Plantae 2Plantae 2

Botany –the study of plantsBotany –the study of plants

This unit primarily a study of AngiospermsThis unit primarily a study of Angiosperms

- Plant parts and tissues (roots, stems and leaves)- Plant parts and tissues (roots, stems and leaves)

- Flowering Plant Reproduction- Flowering Plant Reproduction

Meristematic TissueMeristematic Tissue

Unlike animals, plants only Unlike animals, plants only

divide in specific areas called divide in specific areas called meristemsmeristems

Meristems found at the Meristems found at the

tips of roots and stems tips of roots and stems

are called are called apical meristemsapical meristems

and produce the most rapid growthand produce the most rapid growth

Root and stem Root and stem lengtheninglengthening is is called called primary growth primary growth

More Meristematic TissueMore Meristematic Tissue

Cork cambium Cork cambium produces the outer covering of produces the outer covering of stemsstems

Vascular cambium Vascular cambium produces vascular tissue produces vascular tissue and increases the thickness of stems over time.and increases the thickness of stems over time.

Pericycle Pericycle enables roots to grow thicker and enables roots to grow thicker and makes it possible for roots to branchmakes it possible for roots to branch

Secondary growth Secondary growth is the increase in diameteris the increase in diameter Most herbaceous monocots don’t experience Most herbaceous monocots don’t experience

secondary growth while all woody plants dosecondary growth while all woody plants do

Plant Tissue TypesPlant Tissue Types Plant cells differentiate into Plant cells differentiate into

three kinds of tissue : three kinds of tissue : epidermal, vascular and epidermal, vascular and groundground

There are also three main types of There are also three main types of cells used to make these tissuescells used to make these tissues

ParenchymaParenchyma is the thin walled cell is the thin walled cell found throughout a plantfound throughout a plant

Sclerenchyma Sclerenchyma cells have tough thick cells have tough thick walls and are used to strengthen and walls and are used to strengthen and support plant tissuessupport plant tissues

CollenchymaCollenchyma is mainly a is mainly a developmental support cell and we developmental support cell and we won’t address it in this unitwon’t address it in this unit

Epidermal tissueEpidermal tissue

Epidermal tissue, Epidermal tissue, like the skin on us, like the skin on us, protects plants protects plants from parasites from parasites and from water and from water loss, except in the loss, except in the roots were it roots were it facilitates water facilitates water entry.entry.

Tightly packed epidermal cells

Vascular TissueVascular Tissue

Vascular tissues Vascular tissues include xylem and include xylem and phloemphloem

Xylem consists of Xylem consists of tracheids and vessel tracheids and vessel elements (usually dead elements (usually dead when mature)when mature)

Phloem cells are Phloem cells are called sieve tube called sieve tube members ( alive when members ( alive when mature, no nucleus)mature, no nucleus)

Ground tissueGround tissue

Ground tissue is usually Ground tissue is usually made up of parenchyma.made up of parenchyma.

When found at the When found at the center of roots and center of roots and stems it’s called pith. stems it’s called pith.

Important functions of Important functions of ground tissue is to ground tissue is to support vascular tissue support vascular tissue and store food and and store food and water.water.

CS of stem

Roots, Stems and LeavesRoots, Stems and Leaves

Sun EnergySun Energy

6CO6CO22 + H + H22O CO C66HH1212OO6 6 + 6O+ 6O22

Every developmental adaptation of roots, stems and leaves is Every developmental adaptation of roots, stems and leaves is

a slave to this formula. a slave to this formula.

Roots gather water, stems hold up leaves to the sun that have Roots gather water, stems hold up leaves to the sun that have

adapted to take in carbon dioxide to produce the energy adapted to take in carbon dioxide to produce the energy

the rest of us need to live.the rest of us need to live.

Roots Roots

Anchor the plantAnchor the plant Absorb water and minerals Absorb water and minerals

from the soilfrom the soil Store food that is produced Store food that is produced

in the leavesin the leaves Two types : fibrous and Two types : fibrous and

taproottaproot

RootsRoots

Roots are Roots are composed of composed of three structures :three structures :

epidermis, epidermis, cortex and cortex and vascular cylindervascular cylinder

RootsRoots

The epidermis contains The epidermis contains root hairs which greatly root hairs which greatly increase the surface area increase the surface area of the root system and of the root system and increase the plants increase the plants capacity to absorb watercapacity to absorb water

RootsRoots The cortex is mostly parenchyma with an inside layer The cortex is mostly parenchyma with an inside layer

of endodermis that controls water flow into the of endodermis that controls water flow into the vascular cylinder using active transport of mineralsvascular cylinder using active transport of minerals

Vascular CylinderVascular Cylinder

Monocots and Dicot roots have different vascular Monocots and Dicot roots have different vascular cylinderscylinders

MONOCOT DICOT

StemsStems

Stems transport food, Stems transport food, water, and minerals water, and minerals between the roots and between the roots and leaves and support leaves and support plant growth above plant growth above ground, exposing ground, exposing leaves to the sun.leaves to the sun.

Stems have four types of Stems have four types of tissue : Parenchyma (pith), tissue : Parenchyma (pith), vascular, cambium (vascular vascular, cambium (vascular and cork), and cork tissue and cork), and cork tissue (bark)(bark)

The arrangement of vascular The arrangement of vascular tissue differs between tissue differs between monocots and dicotsmonocots and dicots

Herbaceous stems- with Herbaceous stems- with little or no secondary little or no secondary growth these stems are growth these stems are partially supported by partially supported by turgor pressure, the turgor pressure, the pressure of water in the pressure of water in the vacuoles.vacuoles.

Woody stems exhibit Woody stems exhibit secondary growth secondary growth adding another ring of adding another ring of xylem each yearxylem each year

LeavesLeaves

Leaves are the original Leaves are the original solar collectorssolar collectors

They need sun, water They need sun, water and COand CO2 2 to make our to make our

food and so they food and so they maximize their surface maximize their surface area (thin and flat) to area (thin and flat) to maximize the result.maximize the result.

LeavesLeavesLeaves are made up of epidermis, vascular tissue and Leaves are made up of epidermis, vascular tissue and

ground tissue ( mesophyll) like all plant parts. ground tissue ( mesophyll) like all plant parts.

EpidermisEpidermis The epidermis is The epidermis is

responsible for responsible for balancing the need for balancing the need for water in the leaf with water in the leaf with the need for air, which the need for air, which evaporates the water.evaporates the water.

CutinCutin, a waxy , a waxy substance, is secreted substance, is secreted to slow evaporation to slow evaporation

StomataStomata, openings , openings found on the bottom of found on the bottom of the leaf, control gas the leaf, control gas exchange and water exchange and water loss.loss.

EpidermisEpidermis

Guard cells control the opening of the stomata, Guard cells control the opening of the stomata, closing and opening as needed.closing and opening as needed.

MesophyllMesophyll The The mesophyllmesophyll, or middle part of the leaf ,contains the most important , or middle part of the leaf ,contains the most important

factory on the planet.factory on the planet. The vascular bundle is also found in the mesophyllThe vascular bundle is also found in the mesophyll The mesophyll is made up of two kinds of parenchyma , the The mesophyll is made up of two kinds of parenchyma , the palisade palisade

layerlayer and the and the spongy layer.spongy layer.

Leaves and Water LossLeaves and Water Loss

TranspirationTranspiration is evaporation of water through is evaporation of water through the stomata .the stomata .

Temperature ,humidity and wind speed all Temperature ,humidity and wind speed all affect the rate of transpirationaffect the rate of transpiration

The unique polar characteristics of water The unique polar characteristics of water causes it to exhibit both cohesion and adhesion causes it to exhibit both cohesion and adhesion

This This transpiration pulltranspiration pull allows water to move allows water to move up large trees at the rate of as much as 100 up large trees at the rate of as much as 100 gallons a day with little energy use.gallons a day with little energy use.

Reproduction in Flowering PlantsReproduction in Flowering Plants

Flowers come in a variety of Flowers come in a variety of shapes ,smells ,colors and shapes ,smells ,colors and odors designed to attract odors designed to attract pollinators of all kinds.pollinators of all kinds.

Fertile Flower PartsFertile Flower Parts

Stamens are the male part Stamens are the male part of a flower. They consist of of a flower. They consist of two parts called the two parts called the filament which holds up filament which holds up the anther were pollen is the anther were pollen is produced. produced.

The pistil is the female part The pistil is the female part and is made up of the style, and is made up of the style, stigma and ovary which stigma and ovary which contains the ovules where contains the ovules where the egg cells are produced. the egg cells are produced.

Sterile Flower PartsSterile Flower Parts

The receptacle is the base of The receptacle is the base of the flower. the flower.

The sepals enclose the flower The sepals enclose the flower bud and collectively form the bud and collectively form the calyx which protects the calyx which protects the ovary.ovary.

Petals are the colorful Petals are the colorful fragrant part that protect the fragrant part that protect the pistil and stamens. pistil and stamens. Collectively the petals form Collectively the petals form the corolla.the corolla.

Kinds of FlowersKinds of Flowers

FertilizationFertilization

The tube cell forms the pollen tube , while the The tube cell forms the pollen tube , while the generative cell divides and in a process called generative cell divides and in a process called double fertilizationdouble fertilization forms a zygote and a forms a zygote and a triploid (3N) triploid (3N) endosperm.endosperm.

The endospermThe endosperm normally provides food for the normally provides food for the embryo unless we eat it in the form of corn or embryo unless we eat it in the form of corn or wheat or rice.wheat or rice.

Seeds and FruitSeeds and Fruit

When fertilized the When fertilized the ovule becomes a seedovule becomes a seed

As the seeds mature As the seeds mature inside it the ovary inside it the ovary ripens.ripens.

A ripened ovary is a A ripened ovary is a fruit which contains fruit which contains seeds.seeds.

FruitsFruits

Fruits can be dry (nuts, Fruits can be dry (nuts, burrs or winged) or fleshy burrs or winged) or fleshy

( peaches apples and berries)( peaches apples and berries) Simple fruits form from a Simple fruits form from a

single ovarysingle ovary Aggregate fruits form from Aggregate fruits form from

flowers that have many flowers that have many pistils on the same flower.pistils on the same flower.

Multiple fruits are single Multiple fruits are single fruits that grow so close fruits that grow so close together they form a single together they form a single structure.structure.

Seed Dispersal Seed Dispersal

Fleshy fruits attract Fleshy fruits attract animals and are animals and are dispersed by them dispersed by them

Dry fruits can be food Dry fruits can be food for animals or they can for animals or they can have hooks or claws have hooks or claws that facilitate their that facilitate their dispersaldispersal

Some seeds are Some seeds are dispersed by air or dispersed by air or waterwater

Environmental InfluencesEnvironmental Influences

Many plants are photoperiodic-they respond Many plants are photoperiodic-they respond through pigment called phytochrome to a through pigment called phytochrome to a critical dark period.critical dark period.

A long day plant produces flowers in the A long day plant produces flowers in the summersummer

A short day plant produce flowers in the spring A short day plant produce flowers in the spring and falland fall

Plant HormonesPlant Hormones

Auxins stimulate elongation of cellsAuxins stimulate elongation of cells

Gibberellins stimulate rapid growthGibberellins stimulate rapid growth

Cytokinins stimulate cell divisionCytokinins stimulate cell division

Ethylene (a gas) stimulates fruit ripeningEthylene (a gas) stimulates fruit ripening

Tropisms and Nastic MovementsTropisms and Nastic Movements

Phototropism is the Phototropism is the movement toward or away movement toward or away from lightfrom light

Geotropism is the positive Geotropism is the positive or negative response to or negative response to gravitygravity

Nastic movements are Nastic movements are rapid turgor pressure rapid turgor pressure movements caused by a movements caused by a stimulusstimulus