I was working on an automated Kekimurus using a simple system that I also used for my Endoflames when I noticed that the Rannuncarpus won't grab an item that's on a wooden pressure plate. Further investigation shows that the same holds true for any pressure plate that is pressed down, even a stone one if the player can't pick up the item on it. The stone pressure plate leads me to believe that this is a bug.

I'm not sure if this is intended or not. If it was intended then I feel that such an important thing should be mentioned in the Rannuncarpus's Lexica Botania entry and if it's not intended then it needs fixing.

Is the said pressure plate placed on the side of the plant?

Yes, you're right. It looks like it only does this while the pressure plate is next to it.

Fyi, plants are disabled by redstone signals.

I see now. This isn't an issue then, I'll close this. My bad.

💯

Specifically, plants that use a redstone root in their crafting (and the orechid in Garden of Glass) turn off with a redstone signal.