CHAPTER 25CHAPTER 25

PLANTSPLANTS

PLANTS PLANTS Most are autotrophic organismsMost are autotrophic organisms

Provide food for themselves and the Provide food for themselves and the worldworld

Have chlorophyll for Have chlorophyll for photosynthesisphotosynthesis

Found in most environmentsFound in most environments oceans, fresh water, polar regions, oceans, fresh water, polar regions,

land, and desert conditionsland, and desert conditions

PLANTSPLANTS 3 Common characteristics:3 Common characteristics:

Anchored to soil, rock, bark, and other solid Anchored to soil, rock, bark, and other solid objectsobjects

Have hard, woody tissue for support to allow Have hard, woody tissue for support to allow them to stand uprightthem to stand upright

Have chlorophyll (green) and are able to Have chlorophyll (green) and are able to photosynthesizephotosynthesize

Botany - The branch of biology that studies Botany - The branch of biology that studies plantsplants

ALTERNATION OF ALTERNATION OF GENERATIONSGENERATIONS

Live alternatively between two different Live alternatively between two different forms during their life cycle.forms during their life cycle.

One stage is diploid (2n) – sporophyteOne stage is diploid (2n) – sporophyte The other stage is haploid (n) – gametophyteThe other stage is haploid (n) – gametophyte

During sporophyte stage, cells undergo During sporophyte stage, cells undergo meiosismeiosis to produce spores (haploid) to produce spores (haploid)

Spores then germinate into the Spores then germinate into the gametophyte (haploid) through gametophyte (haploid) through mitosismitosis

Produces the male and female gametesProduces the male and female gametes Gametes fuse to form zygotes (diploid)Gametes fuse to form zygotes (diploid)

Mitosis produces the sporophyte (diploid)Mitosis produces the sporophyte (diploid)

ALTERNATION OF ALTERNATION OF GENERATIONSGENERATIONS

PLANTSPLANTS

Four major groups:Four major groups: Bryophytes – mossesBryophytes – mosses Seedless vascular – horsetails, fernsSeedless vascular – horsetails, ferns Gymnosperms – evergreens, ginkgosGymnosperms – evergreens, ginkgos Angiosperms – flowering plantsAngiosperms – flowering plants

BRYOPHYTESBRYOPHYTES Small, slow growing Small, slow growing

plantsplants Produce motile spermProduce motile sperm Nonvascular (no roots, Nonvascular (no roots,

stems or leaves)stems or leaves) Obtain nutrients from Obtain nutrients from

where they grow or where they grow or from rainfrom rain

Three typesThree types:: mossesmosses liverwortsliverworts hornwortshornworts

BRYOPHYTESBRYOPHYTES Mosses grow as a carpet and have Mosses grow as a carpet and have

leaf-like structures for leaf-like structures for photosynthesisphotosynthesis

Liverworts and hornworts are Liverworts and hornworts are small, low growing plants small, low growing plants composed of a green ribbon of composed of a green ribbon of cells.cells.

Gametophyte generation is most Gametophyte generation is most dominantdominant

ADAPTATIONS TO LAND: ADAPTATIONS TO LAND: VASCULAR TISSUEVASCULAR TISSUE

Designed to move Designed to move water and nutrients water and nutrients within plantswithin plants

Found in roots, stems, Found in roots, stems, and leavesand leaves

Two kinds:Two kinds: XylemXylem—transports—transports

water from rootswater from roots PhloemPhloem—transports —transports

nutrients (food) from nutrients (food) from leavesleaves

ROOTSROOTS

May be fibrous or tap May be fibrous or tap rootsroots

Also used to store Also used to store foodfood

carrots, turnips, carrots, turnips, radishesradishes

Have root hairs that Have root hairs that increase the surface increase the surface area for absorption of area for absorption of nutrients.nutrients.

STEMSSTEMS

Most are above groundMost are above ground Many have buds which may grow to Many have buds which may grow to

be leaves, flowers, or new branchesbe leaves, flowers, or new branches Function of stems:Function of stems:

support leavessupport leaves Transport materials from roots to Transport materials from roots to

leavesleaves Transport food from leaves to rootsTransport food from leaves to roots

LEAVESLEAVES

The sites of photosynthesisThe sites of photosynthesis Characterized by:Characterized by:

Cells have chloroplastsCells have chloroplasts Have a waxy coating (cuticle) to help Have a waxy coating (cuticle) to help

avoid water lossavoid water loss Have vascular tissue Have vascular tissue Openings known as Openings known as stomatastomata control control

movement of CO2, oxygen, and watermovement of CO2, oxygen, and water

LEAVESLEAVES

SEEDLESS VASCULARSEEDLESS VASCULAR Includes ferns, Includes ferns,

horsetails, and club horsetails, and club mossesmosses

Produce diploid and Produce diploid and haploid sporeshaploid spores

Fertilization results in Fertilization results in multi-cellular embryomulti-cellular embryo

Sporophyte generation Sporophyte generation is more dominantis more dominant

Have well developed Have well developed vascular tissuevascular tissue

GYMNOSPERMSGYMNOSPERMS Seed-producing Seed-producing

plantsplants A seed contains:A seed contains:

An embryo An embryo Protective seed coatProtective seed coat Stored food for the Stored food for the

embryoembryo Produce cones for Produce cones for

reproduction (both reproduction (both male and female)male and female)

Includes evergreens Includes evergreens and ginkgosand ginkgos

GYMNOSPERMSGYMNOSPERMS Technically means “naked seeds”Technically means “naked seeds”

Vulnerable to environmental conditionsVulnerable to environmental conditions Many have needle-shaped leaves Many have needle-shaped leaves

that fall periodically throughout the that fall periodically throughout the year (not all at the same time)year (not all at the same time)

Known as perennials – get taller and Known as perennials – get taller and larger year after yearlarger year after year

ANGIOSPERMSANGIOSPERMS

Seeds are protected Seeds are protected by the ovaryby the ovary

matures into a fruitmatures into a fruit Many foods we eat Many foods we eat

are fruits containing are fruits containing seeds of seeds of angiosperms: angiosperms:

green beans, melons, green beans, melons, tomatoes, and applestomatoes, and apples

ANGIOSPERMSANGIOSPERMS Most have broad Most have broad

leaves which they leaves which they may lose during the may lose during the fall (cooler regions)fall (cooler regions)

Deciduous treesDeciduous trees Some keep their Some keep their

leaves all winterleaves all winter American holly American holly Ilex Ilex

opacaopaca Most are small Most are small

plants, grasses, plants, grasses, wildflowers, and wildflowers, and house plantshouse plants

ANGIOSPERMSANGIOSPERMS Flower produce gametesFlower produce gametes

Pistil – female reproductive organsPistil – female reproductive organs Style, stigma, ovaryStyle, stigma, ovary

Stamen – male reproductive organsStamen – male reproductive organs Anthers, filamentsAnthers, filaments

Sepals – outermost protective structuresSepals – outermost protective structures Petals – accessory organs for fertilizationPetals – accessory organs for fertilization

If a flower has both male and female If a flower has both male and female parts, it is called a perfect flower.parts, it is called a perfect flower.

If just one part – imperfect flowerIf just one part – imperfect flower Flowers are used to attract insects for Flowers are used to attract insects for

pollination. pollination.

PERFECT FLOWERPERFECT FLOWER

ANGIOSPERMSANGIOSPERMS Divided into two categories: Divided into two categories:

Monocots and dicotsMonocots and dicots Monocots have:Monocots have:

One-part seed (monocotyledon) – cornOne-part seed (monocotyledon) – corn Parallel veins on leavesParallel veins on leaves Vascular tissue arranged in scattered Vascular tissue arranged in scattered

bundlesbundles Dicots have:Dicots have:

Two-part seed (dicotyledons) – beansTwo-part seed (dicotyledons) – beans Net-like vein pattern on leavesNet-like vein pattern on leaves Vascular tissue arranged in ringsVascular tissue arranged in rings

DICOTS AND MONOCOTSDICOTS AND MONOCOTS

TROPISMTROPISM Reaction of a plant to a stimulusReaction of a plant to a stimulus

LightLight WaterWater

Plants release a hormone (auxin) in Plants release a hormone (auxin) in response to the direction of a light sourceresponse to the direction of a light source

PhototropismPhototropism Some hormones also control changes in Some hormones also control changes in

their growth and developmenttheir growth and development Based on day lengthBased on day length Some produce flowers only on long days, Some produce flowers only on long days,

others on short daysothers on short days

CHAPTER 25CHAPTER 25

PLANTSPLANTS