Originally Posted by
billl
Hi, Miyako! Nice to see you posting around here again. You've been posting a lot and the stuff I've seen has been pretty artful and interesting, as expected.
I don't think "on" would be worth criticizing as "incorrect" usage in a poem in this case--that would seem pretty nit-picky to me. But, in regards to the different depths of meaning you next mention: "weeds" (in English, at least) have a particularly strong association with the idea of tenacity. So, beyond the in/on matter, I think it might be a little unorthodox to use it as an image suggesting a "fleeting" aspect of something. That might be beside the point though, and again, I really hope no one took you too strongly to task about using "on" in that case, I certainly wouldn't be surprised to see it there or put out by its use (as long as the pile of droppings can be imagined large enough to host weeds, I guess).
Your use of "the" before "birds' droppings", and the decision to omit "the" before "weeds", are both completely right, and show a completely standard (but at the same time, creative and interesting) application of the definite article. It would be ridiculous if anyone were to criticize those choices, and the choices have exactly the effect you intend.
Of course, there might be a larger mission for your OP, and I don't mean to just zoom in and offer a couple opinions on a couple specifics, as if you were simply asking about syntax/grammar. I can't really add much to your own musings about the literary identity crisis you describe. To me, it seems you are aware of and interested in the issue of "correct" English grammar, and that's enough. がんばってください! (I hope the "!" isn't too much there...) Though I do think it must be a little annoying to face a problem that really is, once you've gotten where you are, pretty much 100% about "habitual usage" (despite the often interesting histories and logic behind those habits), as you say. I used to know quite well a woman who was fluent in five languages, but had 100% fluency in none of them--imagine that... The habits take time, and the grip of the roots--well, you'll probably find ways to more reliably make use of them in ways that serve your work, and keep growing new roots besides.