The term "dry rot", or "true dry rot", refers to the decay of timbers from only certain species of fungi that are thought to provide their own source of moisture and nutrients to cause decay in otherwise relatively dry timber. However, there has been no published experimental evidence to support the phenomenon. In modern texts, the term 'dry rot' is used in reference to damage inflicted by either: "Serpula lacrymans" (formerly "Merulius lacrymans") predominantly in the United Kingdom and northern Europe; and/or "Meruliporia incrassata" (which has a number of synonyms, including "Poria incrassata" and "Serpula incrassata") in North America. Both species of fungi cause brown rot decay, preferentially removing cellulose and hemicellulose from the timber leaving a brittle matrix of modified lignin.