Two varieties are Cottonwood and Mulberry
Royal Empress
Who knows the stem is it yes the stem and root. Who knows the stem is it yes the stem and root. It is the roots.
In temperate zones it is probably Cupressocyparis leylandii.
Conditions being equal the fastest growing oak tree is the Northern Red Oak. (Quercus rubra)
Because the climatic conditions above that level are not conducive to tree growth.