Section 1A Concise

Introduction to Land Plants

• Importance of plants: Oxygen, food, medicines, textiles (cotton, linen), wood, aesthetic value, photography.

Plant Cell Structure

• Kingdom: Plantae; Multicellular eukaryotes.

• Key organelles: Central vacuole, chloroplast, cell wall, plasma membrane, mitochondrion.

• Central vacuole: Storage, waste breakdown, hydrolysis.

Plant Evolution

• Land plants evolved from green algae (charophytes).

• Key traits shared: multicellularity, photosynthetic pigments, cellulose cell walls.

Plant Diversity

• Land plants: 325,000 species adapted to various environments.

• Nonvascular plants (bryophytes) vs. vascular plants.

Life Cycle of Plants

• Plants exhibit alternation of generations: gametophyte (haploid) and sporophyte (diploid) stages.

• Specific traits: walled spores, apical meristems.

Bryophytes

• Dominated by gametophytes; small herbaceous plants: liverworts, mosses, hornworts.

• Sporophyte dependent on gametophyte.

Seedless Vascular Plants

• Key innovations: vascular tissue (xylem and phloem), roots, leaves, sporophylls.

• Two groups: Lycophytes (club mosses) and Monilophytes (ferns).

Seed Plants

• Divided into gymnosperms (naked seeds) and angiosperms (seeds in fruits).

• Gymnosperms: conifers; Angiosperms: flowering plants (~90% of species).

Summary of Plant Evolution

• Origins date back 470 million years; fossil evidence supports this.

• Adaptations led to diversification among plant groups in terrestrial environments.