general biology

• Plants are living things that have roots, stems, and leaves ~ some have flowers
• Plants are made of cells that have cell walls, a large central vacuole, and chloroplasts
• • Chloroplasts contain a green pigment called chlorophyll that play a role in photosynthesis
• ORIGIN OF EVOLUTION - there are between 260,000 and 300,000 plant species identified to date
• Oldest fossil plants are about 420 million years old – descendants of algae (aquatic)
• Cone-bearing plants, such as pines, probably evolved from a group of plants that grew 350 million years ago

  • Flowering plants did not exist until about 120 million years ago
• Protections and Support - Leaf
• VASCULAR: have tube-like structures that carry water, nutrients, and other substances through the plant
• • NONVASCULAR: do not have these tube-like structures and use other ways to move water and substances
• • Binomial Nomenclature: two word system of naming things.
• Seedless Nonvascular Plants- Don’t grow from seeds; just a few cells thick and only 2 to 5 cm in height; no flowers or cones ~ reproduce by spores

  • ex. Mosses, Liverworts, and Hornworts
• Seedless Vascular Plants

  • Reproduce by spores
  • Have long, tube-like cells that carry water, minerals, and food to cells throughout the plant
  • Can grow bigger and thicker because of this
  • 1,000 species of fern, ground pine, and spike mosses; 12,000 species of ferns! examples: fern, ground pine, spike mosses, and horsetail
• • Fern - Largest group of seedless vascular plants
• • Fern leaves are called fronds​
• • Ferns produce spores in structures on underside of fronds
• • Ferns that lived 360 million years ago grew as tall as 25 m, but today, tallest tree ferns are about 3 m to 5 m in height
• Club mosses

  • Ground pines and spike mosses
  • Have needle-like leaves
  • Spores produced at end of stem in structures that look like tiny pine cones
  • Endangered in some areas, as they have been collected to make wreaths
• HORSE TAIL

  • - Stem is jointed and has a hollow center surrounded by a ring of vascular tissue; at each joint leaves grow out from around the stem
  • Spores are produced in a cone-like structure at the tips of some stems
  • Stems contain silica, a gritty substance found in sand – “scouring rush”
• • When ancient seedless plants died, they became submerged in water and mud before they decomposed – over time, plant material became coal!
• • Today, decaying plants are compressed into a substance called peat, which forms from the remains of sphagnum moss – used as low-cost fuel in places such as Ireland and Russia
• Uses of Seedless Vascular plants

  • Peat and sphagnum mosses used for gardening
  • Peat used as soil conditioner
  • Ferns used for weaving material and basketry
  • Rhizomes and young fronds of ferns are edible
  • Dried stems of one type of horsetail can be ground into flour
  • Folk medicines to treat bee stings, burns, fevers, and even dandruff!
• Seed Plants

  • Have leaves, roots, stems, and vascular tissue; produce seeds
  • Gymnosperms and Angiosperms
  • Leaf made up of different layers of cells
  • Waxy cuticle
  • Epidermis (Stomata surrounded by guard cells)
  • Palisade layer – most food produced here
  • Spongy layer – veins containing vascular tissue found here
  • Lower Epidermis
• Leaf Structure

  
• • Herbaceous stems: soft and green
  • Woody stems: hard, rigid