PLANTSImportance, characteristics, &

leaves (12.1-12.2)

Importance…• Food…mmmm delicious• Construction material• Medicine• Paper• Bio-fuel• Clothing• Instruments• Toys• Wine and beer• Corks • Chemicals• Fibres• Decoration• OXYGEN!!!!

The List goes on and on!!!!

Canada Stats…• Canola crop $2.5 billion• Wheat $1.8 billion• Corn crop $753 million• Potato crop $899 milliion

In 2006……

Economy of entire communities…

• Cork is produced in Portugal and Spain• It is estimated that 16% of all export income comes

from cork and it accounts for 50% of all cork production worldwide

• It is estimated that with the general trend moving away from cork use in wine bottles, Portugal could be faced with economic crisis

• Luckily there are many other uses for cork including building materials

– http://rt.com/news/corks-dying-out-portugal-s-national-disaster/

Amazing Diversity..• After millions of years of evolution and development, an

enormous number of different plant variations have been created.

• Plants have unusual lives as they are immobile, they cannot move independently and are therefore limited to the environment around them

• To cope with their immobility, plants have many adaptations to survive a variety of environmental conditions.

• Ex. the pitcher plant lives in low nitrogen soil and has evolved a unique way of getting its food

Pitcher Plants (Nepenthes)

• Nepenthes is a genus of carnivorous plant

• The colorful rim functions as a lure to insects.

• A syrupy liquid in attracts, and drowns, and digests potential prey.

• Waxy walls prevent escape of insects that have fallen prey

Sensitive Plant (Mimosa pudica)

• Leaflets fold in and droop when they are touched.

• This is caused by a drop of pressure in certain cells, and leads to a very cool effect.

• The leaves also react to heat and light which causes the plant to fold up every evening.

• http://www.youtube.com/watch?v=Zq3UuHlPLQU

Venus Flytrap (Dionaea muscipula)

• most well-known carnivorous plant• There are small trigger hairs on the leaves which causes

them to fold together when they are touched. The leaves close in less than a second, and the teeth-like spikes on the edge keep larger insects from escaping.

• http://www.youtube.com/watch?v=9sggQQuBU40

Resurrection Fern (Polypodium polypodioides)• incredible ability to withstand drought.• During dry spells, the plant curls up into a ball, turns

brown, and appears to be dead. If it comes in contact with water, it uncurls and comes back to life

• It has been estimated that it can survive for 100 years without water.

• http://www.youtube.com/watch?v=jdB_pmzhhbE

Rafflesia arnoldii• Found in Sumatra• considered to be the

largest flower in the world. • It can grow to be up to

one meter in diameter, and weigh as much as 25 lbs.

• Despite its size, it is incredibly difficult to find because it takes 9-21 months for plant to develop, and the flower lasts for a maximum of five days.

• http://www.youtube.com/watch?feature=endscreen&v=ZgHhDsJSXOI&NR=1

Basic Needs• Energy Photosynthesis, heterotrophs• Nutrients• Water• Gas exchange• Protection from herbivores and disease• Reproduction

Photosynthesis

Getting Energy…• Photosynthesis uses solar radiation, carbon dioxide and

water and converts it to chemical energy to make glucose and oxygen

• Glucose is a carbohydrate that is used as the main source of energy for plant growth, maintenance and repair.

• To get light a plant has many adaptations– Turn leaves– Have broad leaves– Fast growth to gain access to light over neighbouring plants

Protection…• Since they cannot move away from herbivores plants

have developed interesting adaptations to protect themselves

• These include spines or thorns, toxic or bad tasting substances, tough or hairy outer surface.

• http://www.youtube.com/watch?v=H9MV5CgPgIQ• http://www.apsnet.org/edcenter/intropp/topics/Pages/

OverviewOfPlantDiseases.aspx (extra reading)

Nutrients…• Need nutrients like phosphorus nitrogen and potassium

in order to synthesize proteins, lipids and other needed compounds

• Most plants absorb dissolved nutrients from the soil• Others have symbiotic relationships with bacteria or

fungi to get their nutrients• Mycorrhizae- (singular, mycorrhiza). The fungus gets

its energy from the plant, and the plant gets nutrients like phosphorus and copper

• Lichen-The symbiotic relationship of fungi with either algae or cyanobacteria. Fungus produces the body and the algae/bacteria photosynthesize

• Rhizobium bacteria- the bacteria attaches to the roots of plants getting enery and nutrients while fixing nitrogen for the plant

RHIZOBIUM

Micorrhizae

Lichen

Phylogeny

Monocots vs. Eudicots• Both flowering plants (angiosperms)• Eudicots are also known as dicots

Monocots EudicotsFlowers parts in multiples of three

Flower parts in multiples of four or five

Leaf veins parallel Leaf veins in branchesStem vascular bundles scattered

Stem vascular bundles in a ring

Structure of vascular plants…

Structure of vascular..• Underground- root system• Above ground shoot system• 3 main non-reproductive

– Leaves, stems, roots• These are made up of;

– Dermal tissue– Vascular tissue– Ground tissue

• Meristematic tissue(meristem) – actively dividing undifferentiated cells. Found where growth occurs. Become specialized.

Leaves…• Leaves contain many chemical compounds including

tannins, pigments and caffeine.• Caffeine and tannins are both noxious substances to

prevent herbivores from eating the leaves• They are central to photosynthesis, gas exchange,

storage• Contain chloroplasts that absorb the suns energy

because of the photopigments contained within them• A photopigment is a pigment that undergoes a physical

or chemical change in the presence of light.– Most common is chlorophyll (gives plants their green colour)– Absorbs blue and red light wavelengths

• Protection: spikes, thorns, toxins etc.

Epidermis• Waxy cuticle prevents too much water loss• Contains openings or stomata to allow for gas

exchange• Recall that carbon dioxide is needed for

photosynthesis and oxygen is released as a bi-product

• Plants also undergo cellular respiration to convert stored glucose into energy and thus need oxygen to do this

CELLULAR RESPIRATION

PHOTOSYNTHESIS

Structure…

Terms…• Blade-flattened region• Petiole- stem or stalk• Leaflet- compound blade (more than one

flattened region like in a clover)• Venation- the arrangement of veins in a leaf

– Monocots have parallel veins– Eudicots have branching veins

Internal leaf structure• Epidermal cells- outer layer just under cuticle tightly

packed. Prevents water loss and prevents infection from bacteria and fungi. Do not perform photosynthesis, but are transparent to let light through.

• Mesophyll- middle leaf. Contain majority of chlorophyll. Two types;

– Palisade mesophyll- elongated and tightly packed. Contain many chlorophyll.

– Spongy mesophyll - mesophyll cells are loosely packed with large air spaces, which allow for gas exchange between the mesophyll cells and the atmosphere through stomata

Control of Gas exchange• Stoma- A stoma (plural: stomata) is an

opening in the epidermis of a leaf, through which gases pass in and out.

• Guard cells- two kidney shaped cells control the opening and closing of a stoma.

• In terrestrial plants, most of the stomata are in the lower epidermal layer, below the spongy mesophyll.

Vascular tissue…• The vascular tissues (xylem and phloem) are

arranged into veins that run through the spongy mesophyll.

• In aquatic vascular plants Aerenchyma replaces spongy mesophyll. – loosely packed parenchyma cells with large pores

between them. Aerenchyma helps leaves to float on the surface of the water.

– stomata are on the upper epidermis, so they are exposed to the air. Other aquatic leaves do not float and have no stomata.

Leaf Specialization• Protection- contain toxins or have been

modified into spikes to deter herbivores• Winter adaptation- thin leaves easily freeze,

thus trees with these leaves lose their leaves in the winter to conserve water and nutrients

• Gymnosperms do not lose their leaves, they contain chemicals, thick cuticle/epidermis to prevent freezing

Human uses of leaves…• Herbs- parsely, cilantro, basil etc• Tea – cammelia, peppermint• Vegetables- leafy green veg rich in iron and

minerals, such as calcium, potassium, iron, and magnesium, as well as vitamins B, C, E, and K. They also provide nutrients that protect our cells from damage, such as beta-carotene, lutein, and small amounts of omega-3 fats

• Wax- from cuticle. Candle wax, car and furniture polish etc.

Chemicals in leaves…• Poison-

– hydrangea leaves induce vomiting, diarrhea, and/or coma.

– Rhubarb leaves cause nausea, vomiting and sometimes kidney damage

• Medicine– Foxglove- digitalis used to treat heart

disease– Rosy Periwinkle- produces vinblastine and

vincristine, toxins used to treat cancer

Psychotropic chemicals…• Psychotopic meaning they alter perception,

emotion, or behaviour.• Marijuana produces the psychotropic

compound tetrahydrocannabinol (THC).– Increase appetite and reduce nausea, and may

reduce muscle spasms and reduces internal pressure in the eye, for treating glaucoma.

– THC causes distorted perceptions, impaired coordination, difficulty in thinking and problem solving, and problems with learning and memory, which can have serious consequences.

Psychotropic…• Coca plant produces leaves that when chewed

supresses hunger, pain, and fatigue and helps lessen the symptoms of altitude sickness.

• Cocaine can produce euphoria, talkativeness, and alertness. It can also produce paranoia, irritability, and nervousness.

• Highly addictive