Subdivisions of a variety, alike in structure, but different in certain physiological, biochemical, or pathological ways.
A particular group of parasites, mainly fungi, exhibit a distinctive adaptation to various types of crops belonging to a single host species. The International Botanical Congress, which took place in Amsterdam in 1935, advised that the term “physiological race” be employed in lieu of “physiological form.” Additionally, other equivalent terms include physiological form (or race), biological form, and frequently, race.