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Peltigerales (subdivision Ascomycotina) An order of lichens, in which the thallus is foliose with a cortex on the upper surface and often also on parts of the lower surface, which is often marked with vein-like ridges, and may or may not bear rhizines. The asci turn blue when treated with iodine. Spores have 2 or more transverse septa, and are colourless to brown. Species are found on soil, rotting wood, etc.