Caudiciforms: Yellow adenium flower bud with only 4 petals?, 1 by seraphine

seraphine wrote:
Hello,

I thought I'll share this picture of the my yellow adenium flower bud. I got my second yellow adenium plant from Indonesia last week and surprised to see 5 flower buds. Only one flower bud seem to survive though. I saw that it slightly open this morning and surprise to see that this flower only have 4 petals. This is not the first time for me, my "Eye of the Storm" adenium has had a 4 petals flower once before. But that only happened once and it have been producing the normal 5 petals flowers ever since.
Does anybody have any idea or opinion on why/how this 4 petals flower happens?