It turns out I have bees visiting my cactus. I never expected to get fruit from my cacti, but I guess that’s what happens when nature takes it’s course. The cactus in this pot is at least 2 separate seed grown plants, with either some large pups from each or a couple of seeds that were delayed in their germination.
There are no other Echinopsis cactus in the neighborhood, so I assume this white flower was pollinated with it’s yellow neighbor.
Both the white and yellow cactus are in the process of blooming again. The white one started to open last night, and the yellow one will probably open tonight or tomorrow. You can see the difference between the two colors before the flower bud opens up, as the next pictures show. The white flowers are preceded by buds with white fluff, and the yellow flowers have buds that are covered in black fluff.
As you can see, there are plenty of flowers coming in the near future. Whatever I’m doing for this cactus (neglect, maybe?), I’m doing it right.