This must surely be one of the most intimidating of all plants - the Paper-spined Cholla Tephrocactus articulatus var. papyracanthus. It comes from Argentina and those sabre-shaped spines that look so lethal are about eight centimetres long, but they're not as dangerous as they look. They really are like paper and simply bend under the slightest pressure; you'd be hard-put to draw blood with them. The tufts of tiny bristle-like hairs called glochids that you can see at their base are far more of a problem. They have barbed tips and are intensely irritating when they embed themselves in your fingers.The easiest way to remove them from flesh is to use a piece of adhesvive tape to pull them out.
Paper-spine cholla ( or the 'Edward Scissorhands' cactus, as my kids used to call it) is a slow-growing relative of the prickly pear cactus and is easily propagated by breaking off one of the jointed stem segments and rooting it in well-drained, gritty compost - but be sure to watch out for those nasty little glochids.