Sheep farmers needn't worry about a menacing plant at RHS Wisley attacking their sheep! First, read the original story here: http://www.bbc.co.uk/news/uk-england-surrey-22967160
Puyas are terrestrial bromeliads native to fairly arid areas of South America, with most originating from the Andes. They are notorious in specialist gardening circles for their stiff and vicious backward facing spines that can easily ensnare an unsuspecting hand. Interestingly Puya raimondi holds the record for the tallest flower spike of any plant, a staggering 32ft (10m) tall!
But are they carnivorous? Despite disagreements from anyone who has lost their own blood to this genus, they are not. Carnivorous plants are specifically adapted to lure in their prey, usually with the promise of tasty nectar, but then trap the prey in sticky goo (e.g. Drosera), pitfall traps (e.g. Sarrecenia) or in a fast moving trap (e.g. Dionaea, the Venus' Fly Trap). There are a couple of disputed carnivorous bromeliads too, Catopsis and Brocchinia, but these are epiphytic 'tank' bromeliads and are very different from Puyas.
Stories about Puyas feasting on sheep are probably exaggerated- no doubt sheep occasionally get trapped in the huge rosettes of Puyas, and cuts to the face from the sharp spines are probably fairly commonplace (after all sheep aren't all that bright!) but there's nothing really to suggest that the Puyas are munching on fresh lamb!
I originally saw this story in the members magazine of the Eden Project in Cornwall, although it might have come second hand to them. As my friend showed me the article I was astonished to read these claims of carnivory being peddled by a so-called educational establishment. To find this dubious information being passed on by the RHS is doubly disappointing, but I suppose the promise of a rare and macabre plant will do no end of good to their visitor figures, but there's one thing puzzling me; Puya chilensis is a rare plant with vicious spines that seldom flowers outside the mild gardens of Cornwall, but when it does it produces a flower spike 10ft (3m) tall... why isn't that impressive on it's own?!