haha I usually have about 20 or so things that bloom yellow. I got tired of yellow when I first moved here, but now I like yellow flowers. My Parkinsonia (Palo Verde) have yellow blooms and this year they were amazing. The P. microphylla in the front that started out as nothing but a tiny little twig has grow taller and this year was finally covered with thousands of little yellow flowers. (it even caused an accident, a bee flew into a guys window and he crashed his van right down the street from me, where was the bee going? to my Palo Verde tree)
I do like other colored flowers tho.
Those Grusonia sure show you that they are related to Opuntia/Cylindropuntia...
It looks almost like a Cylindro flower.
Here's to you, all you insidious creatures of green..er I mean cacti.