Well i am on winter vacation, spending time with my parents. we were talking about the citrus trees we had at our old house in southern California. we had a Meyer lemon and an orange of unknown verity. My mother said they bought the tree from a nursery and it was suppose to be an experimental orange released from the University of Riverside. She thinks they planted it sometime before my birth 1975 and we moved away from that house in 1992. In all that time there were very few oranges ever produced, most years none. My mother thinks the name was Navel of Valencia, suppose to be Valencia without seeds.

Now that I know a little more about citrus I think this tree was from a seed because of the upright growth habit and the few oranges it did have were on the upper part of the tree.

any one what to suggest an id for this verity. I know this is not much to go off of.

Well,
with only names and seeds you could not get the glimpse of a guess.

Because seeds come less or more in abesence or presents of pollinator trees and on climatic environment.
So experimental trees... I would give you the tipp to call the University of Riverside and especially the Riverside Varieties Collection.
Maybe they could be of assist, to give guess of what varieties the tree might have been

Steve, It's going to seem like I'm just arguing with you today, and that is not my intent. But I do think some clarification is needed here. In many varieties, especially the mandarins and their hybrids, the presence or absence of cross-pollination may have a large effect on seed number. But that's generally not the case in sweet oranges. I suppose there may be some small effect (6 seeds vs. 4 in a 'Valencia' for example), but really the seediness level of an orange is genetically determined, so such things as Navels, 'Hamlin', 'Valencia', etc., inherently have small seed counts, while things such as 'Pineapple' and 'Parson Brown' have inherently high seed counts.

Indoors, lack of even self-pollination could have an effect here, but in an outdoor-grown tree, I'm assuming that there are enough bees and other insects to rule that out.

Malcolm