Deep in a shaded wood, a blueberry bush that has struggled for light finally flowers. A bumblebee visits, and now a green berry is beginning to swell. The speaker watches this with quiet delight, and the exclamation in "a perfect yellow bell!" lets that happiness show.
Then the poem looks ahead. The speaker wonders which bird will find the berry once it turns blue, and how far its seeds might be carried. These questions turn one small plant's good year into something larger: a chain of events that could reach well beyond the bush. The line "That's how suddenly the future can change on you" feels both wondering and a little startled, as if good luck can arrive as unexpectedly as bad.
The closing three-line image, with striped shadows on the forest floor and a swallowtail, works like a breath after the thought. The mood is gentle, observant, and hopeful, with a sense that small things matter.