Serpula (fungus) are formed. The strand mycelium of "Serpula", which can be up to 8 mm thick, are invasive and can spread over non-nutritive surfaces to find new food sources, even spreading through pores in stone, brickwork, and cement. After its initial growth period, the fungus can produce the water it needs and can continue growth into dry timber, eventually degrading it to powder—hence the term "dry rot". "S. lacrymans" is the most serious cause of building timber decay in the UK and northern Europe. The "Dictionary of the Fungi" (10th edition, 2008), suggests that the genus contains two species. , the
Pulvinic acid Pulvinic acid Pulvinic acid is a natural chemical pigment found in some lichens. Dimers of pulvinic acid have been found in the fungi "Scleroderma citrinum" and "Chalciporus piperatus". Hydroxypulvinic acid pigments (pulvinic acid type family of pigments) have been found in "Boletus" (e.g. "Boletus erythropus"), "Boletinus", "Chalciporus", "Gyrodon", "Leccinum", "Pulveroboletus", "Suillus" (e.g. "Suillus luteus", "Suillus bovinus", and "Suillus grevillei"), "Paxillus" (e.g. "Paxillus involutus"), "Serpula" (e.g. "Serpula lacrymans"), "Xerocomus" (e.g. "Xerocomus chrysenteron"), "Hygrophoropsis" (e.g. "Hygrophoropsis aurantiaca"), "Retiboletus" (e.g. "Retiboletus nigerrimus"), "Pulveroboletus" (e.g. "Pulveroboletus auriflammeus"), and are generally characteristic of Boletales. Derivatives and similar pigments of this family include atromentic acid, xerocomic