Wednesday, February 10, 2010

Explain the function of the cuticle, guard cells, and leaf hairs with regard to transpiration.?

The cuticle is a waterproof epidermal layer that blocks water loss. The plant will have a cuticle thickness proportionate to their habitat's aridity. The stomata are regulated portals that control both the rate of water evaporation and permit the diffusion of gases. Leave's shape, color, and surface texture all play a part in transpiration as does the number of stomata/area. Some stomata are sunk in depressions, some are only on the underside of leaves while floating water plants must have stomata on their upper surfaces.


Leaf surface plays a role by controlling the air boundary layer. Air is slowed as it moves across the leaf surface producing a boundary layer. Large leaves have more boundary layer than small ones. This is a quieter layer of air as it touches the leaf. The presence of hairs or leaf texture to hold a deeper boundary layer of air slows transpiration further.

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