obsolete viable mixed vegetative cell population including cell with normal morphology and long cells true This term was made obsolete because a "mixed population" observation would be better represented as two or more separate phenotype annotations, each with penetrance specified. long low penetrance midori 2013-06-04T15:36:23Z FYPO:0002180 OBSOLETE. A mixed population phenotype in which cells in the population are viable, some cells are longer than normal, and the rest of the cells are of normal morphology (i.e. size, shape, and structure).