Yes. Not all poisonous plants will have features to tell you they are, though...

[Fukami frowns. Better to be careful, in that case. He eventually shakes his head.]

We're at a disadvantage. We don't have much we can consult for information on what lives here, plant or creature. [His tentacles have set to pouring up the tea and leaving it to steep now, without him even needing to look.]