Oh, there are hundreds of cultivars so your best bet is pick a color, find a reputable nursery that specializes in them and pick something.
This is a Calif. seller, he lists on eBay and he is a good seller, I have talked to him several times at the local nursery he sells at as well as the local annual Landscape and Flowers shows.
http://www.epiphyllumworld.com...
Here's another good vendor
http://www.epies.net/
a list of several nurseries
http://www.epiphyllumsociety.o...
