Chapter 31-Plants and the Conquest of Land

Page 1: Early Algae and Plant Ancestors

• Streptophyte Algal Diversity:

  • Originated around 600 million years ago (mya).

• Biological Soil Crust:

  • Forms on rock surfaces, signifies early interactions between algae and substrate.

• Earliest Land Plants:

  • Hypothetical earliest land plants evolved around 590 mya, interacting with beneficial microbiota.

  • Last common ancestor of land plants appears around 510 mya, contributing to the lineage of Bryophyta (mosses, liverworts, etc.).

Page 2: Key Concepts and Themes

• Ancestry of Modern Plants:

  • Discusses how modern plants evolved from aquatic ancestors.

• Impact of Land Plants on the Earth:

  • Land plants dramatically changed terrestrial and atmospheric conditions.

Page 3: Diploid-Dominant Life Cycle

• Life Cycle Process:

  • Diploid cells undergo meiosis to create haploid gametes.

  • Gametes fuse to form a new diploid zygote.

Page 4: Haploid-Dominant Life Cycle

• Zygotic Life Cycle Description:

  • Haploid cells produce gametes via mitosis.

  • Gametes fuse to form a diploid zygote that undergoes meiosis to form haploid individuals.

Page 5: Sporic Life Cycle – Alternating Generations

• Sporophyte and Gametophyte:

  • Diploid sporophyte produces haploid spores by meiosis.

  • Spores develop into gametophytes, which produce gametes via mitosis that fuse to form a new sporophyte.

Page 6: Ancestry and Diversity of Modern Plants

• Kingdom Plantae:

  • multicellular, eukaryotic organisms with plastids.

    • Contains DNA material in the nucleus

  • Primarily terrestrial and evolved from aquatic green algal ancestors.

• Adaptations to Terrestrial Life:

  • Structural modifications that allow survival and reproduction on land.

Page 7: Clades of Plants (very important)

• Non-vascular plants (Bryophytes): Include mosses, liverworts, and hornworts, which lack specialized tissues for water transport.

• Vascular plants: Characterized by the presence of vascular tissues (xylem and phloem) that facilitate the transport of water and nutrients.

• Seedless vascular plants: Such as ferns and horsetails, which reproduce via spores.

• Seed plants: Further divided into gymnosperms and angiosperms, which reproduce through seeds and flowers, respectively.

• Non-vascular plants (Bryophytes): Mosses and liverworts, which require moist environments for reproduction.

• Vascular plants: Include seedless plants like ferns, as well as seed plants, which are further divided into gymnosperms and angiosperms.

• Streptophytes:

  • Includes all plants and some algae (excludes chlorophytes the green algae).

• Embyrophytes:

  • Encompasses all land plants (vascular and non-vascular).

• Tracheophytes:

  • Includes only vascular plants, both seed and non-seed.

• Spermatophytes:

  • Clade that includes seed-producing plants (fruited or fruitless).

Page 8: Ancestry of Streptophyte Plantae

• Originated from a photosynthetic protist ancestor classified in streptophyte algae.

• Share several derived traits with land plants:

  • Unique cytokinesis.

  • Plasmodesmata for cellular communication.

  • Sexual reproduction using distinct egg and sperm.

Page 9: Distinctive Features of Land Plants

• Developed several adaptations to thrive in terrestrial environments:

  • Multicellular, three-dimensional body structures for stability.

  • Structural adaptations to minimize water loss.

  • Emergence of specialized tissues from apical meristems at growth tips.

Page 10: Distinctive Reproductive Features

• Survival Traits: (Helps plants survive in terrestrial habitats)

  • Alternation of generations: two multicellular stages (sporophyte and gametophyte).

  • Sporophyte nourishes embryos, enhancing survival.

  • Production of tough, resistant spores allows wide dispersal.

Page 11: Plant Phyla Overview

• Non-Vascular Plants:(Bryophytes)

  • Liverworts: Hepatophyta.

  • Mosses: Bryophyta.

  • Hornworts: Anthocerophyta.

• Vascular Plants:

  • Lycophytes, Pteridophytes, Cycads, Ginkgos, Conifers, Angiosperms.

Page 12: Bryophytes

• Clade of non-vascular plants, including liverworts, hornworts, and mosses.

• Typical characteristics:

  • Grows tall, reliant on moist habitats.

  • Reproductive traits include alternation of generations and multicellular embryos.

• Monophyletic phylum: They all have a common ancestor

  • Nonvascular, Moist Habitats → water for reproduction

Page 13: Bryophyte Traits

• Common Traits:

  • Nonvascular, thrive in moist habitats, require water for reproduction, utilize photosynthesis.

Page 14: Liverworts and Hornworts

• Liverworts:

  • Characteristic gametophyte structures and sporophytes.

Page 15: Mosses

• Characterized by mat structures (e.g., peat).

• Possess primitive conducting systems.

Page 16: Sporic Life Cycle

• Two Generations:

  • Sporophyte: diploid, produces spores.

  • Gametophyte: haploid, produces gametes.

  • Streptophyte: Zygotic life cycle

  • Bryophytes: Sporic - but exhibit a haploid-dominant life cycle.

Page 17: Gametophyte Dominance

• Gametophyte is dominant; sporophyte is small, attached, and dependent on gametophyte.

Page 18: Matrotrophy

• Definition:

  • Maternal nutrition of the embryo, providing protection and nutrients.

  • Characteristic of all land plants.j

Page 20: Tracheophytes - Vascular Plants

• Vascular tissue with branching capabilities.

• Includes lycophytes, pteridophytes, and seed plants.

Page 21: Seedless Vascular Plants

• Includes lycophytes and pteridophytes that possess vascular tissue but not seeds.

• Notable structures for nutrient and water conduction.

Page 22: Lycophytes and Pteridophytes

• Key Traits:

  • Moisture-dependent reproduction, capacity to produce more spores, robust sporophyte generation.

Page 23: Structural Features

• Plant Structures:

  • Stems, roots, leaves with specialized functions:

    • Roots: water and nutrient uptake.

    • Stems: support and production of leaves/sporangia.

    • Leaves: photosynthesis.

Page 24: Adaptations for Water Conservation

• Waxy Cuticle: prevents dehydration.

• Stomata: allows for gas exchange while minimizing water loss.

Page 25: Pteridophytes

• More recently diversified than lycophytes with over 12,000 species.

• Includes various fern species.

Page 26: Lycophytes

• Historically more diverse but now around 1,000 species.

• Includes club mosses, significant for coal formation.

Page 27: Plant Phyla Diagnostic Review

• Reemphasizing the classification of various plant types.

Page 28: Clade – Spermatophytes

• Innovated with seed evolution crucial for land plant survival.

• Includes both gymnosperms and angiosperms.

Page 29: Seed Evolution

• Seeds as multicellular structures with nutritional resources.

• Enable dormancy until conditions are favorable for germination.

• Seed plants produce pollen for gamete transport.

Page 30: Gymnosperms

• Defined by seed production without fruits.

• Include ginkgos and conifers, with seeds providing protection.

Page 31: Angiosperms

• Characterized by the presence of flowers and fruits.

• Enhance seed production and dispersal efficiency with endosperm for nutrition.

Page 32: Evolutionary Trajectories

• Observes changes in relative sizes and complexity of sporophytes versus gametophytes over time.

Page 34: Environmental Impact of Land Plants

• Land plants catalyzed the creation of soils, increased atmospheric oxygen, and influenced animal colonization of land.

Page 35: Atmospheric Changes

• Photosynthesis resulted in decreased atmospheric CO2, altering climate conditions.

Page 36: Ecological Contributions

• Early plants enriched soil and provided organic matter, influencing modern climate stability.

Page 37: Coal Age Forests

• Summary of past extensive forest ecosystems composed of diverse lycophytes and pteridophytes collapsing into coal deposits.

Page 38: Oxygen and Insect Evolution

• Larger insects thrived due to elevated oxygen levels, while climatic shifts favored seeded plant proliferation.

Page 39: Phylogenetic Traits

• Overview of traits distributed between algal and land plants, emphasizing shared and derived characteristics.