Some plants have fine hairs in their leaves and stems, what advantage does this give them?

Question

Some plants have fine hairs in their leaves and stems, what advantage does this give them?

Answer 1

Just a guess but, helps hold water on the plant surface longer?

Answer 2

Two main functions are water retention and protection from being eaten by chewing insects or browsing mammals. The hair (called a trichome) slows down the air moving across the leaves to slow evaporation from the stomata and prevent them from wilting. Less convection or air movement next to the plant's surface pores means less water loss. Many plants appear silver or grey because they have so many fine hairs they shade the leaf surface or reflect sunlight. This is more common to hot dry climates.

http://www.botgard.ucla.edu/html/botanyt...

In other plants the hairs are also a mechanical defense against herbivores. A very common weed the mullein has microscopically fine branches in its leaf hairs. This gives the plant a very stiffly fuzzy feel to us but stops chewers like grasshoppers and even grazing mammals.

http://www.invasive.org/browse/subject.c...

http://www.microscopy-uk.org.uk/mag/inde...

http://www.backyardnature.net/hairs.htm

http://botany.cs.tamu.edu/FLORA/Mint.Spr...

http://botany.cs.tamu.edu/FLORA/pic03/DS...