Hi,
This fruit is sometinng that I got from Helton about 5 years ago as a seed that was supposed to be Myrciaria delicatula. It is now obvious to me that it is not that but is possibly some sort of psidium species.
as you can see in the photos, the fruit is about one inch in diameter, yellow-green when ripe, and has a distinct lemony-guava flavor, sub-acid, and really pretty tasty. Each fruit contains one or two seeds that are around 3/8 inch in diameter and lenticular. The plant blooms in the spring, ant these fruits took around 10 months to ripen.
The plant itself is quite large, and was about 9 ft before i cut it back, with an open and spreading habit.
Does anyone have any Idea as to what it might be?