Dear Joe, I'm not a rain lily expert. Most of them aren't happy in my climate although I found that Zephyranthes candida growing in the same pot with my Meyer lemon and getting drip irrigation every day and citrus fertilizer is finally in its element. It has been in flower for more than 3 months now. I've looked through my archives to see what I could find on Z. citrina. There is this from Paul Niemi in a post about this genus: "Yellow is very common as well, being represented by Z. pulchella, Z. reginae, Z. citrina, forms of Z. katherinae, Z. smallii, Z. jonesii, Z. flavissima and others. Interestingly, the majority of the yellow species are prone to be either apomictic or parthenogenic (older terms that may have been replaced by more modern terminology) tendencies and will generally reproduce true-to-type regardless of what pollen is applied to the stigma." Paul Tyerman asked for the difference between Z. flavissima and Z. citrina and Paul Niemi responded with this: "Z. flavissima is closely related to Z. candida, Z. minima and Z. stellaris (these 4 are sometimes grouped in the subgenus 'Argyropsis'). Side by side Z. flavissima and Z. citrina are easily discernable. The former probably (under ideal conditions) has a longer bloom season with smaller flowers and a very small & delicate stigma. It clumps more readily than does Z. citrina, has narrower foliage with a brighter green color (more akin to the foliage of Z. candida) and prefers moister, even waterlogged conditions; it is also at times reluctant to set seed. Z. citrina is a larger plant with considerably larger bulbs, slower to offset, very adept at setting seed with larger flowers and it prefers dryer conditions and it tends to bloom later in the season. There is some difference in flower color but I don't believe it is a drastic color. Z. flavissima is much more difficult to locate whereas Z. citrina is found everywhere. Plants called Z. citrina were also called Z. sulphurea, but that doesn't appear to be a valid name. A number of people were selling something they called Z. citrina in 2000. I don't know if any of this will help answer your question. Mary Sue