Kriske's contribution to Effective Procedures and Computability. It takes no energy (supplied by the tree) to erase a symbol in a Tree's Turing machine.

Alan Turing had an interest in Biology and found that the patterns that leaves and plant structures had could be evidence of effective procedures used by the plant to calculate the structures.  Another person who had a deep interest in trees was Einstein, whose first paper was on capillary action.  Einstein was interested in the capillary action of trees because it took no work for the tree to pump the water hundreds of feet into the air.  A typical poplar tree pumps about 100 gallons of water a day into the atmosphere, a typical Red Wood, about 500 gallons a day (precise values can be obtained from the literature on trees).  This author proposed a mechanism for the pumping of water, that allowed for binding energy to be overcome by photons striking the water/capillary surface in the tree.  So classically, no work is done but quantum mechanically, the "work function" allows the water molecule to be ejected, when the photon is the proper energy to overcome the binding energy of the water molecule to the surface of the leaf, or in many cases to the capillary tube itself.  The ejection of the water molecule creates a "hole" in the water column that propagates down the tree and into the soil, where another molecule of water is attached.  This occurs in the Xylem, and the cell that makes up the tree, has contact with both the Xylem and the Phloem.  The cell is signalled when the "hole" propagates and much like the "erasure" that Feynman considered to be the "Fuel" in Turing machine computations. It takes no work to pump water up a tree, the tree also "cools" without doing any work and as can be plainly infered, the tree does Turing computations without any loss from erasures.  One could claim that the energy loss is the sun's loss of energy, but in many ways that makes no sense, as the sun is the "environment".   When the "hole" propagates from the leaf downward, the "head" which is the cell and many cells, metabolizes.  The "hole", or the tape, moves in one direction due to the photoelectric effect, but the "head" synthesizes proteins and other molecules and places them into the adjacent water column, where the specific gravity of the column is changed.  The Turing tape then has the ability to change directions, or another tape changes directions (xylem and phloem) and a recursive function can be realized, with a chemical computer being realized, with algorithms for structures.