Plant CharacteristicsMost have roots or root like structures to holdthem in the ground.Are adapted to nearly every environment onEarth.All plants need water.All are many-celled.Nearly all contain chlorophyll.
Plant CellsA cell membrane, cell wall,nucleus, and othercellular structures.Cell walls provide structure and protection forplant cells.Most plant cells contain chlorophyll (greenpigment that gives plants their color).Chlorophyll is needed for photosynthesis.Chlorophyll is found in the chloroplast.
Plant CellsMost have a large, membrane-bound structurecalled the central vacuole that takes up most ofthe space inside of the cell.Central vacuole regulates water content of cell.Also stores pigment that makes some flowersred, blue, or purple.
Protection and SupportCuticle – waxy, protective layer secreted bycells onto surface of plant and slows the loss ofwater.Cellulose – chemical compound found in cellwalls that connect to make long fibers to helpprovide support and structure.
Evolution of PlantsBetween 260,000 and 300,000 species havebeen identified (are probably many more).Ancestors of plants was probably green algae.Oldest fossil plants are about 420 million yearsold.Cone-bearing plants (pine trees) – 300 millionyears agoFlowering plants – 120 million years ago (but notfor sure).
Classification of PlantsVascular – plants with tubelike structures thatcarry water, nutrients, and other substancesthroughout the plant.Nonvascular – do NOT have tubelike structuresand use other ways to move water andsubstances.All plants have a binomial nomenclature.
Seedless Nonvascular PlantsDo NOT grow from seedsNo roots – have rhizoids (threadlike structuresthat anchor them into the ground)Only 2-5 cm tallNo tubelike structures to move water through itNo flowers or conesEx. – moss, liverworts, hornworts
Examples of Seedless NonvascularMosses– Most seedless nonvascular are classified as this– Leaflike growths are arranged around a central stalk.– Grow on tree trunks and rocks
Examples of Seedless NonvascularLiverworts – Means “herb for the liver” – Used as medicine long ago – One-celled rhizoids
Examples of Seedless NonvascularHornworts– Less than 2.5 cm in diameter– Flattened body– Only 1 chloroplast in each cell
Reproduction of Nonvascular PlantsGametophyte (sex organs) – structure thatforms gametes (sperm cells and egg cells).Sperm are formed in the male gametophytesand eggs are formed in the tips of femalegametophytes.Sperm is splashed by water onto femalegametophytes and swims to the eggs.Sperm joins with an egg and a zygote is formed.
Reproduction of Nonvascular PlantsZygote develops into a long, thin stalk from thetip of the female gametophyte.A capsule forms at the top of this stalk.Spores are formed inside the capsule.The capsule and the stalk are called thesporophyte.Capsule bursts open and spores are forced out.If spores land on a moist surface, they will growinto another plant.
Nonvascular Plants and the EnvironmentSpores of mosses and liverworts are carried bythe wind and will grow into plants if enoughwater is available.Often are pioneer speciesPioneer species – first plants to grow in new ordisturbed environments (lava fields, forest fire)
Seedless Vascular PlantsHave tube like cells of vascular tissue thatmoves water and nutrients through the plant.Grow larger than nonvascular plants b/c thevascular tissue distributes water and nutrients.Ex. – ferns, ground pines, spike mosses,horsetails.Ferns – largest group of seedless vascularplants
FernsAt least 12,000 knownspeciesHave stems, leaves, androotsLeaves are calledfronds.Spores are produced instructures that areusually found on theunderside of the fronds.
Club MossesHave needle likeleavesSpores are producedat the end of thestems in structuresthat look like tiny pinecones.
HorsetailsStem is jointed and has ahollow center surroundedby a ring of vasculartissue.At each joint, leavesgrow out from around thestem.Pull on a stem, will popapart in sections.Used for polishingobjects and sharpeningtools
Importance of Seedless PlantsPeat – compresseddecaying plants – usedas low-cost fuel in placeslike Ireland and Russia.Peat supplies about 1/3of Ireland’s energyrequirements.
Characteristics of Seed PlantsMost plants identified so far are seed plants.Classified into 2 major groups – gymnospermsand angiospermsSeed plants are vascular
Characteristics of seed plantsLeaves – where photosynthesis usually occursMany different shapes, sizes, and colors
Characteristics of seed plantsLeaf cell layers– epidermis (upper and lower surface)– stomata – small openings in epidermis that allows oxygen, water, and carbon dioxide to enter and leave the cell.– Guard cells – 2 found around each stoma that opens and closes it
Characteristics of seed plantsStems – located above ground and supportbranches, leaves, and flowers.Materials move between leaves and rootsthrough vascular tissue in the stem.Can be herbaceous (soft and green) or woody(hard and rigid)
Characteristics of seed plantsRoots – water andother substancesenter through rootsAct as anchors(hold plants in theground)Store food
Characteristics of seed plantsVascular Tissue – 3 typesXylem – hollow, tubular cells that are stacked upon oneanother to form a vessel. These vessels transportwater and substances from the roots to the rest of theplant. Also help support plant.Phloem – tubular cells that are stacked to form tubes.Move food from where it’s made to other parts of theplant.Cambium – tissue that produces most of xylem andphloem cells.
GymnospermsOldest trees alive are gymnosperms and mostgymnosperms are conifers (trees that producecones).Gymnosperm – vascular plants that produceseeds NOT protected by fruit.Do NOT have flowersLeaves are needle like or scale like.Many gymnosperms are called evergreensbecause some leaves always remain on theirbranches.
Reproductive Process of GymnospermsConifers produce seeds on the woody scales ofcones.Female cones have spiral woody scales on ashort stem. Eggs are formed in 2 ovules on thetop of each scale.Male cones are much smaller and less woodythan the female. They produce large amounts ofpollen.Pollen is released and may land on female coneand fertilizes the eggs.
AngiospermsFlowering plantsVascular plants that produce seeds inside fruits,which form flowers.Root systemShoot system – stem and leavesFlowers develop from the shoot system.
Parts of an AngiospermPistils – female reproductive organOvary – located at the base of the pistilOvules – structures that contain eggsStigma – sticky top part of the pistil
Parts of an AngiospermStyle – a stalk that connects the ovule to thestigma.Stamen – male reproductive organFilament – stalk found in the stamenAnther – on top of filament where pollen isformed.Petals – surround the pistils and stamens –attract pollinators
Reproduction Process ofAngiosperms (sexualreproduction)
PollinationOccurs when pollen grains from theanthers are carried by water, wind, oranimals to the stigma.When a pollen grain lands on the stickystigma, a tube grows downward throughthe style, into the ovary, and into the ovule.
Other types of PollinationWhen pollen from When pollen from athe anther of a flower on one plantflower on one plant lands on the stigmalands on the stigma of the same flowerof a flower from or on the stigma ofanother plant, it is another flower oncalled cross- the same plant, it ispollination. called self- pollination.
FertilizationOccurs when a sperm cell from the pollen grainmoves down through the pollen tube and fuseswith an egg cell in the ovule.Zygote is formed when the sperm cell and eggcell join.Zygote then develops into an embryo (younggrowing plant).
FertilizationAs the embryo grows, the outer layers of the ovulebecome tough and form a seed coat.Seed coat protects the embryo after it is released intothe environment.Seed – consists of the embryo, stored food, and seedcoat.Ovary that surrounds a seed or seeds gets larger anddevelops into the fruit.Fruit – ripened ovary of a flower that contains one ormore seeds.
Seed DispersalWhen seeds are usually carried away from theparent plant.Fruits assist in seed dispersal, as well as in seedprotection.
What’s inside a seed?Cotyledon – the young leaves in the embryo ofa seed.Monocot – seed embryos that contain onecotyledon (mono means “one”). Storednutrients for the growing embryo are located inthe endosperm (main part of a corn seed youeat).Dicot - seed embryos that contain 2 cotyledons(di means “two”). Stored nutrients in dicot seedsare located in the cotyledons. Cotyledons arethe main part of a bean seed you eat.
GerminationEarly growth of a new plant from the embryo in aseed.Monocot flowers – petals and sepals are inmultiples of 3, leaves are narrow and containparallel veins.Dicot flowers –petals and sepals are inmultiples of 4 or 5, leaves are broad and containbranched veins.
Other Types of ReproductionAsexual reproduction – reproduction by anyprocess that does NOT involve gametes (spermcells and egg cells).Vegetative propagation (type of asexualreproduction) – when a new plant can be grownfrom parts of other plants.
Life Cycles of Angiosperms Biennials – complete Perennials – take their life cycles within more than 2 years to 2 years. They only complete their life produce flowers and cycles. They produce seeds and flowers seeds during the 2 each spring. year of growth.Annuals – these must be grown from seeds each year.
Importance of Seed PlantsNo paper, no books, no pencils, no food if therewere no seed plants!!Most of the wood used for construction and forpaper production comes from conifers such aspine and spruces.Basis for diets of most animals.First plants that humans grew.Source of many fibers in clothing.