1.3 The Plant Kingdom

Algae

• Characteristics: Simple, thalloid, autotrophic, and largely aquatic.
• Classification:
  • Chlorophyceae (Green Algae): Starch storage, cellulose cell wall.
  • Phaeophyceae (Brown Algae): Laminarin/mannitol storage, algin in cell wall.
  • Rhodophyceae (Red Algae): Floridean starch storage, no flagella.
• Economic Importance: Food source, agar, algin, diatomaceous earth.

Bryophytes

• Characteristics: "Amphibians of the plant kingdom," non-vascular, dominant gametophyte.
• Liverworts vs. Mosses:
  • Liverworts: Thalloid or leafy, unicellular rhizoids.
  • Mosses: Leafy, multicellular rhizoids, protonema stage.
• Economic Importance: Pioneer species, prevent soil erosion, source of peat.

Pteridophytes

• Characteristics: First terrestrial plants with vascular tissue, dominant sporophyte.
• Homospory vs. Heterospory:
  • Homospory: One type of spore.
  • Heterospory: Two types of spores (microspores and megaspores).
• Economic Importance: Ornamental plants, soil binders, medicinal uses, biofertilizers.

Gymnosperms

• Characteristics: "Naked seeds," mostly evergreen trees or shrubs.
• Life Cycle of Pinus: Wind pollination, no water needed for fertilization, seed contains embryo and endosperm.
• Economic Importance: Timber, resins, edible seeds, medicinal uses.

Angiosperms

• Characteristics: Flowering plants, seeds enclosed in a fruit.
• Double Fertilization: One male gamete fuses with the egg (zygote), the other fuses with polar nuclei (endosperm).
• Economic Importance: Food, fodder, fuel, fiber, medicines.

Monocots vs. Dicots