I thought a "prediction" was something about the future. But Darwin, if I understand correctly, classified the plant as carnivorous. As it is the title makes you think the plant turned carnivorous since Darwin made his prediction; and make you think Darwin said "This plant will soon become carnivore". But what happened is that his statement has been confirmed, not that the plant changed.
Darwin probably didn’t know this exact species but only other species of the same family and predicted that there are/were some members of the family that are carnivorous
We have been able to predict properties of elements that had not been isolated yet. Your definition is too narrow.
I think prediction is about something you don't know. What happens in the future is that you might come to know.
For example, we predict that there is gold in X location.