The humongous fungus
Armillaria gallica is a root-pathogen of forest trees that spreads by rhizomorphs
Smith et al. collected Armillaria cultures using wooden baits, as well as tissue and spore cultures from fruiting bodies
Using RFLP and RAPD (random amplified polymorphic DNA) analyses, they showed that individual clones of Armillaria can be very extensive
The largest occupied 15 hectares, with a mass of 10,000 kg, and age of 1500 years.
Smith , M., J. Bruhn and J. Anderson, 1992. The fungus Armillaria bulbosa is among the largest and oldest living organisms. Nature 356:428-431
Gould, S. J. 2992. A humongous fungus among us. Natural History July, 1992, p. 10-14.