Thanks Lyndal. I must confess I didn't know the leaves are a weed. It appeared around the time the cactus started thriving and producing the buds, so I thought it might be part of the cactus. I also didn't know about the moss. I have another pot with about five different cacti that have long outgrown the container. I have to re-pot them separately and that will be very tricky because one of the cacti has spikes too and they hurt like h*ll. I'm off to Bunnings in the morning. 
