Plants
Understanding PlantsMs. Moore8/30/12
What is a Plant?Plants are:MulticellularEukaryotesPhotosynthesis using chlorophyll Most are autotrophs (some can be parasites or saprobes that live on decaying material)
Fossil evidence: 470 million years ago
Typical Plant CellWhat is unique to a plant cell?
Plant Life Cycle2 alternating phasesSporophyte: spore-producing plant; occurs in diploid (2N) phaseGametophyte: gamete-producing plant; occurs in haploid (N) phase
Survival on LandWhat do plants need to survive?SunlightWater and MineralsGas Exchange (O2 and CO2)Movement of Water and Nutrients
Evolved from an organism much like the multicellular green algae living today.
Plant KingdomBotanists group based on 3 features:Water-conducting tissuesSeedsFlowers
Botanists have 4 groups:Flowering plants: 235,000 speciesMosses and relatives: 15,600 speciesFerns and their relatives: 11,000 speciesCone-bearing plants: 760 species
BryophytesBryophytes: non-vascular plantsex.: moss, liverworts, and hornworts
Life cycles depend on water for reproduction because they lack vascular tissue (use osmosis)
Groups of BryophytesMossesAbundant in areas with water: swamps and bogs, near streams, and in rain forestsRhizoids: long, thin cells that anchor them in the ground and absorb water (no roots)LiverwortsLook like little green umbrellas Can reproduce asexually with gemmae (smal multicellular reproductive structures; can form a cup)HornwortsMuch like liverworts, except their sporophyte looks like a tiny green horn.
Life Cycle of BryophytesGametophyte is the dominant stage.
Dependence on water for fertilization to occursperm of bryophyte must swim to egg.
Protonema: mass of tangled green filaments that forms rhizoids; from germinated sporophyte
Antheridia: produces sperm
Archegonia: produces egg
Seedless Vascular PlantsVascular Tissue: transport system for water and nutrientsHave true roots, leaves, and stems
2 types vascular tissue:Xylem: carries water upward from rootsPhloem: transports nutrients and carbs produced from photosynthesis
Examples: ferns, club moss, horsetails
FernsHave characteristics of vascular plants: RootsRhizomesLeavesFronds
Life Cycle:Diploid sporophyte is dominant stage.Develop spores on underside of fronds in tiny containers: sporangia or groups called sori.
Seed Plants2 groups:Gymnosperms: bear seeds directly on the surfaces of conesAngiosperms: flowering plants; bear their seeds within a layer of tissue that protects the seed
Pollinationtransfer of pollen(male gametophyte) from male to female reproductive structure
Characteristics of a SeedSeed: embryo of a plant that is encased in a protective covering and surrounded by a food supply
Embryo: organism in early stage of development
Seed Coat: surrounds and protects embryo
GymnospermsInclude:GnetophytesCycadsGinkgoesConifers
AngiospermsCharacteristics:Develop flowers: unique reproductive organs; contain ovaries which protect seedsFruit: wall of tissue surrounding the seed (increases range of habitat)
Two Types: Monocot & DicotMonocots: Single cotyledonParallel veinsFloral: multiples of 3Vascular bundles throughout stemFibrous roots
Dicots:Two cotyledonsBranched veinsFloral: multiples of 4/5Vascular bundles in ringTaproot (carrot)
Life SpanAnnuals: complete one life cycle within one growing seasonEx: marigolds, petunias, pansies, wheat, cucumbers
Biennials: 2nd year produce flowers and seeds then die!Ex: evening primrose, parsley, celery, foxglove
Perennials: live for more than 2 yearsHerbacious: peonies, asparagus, grasses Woody: palm trees, maple trees, honeysuckle