Introduction to Introduction to PlantsPlants

Plant Plant CharacteristicsCharacteristics

Plants have 4 Plants have 4 characteristics characteristics that they all that they all share:share:

(1) (1) PhotosynthesisPhotosynthesis– Plants are Plants are greengreen

because they because they contain contain chlorophyllchlorophyll

– ChlorophyllChlorophyll: : green pigment green pigment that captures that captures energy from energy from sunlight, found in sunlight, found in chloroplastschloroplasts

– Plants use energy Plants use energy from sunlight to from sunlight to make food from make food from carbon dioxide carbon dioxide and water—this and water—this process is known process is known as as photosynthesisphotosynthesis

– Plants are Plants are producersproducers—they —they make their own make their own foodfood

(2) Cuticles(2) Cuticles– Plants don’t Plants don’t dry dry

outout because they because they are protected by are protected by a cuticlea cuticle

– CuticleCuticle: a waxy : a waxy layerlayer that coats that coats most of the most of the surfaces of surfaces of plants that are plants that are exposed to airexposed to air

(3) Cell Walls(3) Cell Walls– Plants do not have a Plants do not have a

skeletonskeleton like animals like animals– They stay upright They stay upright

and are protected and are protected because they are because they are surrounded by a surrounded by a rigid cell rigid cell wallwall

– Cell wall is made of Cell wall is made of carbohydrates and carbohydrates and proteinsproteins

– Some plants form a Some plants form a secondary cell wallsecondary cell wall this stops them from this stops them from growing largergrowing larger

(4) Reproduction(4) Reproduction– Plants have Plants have 22 stages in their life cycle: stages in their life cycle:

sporophyte stagesporophyte stage and and gametophyte stagegametophyte stage– In the sporophyte stageIn the sporophyte stage plant makes plant makes

sporesspores– In suitable environment, spores grow & In suitable environment, spores grow &

these new plants are called these new plants are called gametophytesgametophytes

– During gametophyte stage, female During gametophyte stage, female gametophytes produce gametophytes produce eggseggs and male and male gametophytes produce sperm.gametophytes produce sperm.

– Sex cells cannot Sex cells cannot growgrow directly into new directly into new plants—a sperm must fertilize an eggplants—a sperm must fertilize an egg

– The fertilized egg grows into a sporophyte, The fertilized egg grows into a sporophyte, makes more spores, and the cycle starts makes more spores, and the cycle starts againagain

Check for Check for UnderstandingUnderstanding

What are 4 characteristics that What are 4 characteristics that all plants share?all plants share?

Photosynthesis, cuticle, cell wall, Photosynthesis, cuticle, cell wall, and reproductionand reproduction

4 Main Groups of Plants4 Main Groups of Plants First they can be classified as nonvascular First they can be classified as nonvascular

plants and plants and vascularvascular plants plants Vascular plants are further divided into Vascular plants are further divided into 33

groups:groups:– (1) seedless plants(1) seedless plants– (2) nonflowering (2) nonflowering seedseed plants (gymnosperms) plants (gymnosperms)– (3) flowering seed plants ((3) flowering seed plants (angiospermsangiosperms))

Seedless PlantsSeedless Plants

***2 groups of plants don’t make seeds:***2 groups of plants don’t make seeds: (1) Nonvascular Plants(1) Nonvascular Plants

– Three groups of plants that lack specialized Three groups of plants that lack specialized conductingconducting tissues and true roots, tissues and true roots, stemsstems, and , and leavesleaves

– Depend on Depend on diffusiondiffusion to move materials from one to move materials from one part of plant to anotherpart of plant to another

– Most are Most are smallsmall– Usually live in Usually live in dampdamp places places– Don’t have true stems, roots, or leavesDon’t have true stems, roots, or leaves

– 3 groups of nonvascular plants are 3 groups of nonvascular plants are liverworts, hornworts, and liverworts, hornworts, and mossesmosses

liverworts hornworts mosses

Mosses, Mosses, Liverworts, and Liverworts, and HornwortsHornworts

– Have leafy stalks and Have leafy stalks and rhizoidsrhizoids

– RhizoidRhizoid: a rootlike : a rootlike structure in structure in nonvascular plants nonvascular plants that holds the plants that holds the plants in place and helps in place and helps plants get water and plants get water and nutrientsnutrients

– Have 2 stages to their Have 2 stages to their life cyclelife cycle

– Importance of Nonvascular PlantsImportance of Nonvascular Plants Usually the first plants to live in a new Usually the first plants to live in a new

environment, such as newly exposed environment, such as newly exposed rockrock

When they die, they form a thin layer of When they die, they form a thin layer of soilsoil

Hold soil in place, reducing Hold soil in place, reducing erosionerosion Some animals eat nonvascular plantsSome animals eat nonvascular plants Other animals use them for Other animals use them for nestingnesting

materialmaterial Peat mosses are important to humans Peat mosses are important to humans

because they can be dried out and because they can be dried out and burned as burned as fuelfuel

(2) Seedless (2) Seedless Vascular PlantsVascular Plants– Ferns, horsetails, and Ferns, horsetails, and

club mosses are club mosses are usually much smaller usually much smaller than in the past—than in the past—some ferns grew 8 some ferns grew 8 meters tall in ancient meters tall in ancient forests!forests!

– Because they have Because they have vascular tissues, they vascular tissues, they are often larger than are often larger than nonvascular plantsnonvascular plants

FernsFerns– Have a Have a rhizomerhizome

an underground an underground stem from which stem from which leaves and roots leaves and roots growgrow

– Fern leaves are Fern leaves are called “called “frondsfronds””

– -The end of the -The end of the fronds are called fronds are called fiddle headsfiddle heads

Club MossesClub Mosses– Have Have vascularvascular tissue, so tissue, so

not actually a mossnot actually a moss HorsetailsHorsetails

– Stems are hollow and Stems are hollow and contain contain silicasilica—gives —gives them gritty texturethem gritty texture

– Early Americans used Early Americans used horsetails to scrub pots horsetails to scrub pots and pansand pans

– Importance of Seedless Vascular PlantsImportance of Seedless Vascular Plants Help form soil & prevent erosionHelp form soil & prevent erosion Ferns add to soil depth, helping other Ferns add to soil depth, helping other

plants to growplants to grow Popular Popular houseplantshouseplants Fiddleheads of ferns and some horsetails Fiddleheads of ferns and some horsetails

can be can be eateneaten Horsetails are used in some dietary Horsetails are used in some dietary

supplements, shampoos, and skin-care supplements, shampoos, and skin-care productsproducts

Remains of ancient ferns, horsetails, and Remains of ancient ferns, horsetails, and club mosses form club mosses form coalcoal, which humans , which humans rely on for rely on for energyenergy

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Name & describe the 4 main Name & describe the 4 main groups of plantsgroups of plants

1)nonvascular: no specialized tissues1)nonvascular: no specialized tissues

2) Seedless vascular: ferns, 2) Seedless vascular: ferns, horsetails, club mosseshorsetails, club mosses

3) Gymnosperms: nonflowering seed 3) Gymnosperms: nonflowering seed

4) Angiosperm: flowering seed4) Angiosperm: flowering seed

The Origin of PlantsThe Origin of Plants– Green algae may look like a Green algae may look like a plantplant, but it , but it

isn’t a plantisn’t a plant– Scientists think that green algae and plants Scientists think that green algae and plants

share a share a common ancestorcommon ancestor because of the because of the following similarities:following similarities: Both have the same kind of chlorophyllBoth have the same kind of chlorophyll Have similar Have similar cell wallscell walls Both use photosynthesis to make own Both use photosynthesis to make own

foodfood Both store energy in form of Both store energy in form of starchstarch Both have a Both have a twotwo-stage life cycle-stage life cycle

The similarities between a modern green algae (right) and plants, such as ferns

(left), suggest that both may have originated from an ancient species of

green algae.

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Explain the origin of plantsExplain the origin of plants

-scientists think that green algae -scientists think that green algae and plants share a common and plants share a common

ancestorancestor