I posted this over on twt, but I'll put it here too:
The lotus and the sunflower ideas I took from P from our chat :3 they felt really fitting
Details under the cut ↓
The explanation as to why there are several for some is..I simply thought they were all fitting and couldn't decide between them </3
I did find the lotus flower very fitting for Tendou, but also Parijat was just too perfect to pass up. Both flowers are connected to divine beings in a way and that's very Tendou.
My thought process with poppy for Kagami was because of Gatack being referred to as the deity of war. (Also *blue* poppy cause Gatack lol...ik the red is very important within the poppy symbolism cause it ties in with blood, but I feel like it still being connected while having a different color can sort of serve as hope. It's very fitting for Kagami I think)
Hiyori as a tulip makes sense I think 😭 quite literally within the canon of the show lol..
For Yaguruma: cornflowers 🐝 vs Yaguruma-sou 🦗. Got the idea from wonderful fanart by @/torimerai0713 on twt 💖
I really like the idea of both hellbros having clovers as their flowers though. My recent art is about this lol
A dodder plant felt very fitting for Kageyama seeing as he very much is dependent on others and doesn't seem to have a sense of his own identity. A parasitic plant just makes sense (funnily enough, it's one of my fav plants lol..)
My fav flower!! Forget-me-not...a devastating pick for Tsurugi 🥹 although I do feel like roses also fit him, seeing as them being present during human!Tsurugi's death too; asphodels are also perfect, "the haunt of the dead"
I really don't have a deeper reason for Daisuke...these flowers are very common in the mountains back in my village and they just look and feel like Daisuke to me. It was an immediate pick solely on my memory alone (struggled to find the flower as I only remembered the visuals lol..)
Giten!! Adder's tongue..First off I think it looks like dark Kabuto lol.
Secondly, its symbolism is deceit. I think whether it be mimicry from Tendou, or the fact that he himself was deceived and turned into Giten is very fitting (and heartbreaking)
Jyuka being a sunflower (much like the Lotus for Souji) was P's idea and it felt so fitting and cute 😭💖
That was all for this!!! BUT Nao also made really good suggestions in the replies so I want to include that too:
"hydrangea for kagami (‘blooms after the rain’) and aster tataricus for tsurugi (‘i won’t forget you’)"