You know what, 
shioyama is absolutely right: the song is exactly the one he gives the link for, and the parts that are missing from the original text here are indeed essential for understanding the proper meaning of the song lyrics.
So, rather than punish him for his excellent detective work, I'd like to applaud him for it and approve this translation as it stands now, even though there are two lines added to it which aren't in the original.
Anyway, the other option is, we can put those two extra lines in the notes only, but it would be a shame to screw up his already-excellent notes.
What do you think, Lilly?
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Hello,
shioyama, great work!
You keep this up, and we'll be making an Expert out of you yet!
Only one point, and it's really a judgment call: I think it is the
flower here that drops the seed as it fades. As you know, the subject isn't given in the Japanese, but I believe this is what is implied here. What do you think?