Plants The Kingdom Plantae Common characteristics 1. Multicellular 2. Eukaryotic 3. Photoautotrophic First: Some terms to know • Gametophyte: a multi-celled haploid body (stage) that produces haploid (n) gametes. • Zygote: a diploid body formed when gametes fuse at fertilization. • Sporophyte: a multi-celled diploid (2n) body that grows by mitosis from a zygote, produces spore-bearing structures. • Spores: resting structures, able to survive harsh conditions, germinate to form gametophytes. Adaptations to Land • • • • Root systems Shoot systems Vascular tissues Waxy cuticle for water conservation Properties of Plants • • • • • • Photosynthetic Plant cells have a cell wall (cellulose) Organs: roots, stems, leaves Sessile: non-mobile, stay in one place Indeterminate growth Life cycle: Gametophyte Sporophyte Milestones in Plant Evolution charophytes bryophytes lycophytes horsetails ferns cycads ginkgos conifers gnetophytes flowering plants seed plants plants with true leaves vascular plants land plants (closely related groups) The Non-Vascular Plants: Bryophytes • Small, nonvascular, non-woody • Gametophyte dominates life cycle; has leaf-like, stem-like, and rootlike parts • Usually live in wet habitats • Flagellated sperm require water to reach eggs Moss Life Cycle Development of mature sporophyte (still attached to gametophyte) Zygote Fertilization Diploid Stage Meiosis Haploid Stage Spores released male gametophyte tip Sperm Egg Male gametophyte female gametophyte tip Female gametophyte Vascular Plants • Majority of plants • Have internal tissues that carry water and solutes (Xylem and Phloem) • Two groups – Seedless vascular plants – Seed-bearing vascular plants Seedless Vascular Plants • Produce spores but no seeds • Main groups: Lycophytes Horsetails Ferns Life Cycle of a Fern Seedless Vascular Plants • Like bryophytes: – Live in wet, humid places – Require water for fertilization • Unlike bryophytes: – Sporophyte is free-living and has vascular tissues Rise of Seed-Bearing Plants • Seeds appeared about 360 million years ago • Seed ferns and gymnosperms were dominant at first • Angiosperms arose later Pollen • Pollen grains are sperm-bearing male gametophytes that develop from microspores • Allows transfer of sperm to egg without water • Can drift on air currents, or be carried by pollinators Seeds • Ovules are female reproductive structures that become seeds • Consist of: – Female gametophyte with egg cell – Nutrient-rich tissue (endosperm) – Jacket of cell layers that will form seed coat Seed-Bearing Vascular Plants • Gymnosperms arose first – Conifers – Others… • Angiosperms arose later – Monocots – Dicots Special Traits of Seed-Bearing Plants • Pollen grains – Arise from microspores – Develop into male gametophytes – Can be transported without water • Seeds – Megaspores inside ovules – Embryo sporophyte inside nutritive tissues and a protective coat – Can withstand hostile conditions Gymnosperms • Plants with “naked seeds” • Seeds don’t form inside an ovary • Four groups Conifers Ginkgos Cycads Gnetophytes Conifer Characteristics • Widest known, largest number of living species • Woody trees or shrubs • Most are evergreen • Bear seeds on exposed cone scales • Most produce woody cones Pine Cones • Woody scales of a “pine cone” are the parts of where megaspores formed and developed into female gametophytes • Male cones, where microspores and pollen are produced, are not woody Pine Cones Male and female cones Pine Life Cycle Female cone Sporophyte (Pine Tree) Ovule Male cone Seed Pollen sac Fertilization Egg Pollen tube View inside ovule Meiosis Microspores Megaspores Angiosperms • Flowering plants • Defining feature: Ovules and (after fertilization) seeds are enclosed in an ovary • Two classes: Monocots and Dicots Flower Parts Pollination by animals Life Cycle of Angiosperms Vascular Tissues Xylem = absorbs water and nutrients up through the roots - movement only in the upward direction Phloem = distributes sugars, amino acids, & organic nutrients - movement is multi-directional Monocots vs. Dicots • • • • • Monocots 1 cotyledon Parallel veins Fibrous root Flower parts in 3’s Stem organization: - Scattered bundles • • • • • Dicots 2 cotyledons Net-like veins Tap root Flower parts in 4’s / 5’s Stem organization: - Bundles in a ring Monocots vs. Dicots Monocots vs. Dicots A Fungus is Not a Plant There are many significant differences between fungi and plants, including – fungi are hetertrophs – fungi have filamentous bodies (Hyphae, Mycelium) – fungi have nonmotile sperm – fungi have cell walls made of chitin – fungi have nuclear mitosis Many fungi produce spores.