Prickly Pear Cactus Opuntia vulgarisLess spiky than other cacti! This unique cactus (Opuntia vulgaris), is really something unique to bring into your household. This houseplant has a sturdy appearance and has no spines. The cactus has few requirements. We provide a nice bright place in the house. Like other cacti, a lot of water is not necessary. We water about once a month. For the greenest living rooms!