A similarity law in botanic. The case of hydraulic conductivity of trees A.G. Meyra, G.J. Zarragoicoechea and V.A. Kuz Eur. Phys. J. D, 62 1 (2011) 19-23 Published online: 21 September 2010 DOI: 10.1140/epjd/e2010-00242-1