They eventually reveal the same conclusion, but with less certainty: > The answers to the “Why so tall?” and “Why not taller?” questions seem to involve water,

They eventually reveal the same conclusion, but with less certainty: > The answers to the “Why so tall?” and “Why not taller?” questions seem to involve water, as is the case for so much about trees. > Ultimately, it’s most likely a matter of hydraulics: A tree’s height appears to be limited by the enormous effort needed to lift water through tiny tubes, or xylem — the transport tissue that constitutes most of its mass.