some people with amazing eyesight and attention to detail have noticed a yellow pixel seemingly attaching to the knight during their confrontation with Flowery, and there's speculation that Flowery attached a seed to them as a tracker.
(Source: u/K0uzan on r/Deltarune.)
i have been baffled by a few lyrics in Flower Man since it dropped. The song seems to possibly be about both Flowery and Asgore at different points, but even with that ambiguity some of it doesn't quite make sense.
Another thing that puzzled me was Flowery's dialogue about sensing something beneath the town. Flowery... lives on a countertop. He may have been grown in Hometown's soil, but he hasn't been physically connected to it for presumably many years.
[battat conspiracy board] So Here's What I'm Thinking.
Flower Man, Flower Man
With his heart in the sand
So he stands
To watch the whole wide world
From a can
Yet the every daily
Hope that powered the Flower Man
Would never cower off of its path
Even if broken I am more than glass
Everyone, listen carefully to me. Us plants, are neither Darkners nor Lightners. We are living beings… that take on new consciousness in the dark. We can feel things others can't understand…
Something horrible is stirring underneath the town. A darkness beyond your imagination.
I think Flowery is just one of many buds grown from the same root system, which is still in the ground. His heart in the sand. (I think this line also has a double meaning about Asgore burying himself in his work and ignoring the world around him.)
I think Flowery maintains some kind of connection to those roots, and the other flowers that sprout from them. Including some of the flowers Asgore keeps giving to Toriel. It would make sense that he's trying to woo her with the same types of flowers he grew for their wedding bouqet. And those flowers keep ending up in the trash in Toriel's house. Watching the whole wide world from a can.
Yet the every daily
Hope that powered the Flower Man
Would never cower off of its path
Even if broken I am more than glass
Nothing is stronger than... a... Flower's... dream...!
are, collectively, a reference to the Shadow Crystals.
This is the same chapter where Seam explicitly lays out that the crystals contain "the power of lost dreams," and that "when a strong attachment is formed… when a dream is gripped tightly… and then broken off. These… are the shards that remain." Notably there is nothing this time to suggest that it has to be a Lightner's lost dream. And Plantners are their own unique category of entity that seems to follow a different set of rules. So there's a distinct possibility that Plantners can produce Shadow Crystals.
Flowery's dream revolves around Asgore, but Asgore rejects him. And even if he hadn't, Flowery was not going to survive long enough to really see it through. All the other wedding bouquet Flowers get their "thank you for watching my dream" goodbyes, but Flowery doesn't. We didn't get to watch his dream, because his dream was never achievable.
Flowery seems to know a lot more than the average chapter boss. He outright discusses the Prophecy with Ralsei. I think it's possible he knows about the Shadow Crystals and is deliberately seizing the power from his own lost dream before it can turn into one, allowing him to survive his encounter with the Knight long enough to stick a piece of himself to their armor.