PlantsPlants

What makes a plant a What makes a plant a plant?plant?

• has a cell wall• has chloroplast & chlorophyll• produce its own food• kisnot mobile

Plant Cell Animal Cell

Vs.

So where did plants come from?

?

Plant Evolution

Early LifeEarly Life• Plants evolved from algae and

lived in the water

• The first plant appeared about 400 million years ago!

Bryophytes Bryophytes • Next, plants moved to land. The first

plants were small and lived close to the water because they had to absorb water from their environment.

• These plants are called Bryophytes (or

non-vascular plants).

Vascular plantsVascular plants

• When plants developed tube-like structures that could transport water, plants were able to live away from the water’s edge.

• These plants are called vascular plants.

What is a vascular system?What is a vascular system?

• Specialized tissue that transports water and nutrients throughout a plant.

Cross section

of a stem

Characteristics:*must live where it’s damp, moist or wet

* water moves through cell walls

* no roots, stem or leaves

* sperm move through water

Nonvascular Plants (Bryophytes)

*Rhizoids - root-like

MossesMosses

Hornwort & Hornwort & LiverwortsLiverworts

* “wort” = English for plant

Liverworts & Liverworts & HornwortsHornworts

Characteristics:

* can live away from water* transport water & materials through plant* supports their bodies* has true roots, stems and leaves

Types:1. Ferns2. Horsetails3. Club Mosses

4. Gymnosperms

5. Angiosperms

ReproducesWithoutseeds

ReproducesWith seeds

Vascular Plants

FernsFerns• 400 million years old!

• Vascular tissue.

• Spores - needs moist environment.

• Stems grow underground.

• Leaves called fronds.

Club MossClub Moss

Club MossClub Moss• Also called Ground

Pine or Princess Pine

• Needle-like leaves

• Club Moss are NOT mosses!!

HorsetailsHorsetails

• Few species today ( ONLY 30!)

• Jointed stems with branches in a circle around each joint.

• Called “Scouring rushes” in Colonial times.

GymnosperGymnospermsms

• Oldest type of seed plant

• Naked seed (not enclosed)

• Needle like or scale like leaves

• Deep growing root systems

• Cones (male & female)

AngiospermsAngiosperms• Flowering Plants

• Seeds within a covering

• Flowers may have both male and female organs.

• Two groups: monocots and dicots.

• Angiosperms are classified into two groups based on the number of seed cotyledons (kaht uh leed uhns).

• Cotyledons are the leaf-like parts of the plant embryo inside the seed.

Monocots• A monocot has only one cotyledon.

• There are other features typical to monocots– Leaves are narrow with parallel veins– Roots are fibrous– Flower parts are in multiples of three– Stem vascular tissues are in bundles.

• Examples of monocots:-Corn, grasses, tulips, lilies

Fun fact: Palm trees are the only monocot trees!

Dicots• A dicot seed has two cotyledon

• There are other features typical to dicots:– Leaves have branching pattern of veins– Dicots have a large, thick taproot- (makes it hard to uproot)– Flower parts are in multiples of four or five. – Stem vascular tissues are arranged in a ring.

• There are about four times more dicot species than there are monocot species.

• Examples of dicots:– All broad-leafed trees, fruit trees, tomatoes, potatoes, peas,

squash, lettuce, sunflowers, roses, violets.

Cross Section of a Leaf…(if you were to cut a leaf and look at it from the side, you’d get this…)

Cuticle (Waterproof coating)

• prevents excess water loss• shiny

Epidermis• light can pass through.• protection

Mesophyll“meso” means middle “phyll” means

leaf

Palisade mesophyll

• Most photosynthesis happens here

Spongy mesophyll• Photosynthesis occurs here too

• Air spaces allow carbon dioxide, oxygen and water vapor to flow freely

Stomata• “stoma” means mouth• Opening allows carbon dioxide to enter

and oxygen and water to leaves• Guard cells - controls opening

• Made of two slightly curved epidermal

cells

• Open during day , closed at night.

100% 75% 50%

25% 15% 0%

Stomata Openings

Xylem• carries water and minerals from

roots up through plants• helps support plant because to thick

walls.

Phloem• carries food throughout plant, both

upward and downward.

Stem StructureStem Structure• Herbaceous - soft

and flexible stems (ex: grass, corn)

• Woody - hard and stiff stems (ex: trees, shrubs)

– Wood - old water-carrying cells (xylem) vascular tissue

– Bark - old growth

– Cambium - produces new xylem and phloem

Stem FunctionStem Function

• Support• holds up leaves so they are exposed

to the sun• carries substances between the

plant’s roots and leaves• stores glucose

Root Structure Root Structure

• root cap - pushes through soil• root hairs - increases surface area

exposed to soil• epidermis - protection

Root FunctionRoot Function

• supports and anchors• absorbs water and nutrients from the

soil• stores glucose in the form of starch

Types of rootsTypes of roots

Taproot Fibrous

Plant Reproduction

Types of Plant Reproduction1. Asexual Reproduction- does not require the

production of sex cells (no sperm or eggs); new plant is genetically the same as the parent. Ex: potatoes, spider plants, strawberry plants, root,

leaf or stem cuttings.

2. Sexual Reproduction- requires the production of sex cells (needs sperm or eggs); new plants are genetically different from the parents.

Fertilization- sperm and egg combine to form a new organism (called a zygote)

Plant Life Cycles

• Two Stages:– Gametophyte- gamete- forming platns (sperm or

egg called sex cells) – haploid cells

– Sporophyte- spore-forming platns; diploid cells.

Flowers

Function• Reproduction.• Pollination-

1. Pollen falls on stigma.2. Pollen Tube is produced that allows sperm cells to move

down to the ovary to join egg cells3. Egg cell join with sperm cell (fertilization).4. Ovule develops into a seed5. The ovary develops into a fruit that encloses the seed.

The fruit helps in seed dispersal.

Structure • Sepals - often green leaf-like; protects developing flower

• Petals - colorful leaf-like structure; attracts insects & other animals

• Pistil - found in center of flower; female reproductive part made up of:– stigma - sticky tip of pistil; pollen is deposited here– style - slender tube; connects the stigma to a hollow structure at

the base of the flower.– Ovary- bottom of the pistil; contains eggs to be fertilized.

• Stamen - male reproductive parts that is made up of:– filament - stem-like ; holds up anther– anther knobs at end of stalk; pollen is produced here.

Types of flowers• Imperfect Flower: has either male OR

female reproductive parts, but NOT both.

• Perfect Flower: has both male and female parts.

How does a plant get it’s energy?

Photosynthesis!•“photo” means light, “synthesis” means to put together

•process in which food is synthesized using light energy

•occurs in Chlorophyll (a green pigment)

•Food made is a sugar called glucose

6 CO2 + 6 H2O C6H12O6 + 6 O2Sunlightchlorophyll

Carbon water glucose oxygen dioxide

Respiration•release of stored energy in glucose

C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

Glucose oxygen carbon waterdioxide