Wednesday, July 4, 2012

Kingdom Plantae

Kingdom Plantae contains nearly 300,000 different kinds of plants. They also place the macroscopic, multicellular brown algae (Division Phaeophyta) and red algae (Division Rhodophyta) in the Kingdom Plantae.Although this does not make it the largest kingdom, many might argue that it is the most important one.In the process known as "photosynthesis ", plants use the energy of the Sun to make food and oxygen. This complex chemical reaction provides nearly all the oxygen in Earth's atmosphere and all the food required by living things. Although some protists and bacteria are capable of performing photosynthesis, plants do most of the photosynthesis on Earth.
                 The ancestors of plants first appeared in the seas nearly 700 million years ago. Another 265 million years passed before the first plants appeared on land. These early land plants looked very different than the plants you're familiar with today. In fact, many of them didn't even have roots, stems, or leaves! Since then, plants have taken on a variety of forms and are found in most places on Earth.
General Characteristics
A. Contain chlorophylls a and b.
B. Cell walls made of cellulose.
C. Have tissues and organs (roots, stems and leaves).
 Evolution of Plants
A. Evidence that plants evolved from algae
1. Green algae and plants both have chloroplast with chlorophylls a and b
2. Both have cell walls made of cellulose.
3. Both form starch as stored glucose.
4. Both demonstrate alternation of generations

Problems with life on land
A. Dehydration
1. Adaptations
a) Roots, vascular tissue, cuticles and bark
B. Support
1. Adaptations
a) Stiffer, thick cell walls; wood
C. Distribution of gametes and/or spores
1. Adaptations
a) Water tight seeds and/or spores.
b) Spores lighter than air.

Classification of Plants

A. Phylum Bryophyta 
  • Primitive
  • Lack vascular tissue
  • Lack true roots
  • Mosses and liverworts (Hepatophyta)
B. Super Phylum Tracheophyta
  • More advanced than Bryophytes
  • Contain vascular tissue
C. Phylum Pterophyta 
  • Reproduce by spores
  • Leaves generally grow from underground stems
  • Ferns and horse tails
D. Phylum Coniferophyta
  • Produce naked seeds in cones
  • Many are evergreens
  • Produce soft wood
  • Needle like leaves
  • Redwoods, pines, cypress and junipers
E. Phylum Anthophyta
  • Flowering plants
  • Either herbaceous or hardwoods
  • Most advanced of all plant forms
a) Class Monocotyldonae (Monocots)
  • Seeds contain one cotyledon
  • Leaves have parallel veins
  • Flower parts are usually in multiples of 3
  • Lack cambium
  • In the stem, vascular bundles are scattered
  • Generally wind pollinated
  • All are herbaceous with a few exceptions
b) Class Dicotyledonae (Dicots)
  • This class is now called Eudicotyledonae
  • Seeds contain two cotyledons
  • Leaves have netted veins
  • Flower parts are usually in multiples of 4 or 5
  • Have cambium
  • Vascular bundles are arranged in a cylinder, in the stem.
  • Generally pollinated by animals.