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.