Transcript Plantae
Domain Eukarya Kingdom Plantae What makes a plant a plant? • Cell wall primarily of cellulose • Starch as primary photosynthetic storage product • Multicellular with complex specialized tissue development • Chl a, Chl b, xanthophylls, carotenoids Plant evolution simplified Radiates from simple to more complex – in both form and environments • Seedless non-vascular • Seedless vascular • Seed producing, vascular • Seed producing, vascular, fruits/flowers Semi-aquatic to more terrestrial • Ancestral “plants” transitions to primitive plants – Requirements met from aquatic environment • Gas, water, light, buoyancy support • Complex plants – Adapt to two environments • Shoot system • Root system Plants: categorized by structures and lifecycles… Alternation of Generations Moss sporophytes and gametophytes sporophytes gametophytes Moss antheridia Sperm Moss antheridia w/sperm Moss archegonia ovum Moss archegonia 2 ova Moss archegonia 3 Moss sporophytes Operculum Moss capsule (sporophyte) Spores Liverwort Liverwort antheridiophore Liverwort antheridiophore 2 Liverwort antheridia Antheridiophore sperm Liverwort antheridia w/sperm Liverwort archegoniophore Liverwort archegonia w/ova Archegoniophore ovum Archegonium Liverwort sporophyte Archegoniophore Liverwort sporophyte 2 spores Liverwort gemmae cups(cupules) Gemmae cups (cupules) Gemma cup (cupule) gemma Hornwort sporophytes gametophyte Hornwort 2 “Horn –like” Sporophyte gametophyte Tracheophytes • Ferns and “fern allies” • Seedless • Vascular plants – Xylem composed of Tracheids – tapered porous cells • capillary action moderately efficient • Sporophyte dominant ancestral e.g. Rhyniophyta Psilophyta Psilophyta gametophyte Lycophyta strobila leaves Lycophyta strobilus microspores sporophylls megaspores Lycophyta strobilus 2 Megaspores megsporangium Microspores Lycophyta gametophyte Sphenophyta strobilus Sphenophyta strobilus Sphenophyta gametophyte Pterophyta sporophyte Pterophyta sporophyte2 Fern frond w/ sori Sori on fern leaflets Sorus Fern sporangia Spores Annulus Sporangium Fern sporangia and spores Fern gametophyte Fern gametophyte Gametophyte w/antheridia Gametophyte (prothallus) Antheridia sperm Antheridia w/sperm Antheridium sperm Gametophyte w/archegonia Archegonia Gametophyte w/archegonia 2 Archegonia Archegonia on surface of prothallus Fern sporangium and prothallus Sporophyte Gametophyte (prothallus) Fern Life Cycle Seed producing plants Gymnosperms • Sporophyte dominant • Conifers & relatives • Heterosporous Angiosperms • Sporophyte dominant • Flowering plants • Heterosporous – Mega- and micro– Small gametophye matures in protected cones – Mega- and micro– Small gametophye matures in protected flowers • Female in ovulate cones • Male in staminate cones • Female in flower ovary • Male in flower anthers – Wind blown-pollen • Seeds protected in ovulate cone – Dispersed by wind, animal, water sometimes – Animal pollination and some wind-blown • Seeds protected in fruit – Dispersed by animal mostly Seed? • • • • Ovule to seed Ovule: sporophyte tissue surrounding sporangia Seed coat: protective diploid tissue Embryo: diploid zygote develops to sporophyte Endosperm: nutritive tissue surrounding embryo to feed it until it can photosynthesize on its own Evolutionary importance of Seeds • These plants produce pollen – Pollen produces sperm nuclei (no water requrd) • Expand over drier habitats – Very protective over seasons (dormancy) • Endosperm (embryonic food) – headstart • Seed dispersal not dependent on water – Collected and distributed further • Flowering plants…even further in fruits Pine lifecycle a Pine lifecycle b Pinus staminate cones Pinus Ovulate cone (mature) Staminate cone with pollen Pollen grains (microspores or micorgametophytes) Pinus microgametophytes (mature pollen grains) “Wing” Tube nucleus Generative nucleus Pinus ovulate cone ovule megasporophyll Pinus megasporophyll Megaspore mother cell Megasporophyll Ovule w/megaspore mother cell Megaspore mother cell Ovule Pinus Megagametophyte Ovule Ovum Pollen tubes Pollen tube 2 Ovule (megagametophyte) Pinus seed Haploid endosperm (gametophyte tissue) Cycadophyta (male) Cycadophyta Cycadophyta ovulate cones Ginkgophyta Ginkgophyta leaves Ginkgo ovules/seeds (naked) ovules (naked) seeds Ginkgo staminate cones Gnetophyta Welwitschia mirabilis • found in Angolan desert • “desert onion” Gnetophyta/Ephedra Angiosperms /Anthophyta • • • • Flowering Plants (anth = flower) Seeds in a fruit (angio = container) Double fertilization (see life cycle) Like other pollen producers, is not dependent on water for fertilization What is a flower? Flower structure (corolla) (carpel) (calyx) Plants: • Monecious – Has both sexes • Dioecious – Separate sexed plants Flowers: • • • • • • • Perfect Imperfect Complete Incomplete Regular Irregular Inflorescences Inflorescences Anther1 Anther 2 Dehiscing anther Pollen grains Angiosperm lifecycle Mature pollen grains Lilium ovary (immature) Lilium ovule ovule Megagametophyte (embryo sac) funiculus A= plumule B= hypocotyl Dicot Seed C = cotyledon D = testa E = radicle E Dicot seed germination Radicle Monocot seed Embryo Testa Cotyledon Endosperm Plumule Radicle Monocot seed germination Vascular tissue • Transport water, nutrients and food between roots and shoots • System of xylem and phloem cells • Varied organization in roots & shoots Xylem cells – mature cells that become lignified (thickened 2o cellulose), dies, and perforates from lysosomes • Tracheids – Primitive vascular plants – Tapered, pits on ends, less capillary action vs. vessel elements • Vessel elements – – – – Less primitive vascular plants Pits on sides, open ends Stacked to form long tubes Advanced capillary action • Transpiration – Roots → shoots → leaves → out – Via: root pressure and diffusion, capillary pressure, negative pressure of evaporation and cohesion Phloem cells – living cells that transport sugars (sap) • Sieve tubes – no nucleus nor organelles – Open sieve plates • Companion cells – Nucleated – Adjoined to sieve tubes via plasmodesmata – Controls sieve tubes; regulates movement • Translocation – Movement of sugars; sources to sinks leaves → roots, fruits, &/or meristems Plant Structure • Apical meristem – Mitotic division – Stem & root tips – Primary growth (length) • Ground meristem – Mitotic division – Ground tissues: • Parenchyma – large; storage • Collenchyma – smaller; flexible support • Schlerenchyma – lignified; rigid support; woody • Cambium – Mitotic secondary growth – e.g. Vascular cambium – e.g. Cork cambium Leaf bud Ground meristem Leaf bud 2 Apical meristem Ground meristem Provascular tissue Monocot root • Vascular bundles centered in roots • Cortex = outer layer • Pith = center tissue • Stele = pith + vascular tissue Dicot root Monocot root 2 Parenchyma Pith (Parenchyma) Monocot root 3 Endodermis Dicot root 2 Parenchyma Dicot root 3 Endodermis and casparian strip Pericycle Phloem Xylem Vascular cambium • Vascular bundles – Xylem, phloem, and cambium in between – Scattered throughout monocot stems – Organized around periphery of dicots • Cambium – Mitotic secondary growth – e.g. Vascular cambium – e.g. Cork cambium Monocot stem Monocot stem 2 Sclerenchyma Outside Phloem Sieve element Companion cell Xylem vessel Air space Inside Dicot stem Dicot stem 2 phloem sclerenchyma Vascular cambium Woody stem Summerwood Springwood Woody stem 2 Cork Vascular cambium Phloem Phloem ray Xylem Woody stem 3 Cork (collenchyma tissue) Vascular cambium Fruit – ripened ovary that protects the seeds • Ripened? • Layers of the ovary = Pericarp – Exocarp • Outer layer /ovarian wall – Mesocarp • Middle layer – Endocarp • Inner/adjacent to ovules Fleshy fruits • One or more ovarian layer is fleshy – Drupe • Endocarp is hardened; pit or stone • Peaches, nectarines, apricots, etc – Berry • All or most pericarp is fleshy • Grape, tomato, etc – Pepo • Berry with hard thick rind • Melons, pumpkins, etc – Hesperidium • Berry with leathery rind • Citrus – Pome • Swollen receptacle around ovary or core • Apple, pear Dry fruits • Lacks fleshy tissue – Dehiscent fruits • Split along a seam to disperse seeds • Legumes – two seams • Capsules – multiple seams • Bean, pea pods, peanuts, etc – Indehiscent • Do not split on a seam • Achenes, grains, nuts • Corn, wheat, etc • Simple fruits – Single ovary of one flower • Aggregate fruits – Many ovaries of one flower • Multiple fruits – Many ovaries of many clustered flowers (inflorescence) • Accessory fruits – Tissue other than ovary ripens (swollen) What is a coconut? Fleshy? Dry? Other? Drupe: a single fleshy fruit with a hard stone which contains the single seed Plant Hormones (Ch. 39) chemical communication and regulation • Auxins – Cell elongation – Apical dominance – Abscission suppression • Slows the shedding of leaves, flowers, fruits – Fruit maturation – Geotropism • Phototropism • Gravitropism A. The tips have been removed. No auxin is produced and the shoots do not grow longer. B. The tips have been covered so light cannot reach them. Auxin is in the same concentration on both sides of the shoots, so they grow longer evenly on both sides. C. One side of the tips are in more light than the other side. Auxin is in a greater concentration on the shaded side, causing the cells there to grow longer than the cells on the light side. Plant Hormones (Ch. 39) chemical communication and regulation • Giberellins – GA or Giberellic acid – Growth • Release some buds and seeds from dormancy • Dwarf plants lack GA – Spray on grapes = bigger grapes • Stem elongation – Spray on dwarf plants = taller plants • Related to flowering in some plants Sold as common bio-fertilizer Plant Hormones (Ch. 39) chemical communication and regulation • Cytokinins – Cell division – Stimulate bud growth – Stimulates fruit & embryo development – Prevents leaf senescence • Slows aging to decay With & without Plant Hormones (Ch. 39) chemical communication and regulation • Abscisic Acid – General growth inhibitor – Induces dormancy • Wintering of buds and leaves – Closure of stomata • Ethylene – Gaseous hormone – Plays role in fruit ripening – Fruit abscission • (shedding) – One of the reasons why ripe bananas will “ripen” other fruits