Because there is a citrus tree in almost every yard in California, we often inherit one when we move into a new house. Which kind is it? What if there’s no one around to tell you?

Here I describe how I approached figuring out the identities of a couple mystery citrus trees in my yard and in the yard of my neighbor. My goal is to show how you might discover which kind of citrus tree you have, if you’re in a position like us.

Some kind of orange?

There was a large orange tree in the yard when we moved into our house.

The fruit tasted good right then, in July of 2013. I knew the tree wasn’t a navel because the fruit didn’t have a navel; I figured it was a Valencia because it was ripe in the summer.

But there were two problems. The rind wasn’t as smooth as the Valencias I’d always eaten elsewhere, and the oranges almost never had a seed. I’d always known Valencias to be seedy.

I looked on the University of California, Riverside Citrus Variety Collection’s listing of Valencia-type oranges and found two seedless varieties: Delta and Midknight. The photos and descriptions for both sounded like they could be my tree and its fruit.

Is mine a Midknight Valencia orange?

My best guess today is that mine is a Midknight because that is the only variety that I’ve seen being sold by nurseries to home gardeners. For example, Four Winds Growers sells Midknight Valencia trees here.

Multiple trunks and leaves in threes

Over to my neighbor’s yard. My neighbor has a tree with multiple trunks. That’s always an indicator that at least one of the trunks is rootstock.

Upon a closer look, I saw that all the leaves were in groups of three. That settled it. The whole tree must be some kind of trifoliate rootstock.

Can we figure out which? I went to the UCR CVC Rootstocks page. I knew that two trifoliate rootstocks have been most commonly used for the last couple decades so I went to their pages. Unfortunately, C-35 sounded and looked indistinguishable from Carrizo. So I went to the more detailed pages at Citrus ID. There I found two important clues. C-35 was described as having straight thorns and medium wings on the leaf petioles (stems) whereas Carrizo was described as having thorns that were absent or not persistent and narrow wings on the leaf petioles. This tree had plenty of thorns and the wings on the petioles were medium. This aligned with the tree in question. Therefore, my best guess on this tree is C-35.

Here is the fruit, by the way. It has an odd bitter taste.

(Why does my neighbor have an entire tree of rootstock? Happens to the best of us. See my post, “Beware of rootstock suckers on citrus trees.”)

The mystery tangerine

Back to my yard. Up the hill is an old tree that is half alive, that I’ve never watered, but which still gives us some fruit each year. We’ve always referred to it as “the mystery tangerine tree.”

The fruit is smaller than an orange, and it’s sweet but tangy. There are a zillion kinds of tangerines though. How to narrow down the possibilities? The best first step is to note whether it has seeds. The mystery tangerines do.

That eliminates all of the seedless varieties. Yet there remain many seedy tangerine varieties to choose from. I scanned the mandarin/tangerine listing in the Sunset Western Garden Book for matching descriptions and found a handful of potential varieties.

Then I looked up those varieties on Citrus ID, where each variety has a page they call a “fact sheet.” While perusing the photos and descriptions on those fact sheets, I kept a couple of distinguishing characteristics in mind. My mystery tangerine often has a protruding neck at the stem end. Not all mandarins have that. And my mystery tangerine peels very easily. Not all mandarins do that.

The combination of these allowed me to further eliminate the varieties Fremont, Honey, Kinnow, Afourer/W.Murcott, and Murcott.

When I hit the fact sheet for Dancy, however, the neck quality and the easy peeling quality were both there. I cross-checked with the Dancy tangerine page of the UCR CVC and found everything aligned again.

Over the years I have eaten Dancy tangerines from other trees, one at the Riverside Collection even, which has made me more confident in my guess.

Foster grapefruit?

One final tree in my neighbor’s yard. This tree’s fruit looks like grapefruit except that the fruit’s rind gets deep yellow unlike any grapefruit I’ve seen. The fruit also gets bigger than any grapefruit I know. My neighbor suspected that it might be a grapefruit called Foster.

But when I looked up Foster on the UCR Citrus Variety Collection website, I found that the description didn’t match. There it is called Foster Pink grapefruit because the flesh is tinged pink. However, this fruit is tinged orange. The page also described it as “sweet and tart” yet this fruit was thoroughly sweet. In fact, it was so sweet that I wondered if it were any kind of grapefruit.

A farmer friend clued me in when I shared a piece of the fruit with him and he instantly said, “This is Cocktail.” Are you sure? “This is Cocktail.”

I looked it up when I got home. Bingo! The Cocktail photos and description on the UCR CVC page match perfectly, and it turns out that the variety is a pummelo and mandarin hybrid, which explains its size and flavor.

That’s cheating, you say. Who has a farmer friend that can just call out a citrus variety at first glance? You’re right. That was like cheating. But we have to use whatever sources are on hand.

Sources for citrus ID

Here are some sources that you might find useful when investigating your own trees:

University of California, Riverside Citrus Variety Collection

Citrus ID

Four Winds Growers Nursery

La Verne Nursery

Sunset Western Garden Book (Most libraries have a copy if you don’t have your own.)

By the way, I’m open for suggestions if you think any of my above identifications are wrong. We would be happy to go back to the tasting board and reconsider.

All of my Yard Posts are listed HERE

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