Plant Evolution Notes

Characteristics of All Plants:

• Eukaryotic: Cells contain a nucleus and complex organelles.
• Multicellular: Composed of multiple cells working together.
• Autotrophic: Capable of producing their own food through photosynthesis.
• Specialized Tissues & Organs: Possess distinct structures for specific functions.
• Nutrient Absorption: Able to absorb nutrients through roots.

Common Ancestry of Plants and Algae:

• Scientific evidence suggests plants and algae share a common ancestor.
• Algae require constant moisture, unlike plants.

Plant Evolution: Big Picture

• Evolutionary progression: Algae → Non-vascular plants → Vascular plants.
• Algae.
• Non-vascular plants: Evolved from algae (e.g., mosses).
• Vascular plants:
  • Seedless vascular plants (e.g., ferns).
  • Seed plants:
  • Gymnosperms (e.g., conifers).
  • Angiosperms (e.g., flowering plants).

First Plants to Evolve from Algae: Non-Vascular Plants

• First plants to evolve from algae were the first land plants.

Characteristics of Non-Vascular Plants:

• Examples: Mosses & Liverworts.
• Small size.
• Lack of true roots.
• Grow in damp, shady areas.

Rhizoids:

• Structures that anchor non-vascular plants.

Evolution of Vascular Tissues

• Plants evolved to have vascular tissues over time.

Benefits of Vascular Tissues:

• Plant plumbing system.
• Allows faster movement of materials.
• Provides structure.

Types of Vascular Tissues:

• Xylem:
  • Direction: Up.
  • Materials moved: Water.
• Phloem:
  • Direction: Down.
  • Materials moved: Sugar.

First Vascular Plants: Seedless Vascular Plants

Reproductive Structures:

• Utilize spores for reproduction (instead of seeds).

Examples of Seedless Vascular Plants:

• Ferns.
• Horsetails.
• Mosses (though mosses are primarily non-vascular, some have primitive vascular tissue).

Evolution of Seeds

• Allowed plants to fully move to dry ground.

Parts of a Seed:

• Embryo: The developing plant.
• Food Store: Provides nutrients for the embryo.
• Seed Coat: Protective outer covering.

Seed Dispersal:

• Methods:
  • Wind.
  • Water.
  • Animals.

Benefits of Seed Dispersal:

• Limits competition between parents & offspring.

Gymnosperms

Meaning of "Gymnosperm":

• First seeded vascular plants.
• "Naked Seeds".

Seed Carriage:

• Gymnosperms carry seeds in cones.

Examples of Gymnosperms:

• Conifers.
• Ginkgos.
• Cycads.

Angiosperms

Characteristics of Angiosperms:

• Are flowering plants.
• Seeds are NOT naked.
• Comprise more than 75% of the plant kingdom.

Success of Angiosperms:

• The evolution of flowers has made angiosperms highly successful.
• Attract pollinators.
• Ovary becomes fruit.

Flowers

Female Portion of a Flower (Pistil):

• Stigma + Style + Ovary = Pistil

Male Portion of a Flower (Stamen):

• Filament + Anther = Stamen

Parts of a Flower:

• Stigma.
• Style.
• Ovary.
• Anther.
• Filament.
• Receptacle.

Plant Structures

Functions of Plant Structures:

• Leaves: Make food through photosynthesis.
• Flowers: Contain reproductive parts & seeds.
• Stem: Carries food & water around.
• Roots: Absorbs water.

Major Plant Cell Structures:

• Cell Wall.
• Chloroplast.
• Peroxisome.
• Ribosomes.

Plant Type Table:

Gymnosperms vs. Angiosperms: Venn Diagram

Gymnosperms:

• Seeds are exposed.
• Reproduce using cones.
• Usually evergreen trees.

Shared Characteristics:

• Have vascular tissue.
• Reproduce using seeds.

Angiosperms:

• Seeds are enclosed in fruit.