Answer:
What has roots as nobody sees, is taller than trees. Up, up it goes, and yet never grows?
What flares up and does a lot of good, and when it dies is just a piece of wood?
My first is nothing but a name; my second is more small; my whole is of so little fame it has no name at all.
A precious stone, as clear as diamond. Seek it out while the sun's near the horizon. Though you can walk on water with its power, try to keep it, and it'll vanish in an hour.
It's usually found dried, but often kept slicker. Above another need, it's said to be thicker. What is it?
If it’s information you seek, come and see me. If it’s pairs of letters you need, I have consecutively three. What am I?