The Flashing Archwood Sapling from Ars Elemental cannot be grown in a botany pot while the other saplings from Ars Nouveau can (Vexing/Blazing/Cascading/Flourishing)

BotanyPots version : 9.0.31
BotanyTrees version : 5.0.4

Ars Nouveau version : 3.13.2
Ars Elemental version : 1.19.2-0.5.8.2

Minecraft version : 1.19.2
Modpack : All the mods 8
Modpack version : 1.0.17

Thanks for letting me know. This should now be fixed in 5.0.8 on CurseForge.