Without photos it is a fool's errand. If you edit your text, at the bottom should be a button to attach a photo, not Houzz photo; but your photo.

You can just add a comment right in the comments section below and you can attach a picture (click on the camera icon), wait for it to upload and press the submit button. You can post a picture of the tag the citrus tree came with as well.

If you're interfacing with this forum with a phone, you can't leave a picture in the first post. It's a defect in the program. But you can still leave pictures in any subsequent post.

Without a picture, I'm going to list some possibilities: Temple Orange, Tangor, Tangelo

Also some mandarins can be really tangy and almost orange-like, like Shasta Gold.

If you're really sure it's definitely an orange, it could be sour orange (the type used for making marmalade). I'm assuming you have knowledge of different oranges and know for sure it couldn't be a Valencia, perhaps underripe.

Page mandarins can get pretty tangy and almost orange-like inside but don't get that big.

If you can't provide pictures, you're going to have to give us a LOT more detail to rule any of these out.

I just re-read what socalolympia wrote about the photos. It’s true there’s a bug that makes it impossible to post more than 1 photo in the OP msg with the phone. I think my way around that was to post it anyway then “edit” the OP to add the other photos.

Yipee! I finally got it. A huge thank you to all of you in the Citrus forum for your suggestions--mostly for your amazing degree of helpfulness here. I already feel this is a great forum to be in. Sorry though .. it took me so long to get this and respond.

With these few pictures, I hope it can be a little more helpful for the identification of this citrus. I wonder if this variety is a little more resistant to citrus greening than the other varieties. I do appreciate all the input you have for me.

Looks like it has navel, if you leave it longer on the branch, it might be sweeter.

based on the size, I would guess some sort of Satsuma mandarin

I find this site to be useful: http://www.idtools.org/id/citrus/citrusid/index.php 

You can either use a key (choosing attributes that fit your specimen), or click on fact sheets for that you suspect it might be and compare to their pictures and descriptions.

Johnmerr, thanks for the guess. I wish it was a Satsuma mandarin, but the inside of the fruit doesn't look like a mandarin to me (although I'm not 100% sure), but I'm thinking more of a kind of an orange. I did remember when I bought it from the vendor that it was some kind of orange. Wish the label was still here. I don't have the receipt with me any more ... and I also couldn't ask the vendor without any specifics of the purchase. However, I'm thinking to just go ahead to plant it in the Spring. I'm still happy that this citrus is bearing fruit for me so young in age.

Thank you all once again--really appreciate all the help you're offering.

Sunshine, thanks for the suggestion. The other day I tried to get it off, but it won't budge. I guess it's telling me that it's not ready for harvesting yet ... LOL

After you harvest it, cut it from the top side that it is attached to the tree right down the middle to the bottom (vertically) and if it is a Navel orange, you will clearly see it's "navel ". Picture courtesy of Google (Wikimedia Commons)

lucky_cloud I appreciate the link. I'll go and see what I find there and let you all know if anything matches.

Sunshine, what a clever way to find out! Thanks for showing the picture. I'll be sure to do that when it thinks it's ready to be eaten by me :)

By the way, is that your orange you grow? I see you're from Canada. What kind of oranges are you able to grow there?

The picture above is from Google images, I don't have fruiting orange tree, but recently grafted Valencia orange on one of my rootstock trees. I grow Meyer lemon, Meiwa kumquat, Bearss lime, clementine Fina, calamondin and other grafted and seedling citrus trees. So far I have gotten fruit from Meyer lemon, Bearss lime, Meiwa kumquat the rest of them are still young to fruit, need a year or two to grow.

A navel orange is a sport (an accidental variant); it is really an orange within an orange. I don't think I have ever seen an orange, especially navel of the size you say it is.

It's definitely some sort of orange.

It reminds me of a Hamlin.

Sunshine, it's nice that you can grow all of those citrus trees in your planting zone. I'm glad you have a Valencia orange. I used to have one that bore nice fruit for me for a couple of seasons until citrus greening hit us here. That was many years back. The tree is not doing anything now except hanging onto dear life. Other citrus trees that are doing well for me are all my lemons. I also have a couple of Bearss Lemons. They are very heavy producers and now my branches are loaded with fruit almost ready for harvest. I also have a few of the Keiffer Lime. I thought they were very cold sensitive, but it turned out they really weren't affected too much by our Winter here, so I had one of the planted in the ground. It really took off and it's now standing at 10-12ft height.

I grow my trees in containers and in the winter time they come inside my sunroom. Sorry to hear about your Valencia orange tree. If the tree is sick, why don't you dig it out and destroy it? Can it affect your other citrus trees?