While there are certainly plants that are sustained by the blood of other creatures and some that can even catch their own food, most are of a size that isn't even a threat to your toe, let alone an entire person. You'll note there, I said MOST.
Name: Ya-Te-Veo, Bloodoak, Man-Eating Tree
Size: Being plants, size varies, but most are at least the size which would be required to catch and kill a human being and grow to well above that size.
Appearance: The Ya-Te-Veo has a short, thick, trunk, and dozens of long, tendril-like branches or vines with which it grabs prey. Other reported plants include giant versions of the Venus Fly-Trap and some species of cacti.
Threat: Medium. While any of these plants could be extremely dangerous to the unaware or even to people who don't take the correct precautions, they remain plants. They're not going to uproot and chase you. Probably.
Fortunately, you're not likely to stumble across one of these plants unless you're deep in the uncharted jungles of the Amazon or the Congo. The fact that they are plants means they can't exactly hide in plain sight like an animal could by staying light on its feet and fleeing at the first unfamiliar sound or smell.
As I've said, it is still a fact that there are plants which consume meat. Venus Fly-Traps, Pitcher Plants, and Sundews are all well-known plants that catch and eat insects, small birds, and even mice and rats if the plant grows big enough. No plants are reliably known to grow big enough to prey upon larger animals than that though. I have seen it suggested that some species of cacti use the scent of their flowers to lure animals close enough to impale themselves on the thorns, thus watering the plant with their blood, or in extreme cases, causing them to collapse at the base of the plant, dying and fertilizing the ground with their rotting corpse, but these stories have never been confirmed.
Is there anything to really substantiate any of these stories besides the fact that plants do eat meat on a smaller scale? Not really. Reports of such plants such as in the picture above have been determined to be hoaxes or anecdotal reports. Granted there are several trees which would look like the ones described. Willow trees, with their long, whip-like branches would be easy candidates for trees that are reported to have the long, thin tendrils to grab people with. A small monkey or other animal hiding unseen, shaking branches trying to scare away intruders could certainly give the impression that the tree was actively moving in search of prey.
Of course, killer plants have been used for monsters and plot devices many times over the years. Some well-known movies were books first, which includes The Ruins, and The Day of the Triffids. Movies are much more abundant, with films like Attack of the Killer Tomatoes, Little Shop of Horrors, The Happening, and the movie versions of the two books I just mentioned. They also happen to be fairly common adversaries in video games.
Still, it never hurts to watch your fingers when you go to water your plants. They might be thirsting for something a little more...red.