January 7 ~Feb1 2013
Midterm date: Monday Febuary 4 2013. 5-7pm
Module 2: Begins on Tuesday Feb 5 . th
Total: 12 lectures
1-2: Tree of life-plants
3-4 Plant cells and plant tissues
5-6. From seed to tree
7-8. From tree to seed
9. Transport in plants
10. Plant nutrition and soils
11. Plant defense
12. Plant life on the edge.
Lecture 11 notes (plant defense)
A) Plants feed the world, but they do not really want to do so . . .
Herbivory: the most widespread plant-animal interaction. Often least visible.
Insect miners: between epidermis
B) Plants defense mechanism
Tissues and organs
Chemical defense Primary vs Secondary-toxin compounds
Primary compounds-products of photosynthesis, protein synthesis such as
carbohydrates, proteins, starches, cellulose. Simple essential to normal
cellular function and life in general
Secondary compounds: products have no known direct function in basic
o Huge complexity of compounds, strict control of syntheiss
o Chemical weapons agaisnt herbivores include toxins: saponine,
cyanide, atropine, strychinine, caffeine, cannabinol, mustard oil,
Defense mechanism can be systemic-always present or induced-sometimes present.
Physical defense: mostly systemic.
Chemical defense: often induced.
There are 4 types of defense mechanism:
1. Systemic physical
Trichomes: hair to prevent exposure to usn, used against herbivore
Passive hiding. Lithops.-pebble plants in Kalahari desert making them
hardly eaten. They are filled with water and more apparent after rain
when the flower shows.
Active hiding: touching leaves that fold in which it is triggered by
electric current where signals travel through phloem
Make-believe: look like it’s eaten. Mimics insect eggs. (e.g passion
flower, virginia water leaves. White blotches intepret for other insects
have eaten it already)
2. Systemic chemical
Cyanide in Bracken fern Cyanogenic glycosides ( Pteridium
aquilinum). This poisons cattle and cause blindness/cancer to
Poison ivy (toxicdendron radicans). Leaves of 3 with longer leaf stalk.
Oil on your skins + phototoxin.
Systematic physical and chemical: stinging nettle: urtica dioica. Has
thorns and pois