Questions about leaves...?

Question

How does an aquatic plant and a typical dicot/dicotyledonous plant differ in their methods of gaseous exchange?

What is the significance of epidermal hairs on some leaves? Other than epidemal hairs, what other special features are there on such leaves??

Finally, leaves commonly have their stomata found on their lower surfaces. I read somewhere that there are leaves with stomata ONLY on their upper surface! Is it possible? If so, where can we find such plants?

Thanks! :)

Answer 1

Most dicotyledonous plants have stomata on the lower surface to conserve water. Monocotyledonous plants have stomata on both sides of the leaf, because their leaves are always at an angle relative to the sun. Floating plants have stomata only on the upper surface. Submerged plants have no stomata at all.

Hairs on the leaves make the leaves less palatable to caterpillars and other animals. Other structures include trichomes, hairs with barbs and sometimes with irritants or poison.