Interspecific Transfer of Ca‐45 and P‐32 by Root Systems

The extent and rate of interspecific translocation of P—32 and Ca—45 were determined when radiosotopes introduced into stumps of seven red maples were found in leaves of 19 other species which were up to 24 ft from the donor maples. The mode of interspecific transfer may be either by exudation from the donor and absorption by the acceptor species or through mutually shared mycorrhizal fungi. Root grafting probably is not important in transfer. The importance of recognizing the root mass of an ecosystem as a functional unit, rather than an association of independent entities, is emphasized.