How can i made a Lava plantm

Im not sure if it's possible to have an actual plant. But you could have a normal block that's supposed to represent a plant, similar to logs, or cacti. But otherwise Im not sure its possible.

You can do a block that spawns in lava that's themed to be like a plant (Such as a log or cactus).
But I don't think you can have an actual plant spawn in lava, without it breaking instantly at least.

Well, there's a few ways you could. First I think of is just by having it spawn like any normal block, but have it only be able to spawn in lava, instead of the usual stone. As a extra requirement, in the additional requirement section. Have it check if the block under is air, and if it is air, then have it return false.

If you want a more built plant like a tree, then I would recommend building it as a custom structure that spawns with the same requirements.

In the spot where you set the things such as generation height, group size, stuff like that.
Should be the last section when editing a block.