Lyric discussion by bueller84 

Cover art for Black Plant lyrics by Last Shadow Puppets, The

I haven't entirely figured out why I think this song is about two different stories of adultery or cheating, but that's my theory..

In the first verse, it seems like a girl cheated on her guy (she's been misbehaving), she told him and he is extremely pissed and probably told her to get lost (he hadn't deal with how you felt with ways that suited you). She wants to apologize to him by writing him a love letter, but she knows that letter is probably not going to work because she cheated, and that's that.

The second verse is a man who is probably not feeling satisfied in his current relationship situation, hence, "tenderness aplenty, but that wasn't what you craved."

So then temptation greets him like a naughty friend ("desire starts to make demands") and he strays, even thought he narrator warns him, "you'd be a fool to make your plans with her."

So that's why the chorus says "why would you say sorry?" Can you really apologize after you've cheated and have your significant other understand where you're coming from? It's why the girl never sent the love letter; it wouldn't have made the guy feel any better! It's one of those few things you can honestly control and to do it is just wrong, so an apology after cheating is kind of worthless because you had a choice over what you were doing.

I think "when it's just one of many bullets you will bite while waiting for a ray of light," means that after the guilt of cheating sets in, and they've apologized, they will sit there (in pain from the guilt) trying to justify their behavior.

...And I guess after all of that, I still have no clue why the song is called "Black Plant."