Phytophthora is not a true fungus, although it shares many features with the fungi. There are many species, and the differentiation between individual Phytophthora species can be extremely difficult. Although identification requires a high degree of expertise and training, it is important as species can vary significantly in their aggressiveness as pathogens. There is much debate and confusion in the characters used to define species, but general features such as colony morphology, and the production of structures such as sporangia and oospores are the basis of the taxonomy. It is likely that molecular techniques will become the best method for identification in the future.