A rooting media in the form of a resilient, integral body of spongy open-celled hydrophilic polymer forming a first essentially continuous phase extending throughout the body and having passages therethrough forming a second essentially continuous phase extending throughout the body, a quantity of particles...http://www.google.es/patents/US4196543?utm_source=gb-gplus-sharePatente US4196543 - Rooting media and methods of making the same
