18.07 Kingdom Plantae

Overview

• The kingdom Plantae consists of multicellular, photosynthetic organisms.
• Plants have specialized structures above and below ground, often forming complex, branched bodies.
• Examples range from ferns and mosses to ancient trees like bristlecone pines.

Characteristic Features of Plants

1. Eukaryotic and Multicellular:

• Cells are specialized and organized into tissues and organs.

1. Photosynthesis:

• Chloroplasts in some cells enable autotrophic nutrition by converting sunlight, CO₂, and water into energy.

1. Autotrophic Nutrition:

• Plants produce their own food via photosynthesis.

1. Cell Structure:

• Cell Walls:
  • Composed of cellulose, providing structural support.
• Vacuoles:
  • Large, often permanent, vacuoles help maintain turgidity for support and storage.
• Flagella:
  • Rare; seen in male gametes of ferns and other primitive plants.

1. Specialized Cells:

• Limited types of cells, differentiated to perform specific functions (e.g., photosynthetic cells, root cells).

1. Reproduction:

• Asexual (e.g., spores) and sexual reproduction (e.g., seeds, pollen).

Ecological Role

• Primary Producers:
  • Form the base of most ecosystems by providing energy and oxygen through photosynthesis.
• Carbon Cycling:
  • Absorb CO₂, contributing to the global carbon cycle.

Examples

• Tree Ferns (Cyathea sp.):
  • Found in temperate rainforests (e.g., Whirinaki Conservation Park, New Zealand).
• Bristlecone Pines:
  • Ancient trees in high altitudes (e.g., Ashdown Gorge Wilderness, Utah).
  • Estimated age: 2,000–3,000 years.

Key Term

• Plantae: A kingdom of multicellular, eukaryotic organisms with cellulose-based cell walls, capable of photosynthesis, and showing autotrophic nutrition.

Visual Representation

• Figure A: Tree ferns (Cyathea sp.) thriving in New Zealand’s Whirinaki Conservation Park.

• Figure B: Bristlecone pines, some of the oldest known trees, growing at high altitudes in Utah.

Summary

• Plantae includes all multicellular photosynthetic organisms.
• Characterized by:
  • Eukaryotic structure with specialized tissues.
  • Autotrophic nutrition via photosynthesis.
  • Cell walls of cellulose and large vacuoles for support.
• They play a vital role in ecosystems as oxygen producers and as the primary source of energy in most food chains.