The data items can be separated by spaces, commas, or any other character. This type file is much larger than a binary file. In this format each data item must carry its own identifier, further increasing the size of the file. The only reason for using this type file is when the program does not know anything about the data it is comparing. In which case it cannot make any judgments, the data either matches, or it does not.
All further discussion is related to binary files.
Each species record should contain the name of the mushroom and associated descriptive data. A major difference between a database and the verbal description in a field guide is that if a characteristic is not considered important, it usually is not mentioned in the field guide. But if a characteristic is important enough to include in a database when it occurs, it is also useful to know when it does not. The mushroom in question does not have latex, obviously it is one of the remaining Russulas. But, if we can't indicate that negative fact, there is no way to narrow the list.