This phylum is often referred to as liverworts. They have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information. It is estimated that there are about 9000 species of liverworts. Liverworts have a thin, leathery body that grows flat on moist soil or on the surface of still water. Most liverworts have a thallus, which is a plant body. There are approximately 8,500 species of liverworts. They are widely distributed, occuring from the artic to the tropics. Although some grow in dry places, most liverworts occur in places where moisture is generally available on damp soil or moist rotting logs; a few even grow under saline conditions.