Plants are our cousin eucaryotes, and they've been evolving as long as we animals have and so there is likely to be equivalent information processing complexity to be found in them, we just don't know how to recognize it because it's so different from animal intelligence. There might even be something comparable to animal consciousness, not at the level of an individual plant, but more collectively, even including multiple species, whole ecosystems of plants and fungi together having an awareness and intelligence that can not only rival ours, but even transcend it, having lifespans in the thousands of years.