Well I'm not quite sure what ya mean by just a sem. I have cut off a piece of cactus about 4 inch long and 3 inch wide. And over the years it has grown into a nice sized cactus. But don't make the mistake I did. I didnt reinforce the base of the cactus, so when it grew it grew "limbs out from every direction... and now my cactus kinda looks like a huge pile of prickly moss laying on the ground. Still a cactus nonetheless though right?