There’s a whole family of songs associating flower imagery with heartbreak and loss of innocence, variously featuring grass, roses, willow, thyme and rue (the last two coming with fairly unsubtle wordplay). This and the next are both examples, although they aren’t in any obvious sense variants on the same song.
I learned this song from Jacqui McShee’s unaccompanied recording on the Pentangle album Cruel Sister; I remember being particularly struck by the lack of a copyright credit on the label. (No need: there was no composition and no arrangement, just a traditional song.) I also liked McShee’s controlled, restrained delivery: the song was rendered in exactly the same way, verse by verse, with exactly the same ornamentation and almost no change of emphasis or volume. I liked it, but I haven’t emulated it. There’s even accompaniment (flute, mostly recorded in the bathroom).
The key signature of this one had me puzzled – it appears to be in F, but an F/C drone sounded totally wrong, and D/A for D minor wasn’t much better. It turns out it’s in G Dorian, i.e. a scale from G to G played with one flat. The drone you hear (on recorder) is G and D, or rather D, G and D.