Unit 7 PlantsUnit 7 Plants

Ch. 22 Plant DiversityCh. 22 Plant Diversity

What is a Plant?What is a Plant? Plants are multicellular eukaryotes that have Plants are multicellular eukaryotes that have

cell walls made of cellulosecell walls made of cellulose They develop from multicellular embryos & They develop from multicellular embryos &

carry out photosynthesis using the green carry out photosynthesis using the green pigments chlorophyll pigments chlorophyll aa & & bb

What Plants Need to SurviveWhat Plants Need to Survive The lives of plants center on the need for light, The lives of plants center on the need for light,

water & minerals, gas exchange, & the water & minerals, gas exchange, & the transport of water & nutrients throughout the transport of water & nutrients throughout the plant body plant body

What Plants Need to SurviveWhat Plants Need to Survive Plants use the energy from the sun to carry out Plants use the energy from the sun to carry out

photosynthesisphotosynthesis All cells require a constant supply of water, so All cells require a constant supply of water, so

plants must obtain & deliver water to their plants must obtain & deliver water to their cellscells

Plants require oxygen for cellular respiration, Plants require oxygen for cellular respiration, & carbon dioxide for photosynthesis& carbon dioxide for photosynthesis

Early PlantsEarly Plants For most of Earth’s history, plants did not For most of Earth’s history, plants did not

existexist The first plants evolved from an organism The first plants evolved from an organism

similar to the multicellular green algae living similar to the multicellular green algae living todaytoday

Early PlantsEarly Plants The oldest known fossils of plants are almost The oldest known fossils of plants are almost

450 million years old, 450 million years old, CooksoniaCooksonia, a moss plant, a moss plant

Overview of the Plant KingdomOverview of the Plant Kingdom The plant kingdom is divided into 4 groups The plant kingdom is divided into 4 groups

based on 3 features: water-conducting tissue, based on 3 features: water-conducting tissue, seeds, & flowersseeds, & flowers

Overview of the Plant KingdomOverview of the Plant Kingdom There are 235,000 flowering plant species, There are 235,000 flowering plant species,

almost 90% of all living species of plantsalmost 90% of all living species of plants

BryophytesBryophytes BryophytesBryophytes - includes:mosses, liverworts, & - includes:mosses, liverworts, &

hornworts, nonvascular plantshornworts, nonvascular plants Bryophytes have life cycles that depend on Bryophytes have life cycles that depend on

water for reproductionwater for reproduction Lacking vascular tissue, they can draw up Lacking vascular tissue, they can draw up

water by osmosis only a few centimeters water by osmosis only a few centimeters above groundabove ground

Groups of BryophytesGroups of Bryophytes Mosses are the most common, & grow in areas Mosses are the most common, & grow in areas

of water: swamps & bogs, etc.of water: swamps & bogs, etc. They lack vascular tissue, which means they They lack vascular tissue, which means they

do not have true rootsdo not have true roots RhizoidsRhizoids - long, thin cells that - long, thin cells that

anchor them in the ground & anchor them in the ground & absorb water & minerals from absorb water & minerals from surrounding soilsurrounding soil

Groups of BryophytesGroups of Bryophytes Liverworts are odd little plants that look like Liverworts are odd little plants that look like

flat leaves attached to the ground, some flat leaves attached to the ground, some species resemble the shape of a liverspecies resemble the shape of a liver

Groups of BryophytesGroups of Bryophytes Hornworts are generally found in soil that is Hornworts are generally found in soil that is

damp nearly year-rounddamp nearly year-round

Human Use of MossesHuman Use of Mosses In certain environments, dead sphagnum moss In certain environments, dead sphagnum moss

forms thick deposits of peatforms thick deposits of peat Peat can be cut from the ground & burned as Peat can be cut from the ground & burned as

fuel, or used in fuel, or used in gardening gardening becausebecause it can it can improve the improve the soil’s soil’s ability to ability to retain waterretain water

Seedless Vascular PlantsSeedless Vascular Plants Vascular tissueVascular tissue - specialized to conduct water - specialized to conduct water

& nutrients throughout the plant& nutrients throughout the plant

Evolution of Vascular Tissue: A Evolution of Vascular Tissue: A Transport SystemTransport System

TracheidsTracheids - thick cells that resist pressure, key - thick cells that resist pressure, key cells in xylemcells in xylem

XylemXylem - transport system that - transport system that carries water from roots to carries water from roots to every every part of a plantpart of a plant

PhloemPhloem - transports solutions - transports solutions of nutrients & carbs produced of nutrients & carbs produced by photosynthesisby photosynthesis

Evolution of Vascular Tissue: A Evolution of Vascular Tissue: A Transport SystemTransport System

Both forms of vascular tissue (xylem & Both forms of vascular tissue (xylem & phloem) can move fluids through the plant phloem) can move fluids through the plant body, even against the force of gravitybody, even against the force of gravity

LigninLignin - makes cell walls rigid, enables - makes cell walls rigid, enables vascular plants to grow upright & reach great vascular plants to grow upright & reach great heightsheights

Ferns & Their RelativesFerns & Their Relatives Seedless vascular plants that include: club Seedless vascular plants that include: club

mosses, horsetails, & fernsmosses, horsetails, & ferns Ferns have true roots, leaves, & stemsFerns have true roots, leaves, & stems RootsRoots - underground organs that absorb water - underground organs that absorb water

& minerals& minerals LeavesLeaves - photosynthetic organs that have 1 or - photosynthetic organs that have 1 or

more bundles of vascular tissuemore bundles of vascular tissue

Ferns & Their RelativesFerns & Their Relatives VeinsVeins - vascular tissue (xylem & phloem) - vascular tissue (xylem & phloem)

gathered togethergathered together StemsStems - supporting structures that connect - supporting structures that connect

roots & leaves, carrying water & nutrients roots & leaves, carrying water & nutrients between thembetween them

Club MossesClub Mosses Small plants that live in moist woodlands Small plants that live in moist woodlands The most common club mosses look like The most common club mosses look like

miniature pine trees, called “ground pines”miniature pine trees, called “ground pines”

HorsetailsHorsetails Named because its stems look Named because its stems look

similar to horses’ tailssimilar to horses’ tails During Colonial times, During Colonial times,

horsetails were commonly used horsetails were commonly used to to scour pots & pansscour pots & pans

FernsFerns Ferns have true vascular tissues, strong roots, Ferns have true vascular tissues, strong roots,

creeping underground stems (creeping underground stems (rhizomesrhizomes), & ), & large leaves (large leaves (frondsfronds))

Seed PlantsSeed Plants Seed plants are divided into 2 groups: Seed plants are divided into 2 groups:

gymnosperms & angiospermsgymnosperms & angiosperms GymnospermsGymnosperms - have their seeds directly on - have their seeds directly on

the surfaces of conesthe surfaces of cones AngiospermsAngiosperms - (flowering plants) - have their - (flowering plants) - have their

seeds within a layer of tissue that protects the seeds within a layer of tissue that protects the seedseed

Reproduction Free From WaterReproduction Free From Water Adaptations that allow seed plants to Adaptations that allow seed plants to

reproduce without water include flowers or reproduce without water include flowers or cones, the transfer of sperm by pollination, & cones, the transfer of sperm by pollination, & the protection of embryos in seedsthe protection of embryos in seeds

Reproduction Free From WaterReproduction Free From Water ConesCones - the seed-bearing structures of - the seed-bearing structures of

gymnospermsgymnosperms FlowersFlowers - the seed-bearing structure of - the seed-bearing structure of

angiospermsangiosperms

Reproduction Free From WaterReproduction Free From Water Pollen grainPollen grain - plant sperm - plant sperm PollinationPollination - the transfer of pollen from male - the transfer of pollen from male

reproductive structure to female reproductive reproductive structure to female reproductive structurestructure

Reproduction Free From WaterReproduction Free From Water SeedSeed - an embryo of a plant that is encased in a - an embryo of a plant that is encased in a

protective covering & surrounded by a food protective covering & surrounded by a food supplysupply

EmbryoEmbryo - an organism in its - an organism in its early stage of developmentearly stage of development

Reproduction Free From WaterReproduction Free From Water Seed coatSeed coat - surrounds & protects the embryo & - surrounds & protects the embryo &

keeps the contents of the seed from drying outkeeps the contents of the seed from drying out

Gymnosperms - Cone BearersGymnosperms - Cone Bearers Gymnosperms include: gnetophytes, cycads, Gymnosperms include: gnetophytes, cycads,

ginkgoes, & conifersginkgoes, & conifers Gnetophytes only have 2 huge leathery leaves, Gnetophytes only have 2 huge leathery leaves,

which grow continuously & spread across the which grow continuously & spread across the groundground

Gymnosperms - Cone BearersGymnosperms - Cone Bearers Cycads are palm-like plants that reproduce Cycads are palm-like plants that reproduce

with large cones, typically found in tropical with large cones, typically found in tropical placesplaces

Gymnosperms - Cone BearersGymnosperms - Cone Bearers Ginkgo may be one of the oldest seed plant Ginkgo may be one of the oldest seed plant

species alive todayspecies alive today Often planted around temples in ChinaOften planted around temples in China Today, they are planted in urban areas where Today, they are planted in urban areas where

their toughness & their toughness & resistance to air pollution resistance to air pollution make them popular shade make them popular shade treestrees

Gymnosperms - Cone BearersGymnosperms - Cone Bearers Some conifers like the Some conifers like the

bristlecone pine tree can live bristlecone pine tree can live for more than 400 yearsfor more than 400 years

Others like the giant redwoods, Others like the giant redwoods, can can grow to more than 100m grow to more than 100m in in heightheight

Gymnosperms - Cone BearersGymnosperms - Cone Bearers Today, conifers thrive in a wide variety of Today, conifers thrive in a wide variety of

habitats in several biomeshabitats in several biomes Most conifers are “evergreens” - they keep Most conifers are “evergreens” - they keep

their leaves throughout the yeartheir leaves throughout the year

Angiosperms - Flowering PlantsAngiosperms - Flowering Plants Angiosperms develop unique reproductive Angiosperms develop unique reproductive

organs known as flowersorgans known as flowers Flowers contain ovaries, which surround & Flowers contain ovaries, which surround &

protect the seedsprotect the seeds FruitFruit - a wall of tissue surrounding the seed - a wall of tissue surrounding the seed

Diversity of AngiospermsDiversity of Angiosperms Monocots & dicots are the 2 classes of Monocots & dicots are the 2 classes of

angiospermsangiosperms They are named for the # of seed leaves, or They are named for the # of seed leaves, or

cotyledons, in the plant embryocotyledons, in the plant embryo MonocotsMonocots - 1 seed leaf - 1 seed leaf DicotsDicots - 2 seed leaves - 2 seed leaves CotyledonCotyledon - the first leaf or first pair of leaves - the first leaf or first pair of leaves

produced by the embryo of a seed plantproduced by the embryo of a seed plant

Characteristics of Monocots & Characteristics of Monocots & DicotsDicots

Diversity of AngiospermsDiversity of Angiosperms There are 3 categories of plant life spans: There are 3 categories of plant life spans:

annual, biennial, & perennialannual, biennial, & perennial AnnualsAnnuals - flowering plants that complete a life - flowering plants that complete a life

cycle within one growing seasoncycle within one growing season

Diversity of AngiospermsDiversity of Angiosperms BiennialsBiennials - angiosperms that complete their - angiosperms that complete their

life cycle in 2 yearslife cycle in 2 years PerennialsPerennials - flowering plants that live for more - flowering plants that live for more

than 2 yearsthan 2 years