When two plants which are closely related are difficult to tell apart there is no surprise, but when two plants which are not even in the same plant family look a lot alike, that's kind of perplexing! Consider the example of Achillea millefolium (member of the Sunflower Family) and Horkeliella purpurascens (member of the Rose Family): Although once they have produced flowers they are easily distinguishable, early in the spring when their leaves are first emerging from the melting snow they can look almost identical! Although the mature leaves are only somewhat similar, the young leaves can look nearly the same. This is in part because Achillea millefolium (aka, Yarrow) can be highly variable, especially when it comes to early leaf structure. At any rate, there are probably dozens of similar examples, but the doppelgangers which inspired this song are Achillea millefolium and Horkeliella purpurascens.