1) [Nature(Intelligence)]: Check the plant to see if you recognise it before you answer her.
2) [Nature(Wisdom)]: Observe the plant and see what it tells you about itself before you answer her.
3) “Okay, do your plant thing, I'm ready!”
4) “I don't trust your plant thing, hands off!”
5) [Draw your weapon and attack] (Because this is a Larian game...)
This sounds acceptable to me ...
Either that, or i had in mind another possibility that Variant check will be rolled after first check failed. Since we allready know that Larian have no problem with puting 3 or more dicerolls in the row against us ... therefore it would be nice to see two dicerolls in the row in our favor sometimes.

Like:
1) [Nature(Intelligence)]: Check the plant to see if you recognise it before you answer her. >>failed roll>> [Nature(Wisdom)]: Observe the plant and see what it tells you about itself before you answer her.
2) “Okay, do your plant thing, I'm ready!”
3) “I don't trust your plant thing, hands off!”
4) [Draw your weapon and attack] (Because this is a Larian game...)
Also a little offtopic ...
Is it just me or do you see
"4) [Draw your weapon and attack]" as something bad? O_o
Bcs honestly i love it ... and i would like to see that option in every conversation (especialy with Astarion).