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