the genus rhipsalis contains approx. 40 species. they grow either epiphytic (on trees), epilithic (on rocks) or terrestrial (on the ground). as houseplants they became popular more and more the past years. the mistletoe cactus (rhipsalis baccifera) is developing small white to yellow flowers.
more info about the members of the genus rhipsalis you can find here: rhipsalis.net.