In past experience I noticed that the first flowers on Poncirus and Poncirus hybrid seedlings tend to be skewed towards staminate flowers, rather than perfect flowers. This is quite evident in 6 trees blooming for the first time this Spring.
However, as I'm presently pollinating about a hundred Poncirus flowers with Meyer lemon pollen it's very apparent there's a pattern to the distribution of perfect and staminate flowers on mature Poncirus. On each flowering twig the first 3, or so flowers at the outer end of the twig are perfect (having both anthers and pistils). The remaining flowers farther back on the twig are almost all staminate (anthers only).
Additionally, the flowers in the intermediate position often show partially developed pistils.
Although I was aware of the two types of flowers previously, I never noticed that the flower position had such a profound influence on the development of flower type. I'm curious if this applies to other Citrus types.

Staminate flower on the right with anthers about a day before dehiscence. Pistil is undeveloped and non-functional. The flower on the left is perfect (complete).

Perfect flower showing prominent pistil, as well as anthers.
It's probably unnecessary to mention that flowers without pistils can provide pollen, but have no chance of developing into fruit themselves.