Chapter 29Friday, March 4, 20162:12 PM Chapter 29 - Plant Diversity From Water to Land-Algal Ancestryo[29.2]o"Green algae" and plants share:-Multicellularity (descendent from multicellular organisms)-Cell walls with cellulose-Chloroplasts with same pigments-Storage molecule is starchoCharophytes and plants also share-Certain cellular homologies (see book)-Sporopollenin (protective coating)For zygotes in charophytesFor spores in plants-Plant Derived CharacteristicsoAlternation of generations-Brown algae, and some green algae-Charophytes have [13.6c]-Sporophyte (2n) of plants increases # of unique offspring per fertilizationoWalled haploid spores-Dispersal thru air: sporopollenin protects-Made within multicellular sporangiaoMulticellular gametangia-Protecting sperm within antheridum (REC)-Egg protected within archegoniumFertilizaiton here: forming zygoteoSporophte embryos grow protected within female gametophyte-Nourished via placental transfer cellsoApical meristems-Meristem cells keep dividing-Continuous growth toward resourcesoWaxy cuticle-Waxy coat stops desiccation-Pores needed to allow CO2/O2 exchangeControllable stomata in most plantsoSecondary compounds-Chemicals that deter competitors, herbivores, and parasitesoMychorrhizae-(Association with plant roots (myco - fungi (rrhiz - roots))-Mutualism with fungi; helps water and mineral absorption-Dates back to first land plants (before true roots)-Diversification of PlantsoOne bryophyte-like ancestor of all plants-About 470 million years agooKey adaptations led to major plant groups Bryophytes - Nonvascular Plants-What are the Bryophytes?oLiverworts - Phylum Hepatophyta-Leaves don't have vascular tissuesoMosses - Phylum BryophytaoHornworts - Phylum Antherocerophyta-Bryophyte CharacteristicsoHaploid gametophyte is dominant form-Dominant - Majority of life is gametophyte form-Gametophyte - plant form that makes gametesMakes eggs and flagellated spermMost are small, low growing, moist areas-This is because they don't have vascular tissues-Lacks vascular and supportive tissue-Very thin body: depends on diffusion-With rhizoids (rhiz - root, oid - like = rootlike) for attachment (not true roots)oDiploid sporophyte depends on gametophyte for food and water-Grows within archegonium of gametophyte-Sporangium makes many haploid spores-Moss Life Cycle-Ecological Importanceo"Pioneer" species in poor soilsoMajor producers in cold or high regions-Sphagnum "peat moss" bogs: important wetlandsoFrom unbranched to branching sporophytes-From 1 to many sporangiaoVascular tissues support taller ,stem shows specialized vascular tissues(helps make plants a larger size)-Continuous, branching bundles of tubular cells connected end-to-end-Provides bulk flow over longer distances-Adds support-Phloem moves sugars and organic products-Xylem carries water and minerals (dead cells)Most vascular plants have tracheids with walls strengthened by tough polymer lignin (hard durable material)oSporophyte photosynthesis increases-Improved access to light; many stems-No longer depends on gametophyte for foodoRoots evolve from underground stems-Anchor larger plant-Absorb water and minerals-Mycorrhizae helpedPhototropism - going toward the lightoLeaves evolve from branched stems-Microphylls first single veinToday still (and only) present in Lycophytes-Megaphlls later: branched veinsToday in Monilophytes and seed plantsoSporangia shift to leaves: sporophylls-Sori = clusters of sporangia on sporophylls-Strobilous = cone-like group of sporophyllsoSeedless vascular plants changed the Paleozoic world-Covered the earth, increasing organic C on land for food-Further increases in O2 levels-Reduces CO2 levels-All favoring success of land animals-Tree-size seedless forests in Carboniferous swamps (later Paleozoic Era) formed today's coal deposits Extant Seedless Vascular Plants-Phylum Lycophyta: LycophytesoRelict group-Closest group to ancestral vascular plants (have ancestral characteristics) - for ex.Only have microphylls no megaphylls, no seeds, produce spores, spores made on microphylls, makes strobili-All now very small-With microphylls (no megaphylls) and strobili Strobilus-Cone-like strobilusMicrophylls-Located at the bottom-Include club moss and spike moss-Little economy/ecological importance today-Ex. Strobilus-Ex. Club mosses-Ex. Resurrectionplant - a spike moss -Phylum Monilophyta: Monilophyteso(Formerly Pterophytes)Whisk ferns-Dichotomous branching-No true leaves or roots (lost secondary)-Horsetails-Jointed stems and tiny leaves-StrobilioNon-branching stems, hollow, small leaves at joints, deposits of silica along stemFerns-The most widespread and diverse Monilopytes-Large megaphylls-Ex. FiddleheadoLarge leaflets-Sori on underside of sporophylls-Sori-Sporophyll-Sporangium-One sorus with sporangia-Mostly in understory or as epiphytes-Low-growing-“Epiphyte” = grows on the surface of a plantoFerns, mosses grow as epiphytes-Some tree-sized ferns todayFern Life CycleDiploid sporophyteSorusSporangium-Spore Germinating spore-Developing gametophyteUpperside/undersideYoung sporophyte/gametophyte The Fern Life Cycle-Goes through mitotic -Dispersal in flowering plants - importance:oDispersal - plants cannot move, so it is the process of spreading out the offspring to new locationsoImportance to have a process of spreading out - colonizing more landoIndividual success - so there will be no overcrowding, offspring has a better chance of survivaloSpreading out - genetically variable spores spread out in many different places as possible, some will survive -Because of different environment-Some will survive but some will not-Success through genetically variable