
• Monocotyledons 60,000 species
• Dicotyledons 170,000 species

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Angiosperm Adaptations

• Most successful plants on Earth
• Adaptations allow them to survive in almost any
  habitat
• Roots and stems adapted for storing food
• Bulb short stem enclosed in fleshy leaf bases
• Corm short, thickened underground stem not
  enclosed in leaf scales
• Tuber swollen root or stem with buds that will
  sprout new plants
• Leaves respond to amount of sunlight and moisture
  available
• Different shapes and sizes

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Angiosperm Lifespans

• Life span reflects the plants strategy for
  surviving
• Life spans
• Annual live for year or less
• Biennials lasts two years
• Perennials lives for several years, produces
  flowers and seeds periodically (usually once a
  year)

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Angiosperm Structure

• Root
• Stem
• Leaves

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Roots

• Underground parts of plant
• Functions
• Anchor plant in ground
• Absorb water and minerals
• Transport materials to base of stem

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Root Structure

• Figure 26.10, p. 640
• Epidermis outermost cell layer
• Root hair extension of a single epidermal cell
• Cortex functions to transport water
• Parenchyma tissue that makes up cortex, storage
• Endodermis single layer of cells, waterproof
  seal
• Pericycle tissue that gives rise to lateral
  roots
• Cambium tissue to make more xylem and phloem
  cells
• Apical meristem growth tissue just behind the
  root tip, cells are capable of mitosis
• Root cap tough, protective layer of living
  parenchyma cells that covers the tip of each root

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Stems

• Aboveground parts of plants that support leaves
  and flowers
• Different forms
• Functions
• Support
• transport

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Structure of Stems

• Vascular Tissue
• Sink uses or stores excess sugars made during
  photosynthesis
• Vessel cell elongated cell with open ends
• Fibers elongated, elastic cells that contain
  lignin, makes cell walls rigid
• Sieve cells make up phloem, thin-walled cells
  with plates on their end walls, no nuclei
• Companion cell paired with sieve cell, has
  nucleus, controls movement thru sieve cell
• Lateral meristem located at nodes along stem,
  gives rise to new branches

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Leaves

• Primary function trap light energy for
  photosynthesis
• Leaf Blade flat, broad green structure
• Petiole stalk that joins leaf blade to stem
• Transpiration process of evaporating water from
  stomata (openings in leaf epidermis)
• Guard cells surround and control the size of the
  opening in a stomata
• Mesophyll photosynthetic tissue of leaf

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Internal Anatomy of a Leaf

• Cuticle covers leafs upper epidermis
• Palisade mesophyll where most photosynthesis
  occurs
• Spongy mesophyll underside of leaf, less
  chloroplasts, allows gases to move between
  palisade cells and out of leaf
• Vascular tissue within spongy mesophyll
• Lower epidermis many stomata