Why are some leaves soft and furry-ish?

Question

Why are some leaves soft and furry-ish?

Answer 1

Hairs on a plant offer protection against chewing insects and slow down air movement across leaves to slow evaporation. The last is why so many plants from hotter arid places have grey appearances, they are covered in hairs or even thorns. Cacti use dense shields of spines, other plants use hairs to provide a still air layer over the leaf surface. Less convection or air movement next to the plant's surface means less water loss.

Sempervivum arachnoideum are a bit more extreme than other plants but this is natural to them

http://davesgarden.com/guides/pf/showima...

http://davesgarden.com/guides/pf/showima...

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

http://cat.inist.fr/?aModele=afficheN&cp...

Mechanisms of herbivory defense in plants – inducible & physical.

http://www.isb.vt.edu/proceedings99/proc...

http://www.sbs.utexas.edu/mauseth/Resear...