CAREFUL INVESTMENT PLANNING. “Leaves do not transport fixed carbon until nearly mature; instead they act as a speculative drain on the limited supplies of root minerals and water. Likewise roots only sequester minerals in their mature regions. Inaccurate speculation, that is poor decision-making, can waste valuable resources and short shrift can be expected in the Darwinian struggle.”
http://link.springer.com/article/10.1007/s00114-005-0014-9