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Kingdom Plantae

Plant Evolution: Aquatic Ancestor

•Group of green algae is the closest living species to a possible land plant ancestor

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Algae & Land Plant Similarities

•Both contain chlorophylls a and b •Have chloroplasts •Store starch •Cellulose in cell walls

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Terrestrial Habitat

Aquatic Habitat

Plant Adaptations to Land Problems:

1. Need minerals 2. Gravity 3. Increase in

Height for Light

4. Adaptations for Drier environment

5. Reproduction

Solutions: 1. Roots absorb H2O &

minerals 2. Cellulose in cell walls

are rigid 3. Vascular Transport

System 4. Waxy cuticle &

stomata with guard cells

5. Pollen containing sperm

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Common Characteristics of Plants

•Multicellular •Autotrophic (photosynthesis) •Surrounded by cell walls containing cellulose •Stores reserve food (starch)

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General Reproduction in Plants

•Alternation of generations life cycle •Diploid (2n) sporophyte stage •Haploid (1n) gametophyte stage •Produce multicellular embryo

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2n Sporophyte

1n gametophyte

1n pollen

Ovary with 1n ovules (eggs)

2n seed with plant embryo

Sporophyte

Gametophyte

Taxonomy • Plants are divided into two groups

• Based on the presence or absence of an internal transport system known as the Vascular System

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Vascular Bundles

Vascular System

•Xylem tissue carries water and minerals upward from the roots •Phloem tissue carries sugars made by photosynthesis from the leaves to where they will be stored or used

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Nonvascular Plants

• Do not have vascular tissue for support or conduction of materials

• Called Bryophytes

• Require a constantly moist environment

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Sporophyte stage

Gametophyte Stage

Nonvascular Plants

•Plants can’t grow tall •Cells must be in direct contact with moisture •Materials move by osmosis cell-to-cell •Sperm must swim to egg through water droplets

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Nonvascular Plants examples

•mosses

• liverworts

•hornworts

13 Liverworts Hornworts

Moss

Main Parts of Vascular Plants

• Shoots -Attach leaves -Photosynthetic

part of plant • Roots

-Absorb water & minerals

-Anchors the plant

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Vascular Plants

Subdivided into two groups –1.Seedless vascular plants 2.Seed-bearing vascular plants

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Vascular Plant Taxonomy

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Seedless Vascular Plants • club moss

• horsetails

• whisk ferns

• ferns

17 Horsetails Whisk ferns

Ferns

Seed-Producing Vascular Plants •Includes two groups – Gymnosperms and Angiosperms •Gymnosperms have naked seeds in cones •Angiosperms have flowers that produce seeds to attract pollinators and produce seeds

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Seed-Producing Vascular Plants Groups

• Gymnosperm –cone bearing or “naked seed”

• Angiosperm-flowering plants

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Gymnosperms

•Examples: pine, cedar, spruce, and fir

•Cycads, ginkgo

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Ginkgo

Cycad

Pine

Gymnosperms •Contains the oldest living plant – Bristle cone pine

•Contains the tallest living plant – Sequoia or redwood

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Angiosperms

• Flowering plants (not all flowers can be seen!) • ~200,000 species; makes up 80% of all plant species on Earth

• Seeds are formed when an egg or ovule is fertilized by pollen in the ovary

• Requires pollination

• Self-pollination, wind pollination, animal influence pollination (35%)

• Fruits are frequently produced from the ripened ovaries of the flower…you might not be able to see all fruit!

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Angiosperms

•Division Anthophyta •Subdivided into two classes – Monocots and Dicots •Monocots have a single seed cotyledon •Dicots have two seed cotyledons

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Monocots

•Parallel venation in leaves •Flower parts in multiples of 3 •Vascular tissue scattered in cross section of stem

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Dicots

•Net venation in leaves •Flower parts in multiples of 4 or 5 •Vascular tissue in rings in cross section of stem

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Monocots Monocots

Dicots Dicots

How can you tell the difference?

Plant Kingdom

Non Vascular

seedless

Club moss

angiosperm

Douglas fir

monocot

Liverworts

moss

Flowers are in ______

_____ veins in leaves

______ veins in leaves

Flowers are in_____

Stop

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Seed Plant Structure

•The three principal organs of seed plants are roots, stems, and leaves. •These organs perform functions such as the transport of nutrients, protection, and make food.

Seed Plant Structure

Function of Roots:

•absorb water and

dissolved nutrients.

•anchor plants in

the ground.

Seed Plant Structure Stems provide:

•a support system for

the plant body.

•a transport system

that carries nutrients.

Seed Plant Structure Function of Leaves: •A plant’s main photosynthetic system.

Vascular Tissue

•Vascular tissue forms a transport system that moves water and nutrients throughout the plant. •Vascular tissue is made up of xylem, a water-conducting tissue, and phloem, a food-conducting tissue.

Meristematic Tissue •New cells are produced at the tips of the roots and stems.

This is the meristem tissue that is responsible for continuing growth throughout a plant's lifetime.

Types of Roots

• In some plants, the primary root grows long and thick. This primary root is called a taproot.

• A carrot is an example of a taproot.

Types of Roots

•Fibrous roots branch so that no single root grows larger than the rest.

•Fibrous roots are found in grasses.

Root Structure and Growth •The root’s surface is covered with root hairs. Root hairs increase the surface area for water to enter the plant.

Root

hairs

Root Structure and Growth

•The epidermis protects the root and also absorbs water.

Epidermis

Root Structure and Growth

•Inside the epidermis is a layer of ground tissue (cortex)

Ground

tissue

(cortex)

Root Structure and Growth

•The cortex extends to another layer of cells, the endodermis.

•The endodermis completely encloses the vascular cylinder.

Endodermis

Root Structure and Growth •The vascular cylinder is the central region of a root that includes the xylem and phloem.

Vascular cylinder

Phloem

Xylem

Root Functions

•Osmosis and active transport move water and minerals from the root epidermis into the cortex.

Stems

Stem Structure and Function

•Stems have three important functions: 1. they produce leaves,

branches and flowers 2. they hold leaves up to the

sunlight 3. they transport substances

between roots and leaves

•All seed plants undergo primary growth, which is an increase in length. •For the entire life of the plant, new cells are produced at the tips of roots and shoots. Year 1 Year 2 Year 3

Primary

growth

Apical meristem

Primary

growth

Leaf

scar

Secondary Growth of Stems

•Vascular cambium increases the thickness of stems over time.

•Cork cambium produces the outer covering of stems (AKA: bark) which also increases the thickness of the stem.

Secondary Growth of Stems

• The vascular cambium appears as a thin layer • xylem cells

move toward the center

• phloem cells move toward the outside and becomes part of the bark.

Leaves

Leaf Structure

•The structure of a leaf is optimized for absorbing light and carrying out photosynthesis. •6CO2 + 6H2O C6H12O6 + 602

Review Photosynthesis and Respiration

•How does the plant get the CO2? •How does the plant get the water? •Where does the glucose molecules go? •Where does the O2 molecules go?

Leaf Structure •Leaves are covered on the top and bottom by epidermis which is used for protection.

Upper

Epidermis

Lower

Epidermis

Leaf Structure •The epidermis of many leaves is covered by the cuticle which prevents drying out.

Cuticle

Leaf Structure

The

veins

of

a

leaf Xylem

Phloem Vein

Leaf Functions • Palisade mesophyll are closely-packed cells absorb light that enters the leaf.

Palisade

mesophyll

Leaf Functions • Spongy mesophyll is loose tissue with many air spaces between its cells. It traps light for photosynthesis.

Spongy

mesophyll

Leaf Functions

• Stomata are porelike openings in the underside of the leaf that allow carbon dioxide and oxygen to diffuse into and out of the leaf.

Stoma

Leaf Functions • Each stoma consists of two guard cells.

• Guard cells control the opening and closing of stomata by responding to changes in water pressure.

Guard cells

Leaf Functions

• Transpiration is the loss of water through its leaves. This lost water is replaced by water drawn into the leaf through xylem vessels in the vascular tissue.

Leaf Functions Plant leaves allow gas exchange between air spaces in the spongy mesophyll and the exterior by

opening their stomata.

Leaf Functions • Guard cells are specialized cells that control the stomata.

• Stomata open and close in response to changes in water pressure within guard cells.

Leaf Functions • When water pressure within guard cells is high, the stoma open.

Leaf Functions • When water pressure within guard cells decreases, the stoma closes.

Stop

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Flower and Seed Plants

Gymnosperms & Angiosperms

Gymnosperm

• Gymno means “naked”; sperm means “seed”

• Cone-bearing plants

• Pines, Cedars, firs….coniferous Plants

• Sporophyte and gametophyte life stages

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Gymnosperm Life Cycle

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ANGIOSPERMS

•Angiosperm means “covered seed”

•Have flowers

• Live everywhere – dominant plants in the world

•Angiosperms are the most successful and advanced plants on earth

Angiosperm Plant Reproduction

•Asexual Reproduction- •No partner

•Sexual Reproduction- •Cross fertilization

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Asexual reproduction • Plant can reproduce

asexually by: • Breaking plant parts off

• Roots (Runners, stolons, suckers, etc.)

• Bulbs

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Angiosperm Sexual Reproduction • Fertilization is the process of the female and male gametes

combining

• Cross fertilization • 2 separate plants with both sets of reproductive parts or only one set

• Self-Fertilization • Single plant with both male and female reproductive parts

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Life Cycle Of an Angiosperm

What is the reproductive structure ? Flowers!

Flower Anatomy

MALE = stamen

Anther filament

FEMALE = Carpal or pistil

Stigma style ovary

Flower Anatomy

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Flower structure • Male sex organs: Stamen: composed of anther –

organ that produces pollen.

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Flower structure

• Female sex organs: The carpel The Ovary is the enlarged base that contains the ovules

The stigma is

the sticky end

of the carpel

for the pollen

grains to

adhere

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Flower structure

• Sepals (green) are the outermost whorl of leaf it protects the flower.

• Petals (usually colored) are the inner whorl of leaf it attracts a pollinator.

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Angiosperm Reproduction

Angiosperm Reproduction

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Types of flowers or inflorescence A flower is….

• Complete = has both female AND male reproductive parts

• Incomplete = has only female OR male reproductive parts

• Perfect = has both female AND male reproductive parts

• Imperfect = has only female OR male reproductive parts

• Pistillate flower is a flower with only female parts.

• Staminate flower is a flower with only male parts.

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* Pollination = Pollen falls on a stigma

when wind, bees, or bats carry it. * Fertilization = sperm (pollen grain) & egg (ovule) join together in the flower’s ovary. - The zygote develops into the embryo part of the seed. - The ovary around the seed develops into a fruit.

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Seeds • Cotyledon is stored food tissue – for the embryo to

grow

• Mature ovule becomes the seed coat and/or fruit

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Seeds

• Seeds contain a young, developing plant embryo

• Seeds are covered with a protective seed coat Seeds form from ripened ovules after fertilization

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Seed Structure Examples:

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Seed Dispersal • Seeds must be scattered

(dispersed) away from the parent plant

• Testa (seed coats) may last thousands of years

• Seeds eaten by animals aren’t digested but pass out with wastes

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Seed Dispersal

• Seeds may have adaptations such as stickers, hooks, or fuzz to adhere to animals

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Seed Dispersal

•Both water and wind can scatter seeds

Wind Dispersal

Water Dispersal

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Fruits • Fruits form when ovary with ovules ripen

• May be dry and hardened (nuts)

• May be enlarged and fleshy (berries, apples, tomatoes)

• Used to help disperse seeds

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Types of Fruits

•Simple fruits – form from a single ovary (apple)

•Aggregate fruits – forms from several ovaries of the same flower (blackberry)

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Tropism = a plant’s growth response toward or away from a stimulus. •Stimuli can be light, touch, and gravity. •Touch (thigmotropism): vines coil around anything they touch.

Geotropism or Gravitropism

• Gravity • roots grow toward soil

and stems grow away from gravitational pull

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• Light (phototropism):

leaves, stems, grow toward light.

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Hormones = a chemical that affects how

the plant grows and develops, and make tropism possible. * Hormones also control germination, formation of flowers, stems, and the shedding of leaves and ripening of fruit.

Hormones

• Gibberellins: stimulates the growth and the development of fruits and seeds. • Cytokinins: Stimulates the growth of cells

• Ethylene: a gas released from fruit that promotes

ripening.

Hormones

• Auxin stimulates cell elongation in a rapidly growing region near the tip of the plants root or stem.

• If light shines on one side of a stem, auxin moves to the shaded side and causes that side to grow faster so the stem bends

toward the light as it grows.

Plant Responses to Environmental Stimuli • a decrease in water pressure (or Turgor Pressure)

in plant cells causes wilting.

• Turgor Pressure is the water pressure in the large central vacuole pushing up against the cell wall. • Decreased turgor pressure = wilting

• Stable turgor pressure = stable plant or turgid

• Increased or excessive turgor pressure = cell breakage (doesn’t happen often due to osmosis and diffusion across the cell membrane!)

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