1. Plant Tropisms

2. What are we talking about? Emergence - An outgrowth, as a projection, on the surface of a plant Force – A push or a pull Turgor Pressure - pressure exerted on the plant cell wall by water passing into the cell by osmosis Tropism – an involuntary response of an organism to a stimulus (in plants)

3. Tropisms 101 Stimulus – something that causes a action from an organism. Response – an action or condition that is a reaction to a stimulus  Negative response – when the growth of a plant is away from the stimulus  Positive response – when the growth of the plant is towards the stimulus

4. Types of Tropism We are going to be studying 3 Tropisms: Hydrotropism Gravitropism AKA “Geo”tropism Phototropism

5. Hydrotropism: “water” Stimulus: Water Response: A plant’s roots grow toward the source of water IIIIs this a positive or negative response?

6. Gravitropism: “Geo” Stimulus: Gravity Response: 2. Positive – the roots grow downward, towards gravity 1. Negative – the stalk grows upward, against gravity N P

7. Phototropism- “light” Stimulus: Light Response – the plant grows in the direction of a the light (it only comes from one direction)  What type of response is this?

8. Other types of Tropisms

9. Thigmotropism Stimulus: Touch Response – the leaves (or part of the plant that is touched) move or coil away from the touch, or trigger some other action  Example: The Venus Fly Trap is a plant that shows thigmotropism. It closes when a bug or some other object touches it.

10. Thermotropism Stimulus: Temperature Response: a plant grows in the direction of/away from a source of heat or cold EEEExample: In the first picture, this tree has a positive response to the cold and grows toward the heat. EEEExample: A plant called a Rhododendron curls its leaves away when it experiences cold weather.

11. Heliotropism Stimulus: Sunlight Response – a plant grows or turns to face the direction of the sun  Example: Young Sunflowers face the sun all day long. As the sun goes across the sky, the sunflower turns so that it is always facing it.  Is a Sunflower growing towards the sun an example of Phototropism or Heliotropism?

12. References Pictures:   http://virtualastronaut.tietronix.com/textonly/act25/images/hydrotropism. gif http://virtualastronaut.tietronix.com/textonly/act25/images/hydrotropism. gif   http://k53.pbase.com/u48/roving_rube/large/30489110.a.c.birch.jpg http://k53.pbase.com/u48/roving_rube/large/30489110.a.c.birch.jpg   http://www2.brevard.edu/jefrick/rhod.htm http://www2.brevard.edu/jefrick/rhod.htm   http://www.xtec.cat/~mherna23/summer03/amspot/picture/gravitropism. gif http://www.xtec.cat/~mherna23/summer03/amspot/picture/gravitropism. gif   http://img1.photographersdirect.com/img/17231/wm/pd1198793.jpg http://img1.photographersdirect.com/img/17231/wm/pd1198793.jpg   http://wpcontent.answers.com/wikipedia/commons/9/9d/Dionaea_musci pula_closing_trap_animation.gif http://wpcontent.answers.com/wikipedia/commons/9/9d/Dionaea_musci pula_closing_trap_animation.gif   http://img1.photographersdirect.com/img/17231/wm/pd1198796.jpg http://img1.photographersdirect.com/img/17231/wm/pd1198796.jpg   http://farm2.static.flickr.com/1423/1402179998_4e1712d584.jpg http://farm2.static.flickr.com/1423/1402179998_4e1712d584.jpg Information:   http://www.hasc.qld.edu.au/csnotes06/biowedGG/Notes%20for%20San dra/Plant%20Tropisms.doc http://www.hasc.qld.edu.au/csnotes06/biowedGG/Notes%20for%20San dra/Plant%20Tropisms.doc   www.wikipedia.org www.wikipedia.org