The original name is Feijoa sellowiana, with Feijoa honoring the Portuguese naturalist João da Silva Feijó and sellowiana honoring the German botanist Friedrich Sellow. More recently, the classification was changed to Acca sellowiana, but the name Feijoa is accepted and used worldwide. It’s definitely shorter than Pineapple guava.
There exist multiple cultivars, many bred in New Zealand and Australia (feijoa is very popular there, especially in NZ) and some in California. I have 12 different cultivars, many purchased about a year ago from Patrick Schafer, who is a well known feijoa enthusiast in Northern California. All his trees are grafted to seedlings, so grafting feijoas is a viable approach for an experienced horticulturalist.
This year I had fruit from Mammoth (2nd harvest), Nikita, Flavia, and Nazemetz (all 1st harvest). I like the flavor of Mammoth and Flavia more than that of Nazemetz, and also the fruits of Mammoth and especially Flavia are quite larger. However, fruit quality in first few harvests might be not characteristic, so I will hold my judgement until I have more experience.
All my feijoa trees are on drip irrigation during the dry season (approximately April to October), and the irrigation is turned off during the wet season. This year, rains in Nor. Cal. started in late September, which is about a month earlier than usual. This year, I picked the fruit from Oct 23 to Nov 18. I only pick the feijoa fruit when it’s fully ripe, i.e., it when it falls from the tree. Fruits can be eaten right after they’re picked from under the tree or kept in a refrigerator for a few days. I eat them in the same way I eat kiwi fruit — cut in half along a longer axis and scoop the flesh with a spoon.