How universal are these fields, though? Many of the plants in the database are not cultivars, perhaps not a majority but certainly a substantial minority at the minimum. Even of the cultivars, many (most?) are not hybrids. In those cases, a "Hybridizer" field is going to seem odd. Also, Year of Introcduction is often not as simple a thing as one would think it should be. The American Iris Society, for example, treats year of introduction and year of registration as separate data points. Many official registers for other groups of plants do not.
