Cross Section of Root Diagram

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Xylem transport of water Root Pressure- force that helps to drive fluids upward into the

water-conducting vessels (xylem)

Root pressure is caused by active transport of mineral nutrient ions into the root xylem.Without transpiration to carry the ions up the stem, they accumulate in the root xylem andlower the water potential. Water then diffuses from the soil into the root xylem due toosmosis. Root pressure is caused by this accumulation of water in the xylem pushing on therigid cells. Root pressure provides a force, which pushes water up the stem, but it is notenough to account for the movement of water to leaves at the top of the tallest trees. Themaximum root pressure measured in some plants can raise water only to about 7 meters,

and the tallest trees are over 100 meters tall.

ADD the effect of :

Transpiration- Transpiration removes water from the leaf byevaporation of water from spongy mesophyll of leaves.

Transpired water is replaced with water from the xylem, pulled by capillary action(Transpiration Pull)

This movement is called transpiration stream.

Low pressure is created inside xylem vessels when water is pulled out (transpiration pull).

Xylem vessels contain long, unbroken columns of water where the pressure is transmitted

across. To equalize the pressure, water travels up the vessels through its property of cohesion
http://en.wikipedia.org/wiki/Active_transporthttp://en.wikipedia.org/wiki/Roothttp://en.wikipedia.org/wiki/Water_potentialhttp://en.wikipedia.org/wiki/Osmosishttp://en.wikipedia.org/wiki/Treehttp://en.wikipedia.org/wiki/Treehttp://en.wikipedia.org/wiki/Osmosishttp://en.wikipedia.org/wiki/Water_potentialhttp://en.wikipedia.org/wiki/Roothttp://en.wikipedia.org/wiki/Active_transport


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Abiotic Factors andTranspiration

For each bullet, tell if transpirationwould increase or decrease.

Increased temperatures ___________ Decreased temperatures __________

Increased wind _____________

Decreased wind _____________

Increased humidity ___________

Decreased humidity ___________

hih h


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ChihuahuanDesert Landscape


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Mojave Desert Landscape


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Great Basin Landscape


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Sonoran Desert Landscape


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Russian sage


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Ocotillo


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Juniper


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Yucca

Yucca is alsocalled theSpanish Dagger

because it haslong, narrowleaves withneedle-like

points at theends. It grows onrocky slopes andthe hot desert

floor


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CreosoteThe Creosote Bush grows in areasthat are very hot and dry. The soilcan be almost pure sand. When it

competes for water with anotherplant it almost always wins. It loseslittle moisture from its tiny curledleaves.


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Prickly Pear Cactus

Prickly Pear Cactus grows in mostof the deserts of America. It haslarge, sharp spines that stick outfrom thick, water-holding padsthat look like leaves but are really


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In comparison:Rainforest and Jungle plants


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Rainforest and Jungle

plants


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In comparison:Rainforest and Jungle plants


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ow ave eser p an sadapted to reduce

transpiration? Reduced leafsize

Rolled leaves

Spines

Low growth

(bushes morethan trees)

CAM-

crassulacean

Deep roots

Thickened waxycuticle

Water storagetissue in stems(succulents)

Fewer stomata

Stomata in pits

surrounded by


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Compare and contrastCAM Metabolism and

C4 Physiology in plants.Relate to how this makes

them better adapted to adryer climate.

Homework:

Documents

Cross Section of Root Diagram