Sadly, I'm not a great spriter. I'm just learning how to sprite right now and tying to figure out shading. There may be other people who can do such sprites or have ideas for new flowers, but I don't know.
I feel like allowing users to make new plants will make this site more exciting. Something similar to what many adoptables sites are doing, as it would put less strain on one spriter and it would allow more involvement from members. Still not too sure why this isn't the case though. It'd be nice!