I see a lot of genus usually change their family as someone investigate its nature or its genetic, but what called my atention was the mimosaceae and amaryllidaceae families.

Without much observation I see a difference between a mimosa and a pea, or a lillium and an hyppeastrum, so it seems logical to my ignorance that this are true families and not just agrupations inside a big family... but I suspect there must be a real reason why sites like plants.usda.gov for example don't seem to follow this order. I understand all mimosaceae fit inside the fabales order, but why such an apparent flowers difference would be just one family??

This small discovery triggered my paranoia, because there might be a lot more of similar differences which I'm not aware of, and I don't know where to start finding info about it....

Thank you. Paul.