Chapter 29 Friday March 4 2016 2 12 PM Chapter 29 Plant Diversity From Water to Land Algal Ancestry o 29 2 o Green algae and plants share Multicellularity descendent from multicellular organisms Cell walls with cellulose Chloroplasts with same pigments Storage molecule is starch o Charophytes and plants also share Certain cellular homologies see book Sporopollenin protective coating For zygotes in charophytes For spores in plants Plant Derived Characteristics o Alternation of generations Brown algae and some green algae Charophytes have 13 6c Sporophyte 2n of plants increases of unique offspring per fertilization o Walled haploid spores Dispersal thru air sporopollenin protects Made within multicellular sporangia o Multicellular gametangia Protecting sperm within antheridum REC Egg protected within archegonium Fertilizaiton here forming zygote o Sporophte embryos grow protected within female gametophyte Nourished via placental transfer cells o Apical meristems Meristem cells keep dividing Continuous growth toward resources o Waxy cuticle Waxy coat stops desiccation Pores needed to allow CO2 O2 exchange Controllable stomata in most plants o Secondary compounds Chemicals that deter competitors herbivores and parasites o Mychorrhizae 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 Plants o One bryophyte like ancestor of all plants About 470 million years ago o Key adaptations led to major plant groups Bryophytes Nonvascular Plants What are the Bryophytes o Liverworts Phylum Hepatophyta Leaves don t have vascular tissues o Mosses Phylum Bryophyta o Hornworts Phylum Antherocerophyta Bryophyte Characteristics o Haploid 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 o Diploid sporophyte depends on gametophyte for food and water Grows within archegonium of gametophyte Sporangium makes many haploid spores Moss Life Cycle Ecological Importance o Pioneer species in poor soils o Major producers in cold or high regions Sphagnum peat moss bogs important wetlands o From unbranched to branching sporophytes From 1 to many sporangia o Vascular 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 o Sporophyte photosynthesis increases Improved access to light many stems No longer depends on gametophyte for food o Roots evolve from underground stems Anchor larger plant o o o Absorb water and minerals Mycorrhizae helped Phototropism going toward the light Leaves evolve from branched stems Microphylls first single vein Today still and only present in Lycophytes Megaphlls later branched veins Today in Monilophytes and seed plants Sporangia shift to leaves sporophylls Sori clusters of sporangia on sporophylls Strobilous cone like group of sporophylls Seedless 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 Lycophytes o Relict 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 strobilus Microphylls Located at the bottom Include club moss and spike moss Little economy ecological importance today Ex Strobilus Ex Club mosses Ex Resurrection plant a spike moss Phylum Monilophyta Monilophytes o Formerly Pterophytes Whisk ferns Dichotomous branching No true leaves or roots lost secondary Horsetails Jointed stems and tiny leaves Strobili o Non branching stems hollow small leaves at joints deposits of silica along stem Ferns The most widespread and diverse Monilopytes o Large megaphylls Ex Fiddlehead Large 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 plant o Ferns mosses grow as epiphytes Some tree sized ferns today Fern Life Cycle Diploid sporophyte Sorus Sporangium Spore Germinating spore Developing gametophyte Upperside underside Young sporophyte gametophyte The Fern Life Cycle Goes through mitotic Dispersal in flowering plants importance o Dispersal plants cannot move so it is the process of spreading out the offspring to new locations o Importance to have a process of spreading out colonizing more land o Individual success so there will be no overcrowding offspring has a better chance of survival o Spreading 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 spores