There is, it turns out, no very firm divide between the plant and animal "kingdoms."
One of the big differences is supposed to be mobility. Plants may move their leaves and flowers about over time, but they are rooted in one spot, and that one spot is where their nutrition comes from: right?
Not necessarily. The BBC recently posted footage of a bramble crawling through a forest. Of course, it's time lapse footage, because the crawl is too slow for our unaided eyes to recognize it as such. But it is decidedly crawling.
Brambles re-root easily wherever their tips contact soil, or rotting tree trunk or the like, and that is part of the crawling process as displayed in this footage.
This suggests a more philosophical question: can the bramble feel pain? Might it have some level of consciousness? Is it perhaps making decisions about where it should crawl? "Hey, the soil over there toward the clearing looks better...."
One argument I've encountered for thinking of the animal/plant distinction as a momentous one is this: neither pain nor pleasure nor the conscious desire to avoid the one and pursue the other could do a plant any good. It is rooted in place, after all, come what may.
So, do we call brambles animals?