I've been talking with Debby a bit about the lyrics to "O Tannenbaum" ("O Christmas Tree"). The versions I learned start with the lines:
O Tannenbaum, O Tannenbaum,
Wie treu sind deine Blätter!
O Christmas Tree, O Christmas Tree,
How faithful are thy branches!
Debby, the German, claims the lyrics she's always heard are "Wie grün sind deine Blätter!" Which makes just as much sense, I suppose, except that the third line goes, "Du grünst nicht nur zur Sommerzeit" and the repetition of grün is rather unappealing. And most English translations use some version of "treu", usually "faithful" or "loyal" or "steadfast" or something like that. I must comment, too, that I love the verb grünen meaning "to be green"; English has verbs "to brown" and "to yellow", but they refer to becoming brown and yellow, rather than simply being those colors.
One curiosity that doesn't make sense---though I admit I never noticed it until Debby pointed it out---is that Tannenbäume (fir trees) don't HAVE Blätter (leaves)! I agree that Nadeln (needles) just doesn't sound as nice, but that's some serious botanical license there. The English version is pretty clever, since we can talk about the branches being faithful without specifying how!