Focus on Kingdom Plantae and their evolution from green algae.
Early plants transitioned from water to land, facing challenges:
Strategy development to avoid drying out (desiccation).
Need for structural support.
Capturing sunlight for photosynthesis.
Effective dispersal of reproductive cells.
Seed plants have adapted to arid habitats while seedless plants typically thrive in moist environments.
Evolution of plants involved adapting to land.
Importance of structural modifications that accompany this transition.
Streptophytes: Includes Charophytes (green algae) and Embryophytes (land plants).
Distinction between vascular and nonvascular plants:
Nonvascular: Bryophytes (liverworts, hornworts, mosses).
Vascular: Seedless plants (lycophytes, pterophytes, ferns, etc.).
Further classification of land plants includes seed plants (
Spermatophytes).
Plants show two dominant stages:
Haplontic: Dominant haploid stage (gametophyte).
Diplontic: Dominant diploid stage (sporophyte).
In primitive plants, the gametophyte is predominant.
As plants evolved, sporophyte generation became more dominant, with gametophyte getting smaller.
Key life cycle terms:
Gametophyte: haploid generation producing gametes.
Sporophyte: diploid generation producing spores.
Location of growth in roots and shoots.
Apical meristems produce new cells, enabling growth and elongation.
Protects root tips through the root cap as they penetrate soil.
Transition to land involved significant adaptations:
Nonvascular Plants: Initially limited to few inches in height.
Vascular Tissue: Evolved to transport water (xylem) and photosynthetic products (phloem), allowing for greater height and capability to grow away from moisture sources.
Other adaptations:
Waxy cuticle helps prevent desiccation but also limits CO2 intake.
Stomata for gas exchange, protective flavonoids against UVB damage.
Development of secondary metabolites (e.g., alkaloids for defense).
Vascular plants developed true roots, which enhance anchoring and nutrient absorption.
Mycorrhizal relationships improve nutrient uptake.
Development of leaves (microphylls and megaphylls) increased photosynthesis efficiency.
Dominant sporophyte phase, dependent on water for reproduction.
Major types include:
Lycophytes: Club mosses, spike mosses, quillworts.
Monilophytes: Horsetails, whisk ferns, ferns.
Club mosses have microphylls; horsetails have silica in their tissue.
Ferns are the most recognized group, thriving in moist environments with large compound leaves (fronds).
Fern life cycles feature alternation of generations with clear dominant sporophyte phases.
Mosses: Key role in tundra ecosystems.
Ferns: Aid soil development, prevent erosion, help nutrient cycling, and may harbor nitrogen-fixing cyanobacteria.
Use of peat moss in fuel and horticulture exemplifies their human utility and ecological function.
Mycorrhizal Symbiosis: Close relationship between land plants and fungi aids nutrient acquisition.
Nitrogen Fixation: Essential for plant growth, facilitated only by bacteria, underlining interconnectedness of soil flora.
Seedless Plants
Focus on Kingdom Plantae and their evolution from green algae.
Early plants transitioned from water to land, facing challenges:
Strategy development to avoid drying out (desiccation).
Need for structural support.
Capturing sunlight for photosynthesis.
Effective dispersal of reproductive cells.
Seed plants have adapted to arid habitats while seedless plants typically thrive in moist environments.
Evolution of plants involved adapting to land.
Importance of structural modifications that accompany this transition.
Streptophytes: Includes Charophytes (green algae) and Embryophytes (land plants).
Distinction between vascular and nonvascular plants:
Nonvascular: Bryophytes (liverworts, hornworts, mosses).
Vascular: Seedless plants (lycophytes, pterophytes, ferns, etc.).
Further classification of land plants includes seed plants (
Spermatophytes).
Plants show two dominant stages:
Haplontic: Dominant haploid stage (gametophyte).
Diplontic: Dominant diploid stage (sporophyte).
In primitive plants, the gametophyte is predominant.
As plants evolved, sporophyte generation became more dominant, with gametophyte getting smaller.
Key life cycle terms:
Gametophyte: haploid generation producing gametes.
Sporophyte: diploid generation producing spores.
Location of growth in roots and shoots.
Apical meristems produce new cells, enabling growth and elongation.
Protects root tips through the root cap as they penetrate soil.
Transition to land involved significant adaptations:
Nonvascular Plants: Initially limited to few inches in height.
Vascular Tissue: Evolved to transport water (xylem) and photosynthetic products (phloem), allowing for greater height and capability to grow away from moisture sources.
Other adaptations:
Waxy cuticle helps prevent desiccation but also limits CO2 intake.
Stomata for gas exchange, protective flavonoids against UVB damage.
Development of secondary metabolites (e.g., alkaloids for defense).
Vascular plants developed true roots, which enhance anchoring and nutrient absorption.
Mycorrhizal relationships improve nutrient uptake.
Development of leaves (microphylls and megaphylls) increased photosynthesis efficiency.
Dominant sporophyte phase, dependent on water for reproduction.
Major types include:
Lycophytes: Club mosses, spike mosses, quillworts.
Monilophytes: Horsetails, whisk ferns, ferns.
Club mosses have microphylls; horsetails have silica in their tissue.
Ferns are the most recognized group, thriving in moist environments with large compound leaves (fronds).
Fern life cycles feature alternation of generations with clear dominant sporophyte phases.
Mosses: Key role in tundra ecosystems.
Ferns: Aid soil development, prevent erosion, help nutrient cycling, and may harbor nitrogen-fixing cyanobacteria.
Use of peat moss in fuel and horticulture exemplifies their human utility and ecological function.
Mycorrhizal Symbiosis: Close relationship between land plants and fungi aids nutrient acquisition.
Nitrogen Fixation: Essential for plant growth, facilitated only by bacteria, underlining interconnectedness of soil flora.