Plants

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Plants

• Chapter 6
• pp 113-131

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Characteristics of Plants

• Plants have chloroplasts which contain
  chlorophyll
• Chlorophyll green chemical that traps light
  energy
• Make their own food using photosynthesis
• Rigid cell wall surrounds each cell

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Plant Classification

• Divided into vascular and nonvascular plants
• Vascular tissue long tube-like cells that
  transport water and nutrients
• Division replaces phylum

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Origin of Plants

• Thought to have evolved from plant-like protists
• Both contain the same type of chlorophyll .
• Plants decay quickly so there are very few fossils

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Earliest Land Plant

• Rhynia major
• Fossils about 420 m.y.o.
• No leaves
• Stem grew underground

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Life on Land

• Advantages
• More direct sunlight for photosynthesis
• More carbon dioxide
• Disadvantages
• Still need water to carry nutrients in and waste
  out
• Need to support weight

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Nonvascular Plants

• Grow close to the ground in moist areas
• No roots, absorb water by osmosis through
  hair-like cells
• Water carries minerals from soil

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Nonvascular Plants

• Only one division Bryophyta
• Simple, rootless plants that are usually only a
  few cells thick
• Commonly called mosses and liverworts

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• Typically grow in mats of fine, soft, upright
  stems
• Leaves grow from all sides of the stems and vary
  in shape
• Species are identified by leaves

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Moss Life Cycle

• Alternation of Generations - continual cycle
  which alternates between the spore-producing
  phase and the sex-cell producing stage

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Vascular Plants

• Contain 2 types of vascular tissue
• Xylem carry water and dissolved minerals from
  roots to leaves
• Phloem carry food from leaves to all parts of
  the plant

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Vascular Plant Organs

• Roots anchor plant into soil, take in water and
  nutrients
• Stems support the plant, transport water and
  nutrients
• Leaves collect light energy to make food

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Ferns

• Vascular plant that reproduces with spores
• Underground stems with leaves divided into many
  leaflets
• Over 800 species

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Seed Plants

• Seed reproductive part of a plant that contains
  an embryo and a food supply
• Two divisions of seed plants
• Gymnosperms naked seed
• Angiosperms flowering plants

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Gymnosperms

• Produce seeds in cones
• Generally keep leaves year round
• Commonly called conifers

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Seed Production

• Pollen produced in male cones
• Female cones contain egg cells
• Cone becomes dry and scales open to release seeds

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Angiosperms

• Produce seeds inside a flower
• Divided into two classes based on the number of
  leaves found on the embryo
• Monocot and Dicot

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