The lightest wood in the world

This is a book about The lightest wood in the world and I have been reading it and I have found out that they were going to save the seed because the possums have been eating them in the bushes.There are green whau and brown whau and i think that the green whau will float if you put four lemons on it and because it is very light and I think that the brown whau will sink because it is heave.