Whether we’ve seen them with our own eyes, or in TV, film or video vistas, we’re all familiar with orange groves, those seemingly endless rows of orange trees ready to yield their fruit to the produce aisles or chilled juice sections of your local grocery store.
But orange trees — most commonly Citrus sinensis, the sweet orange — also are cultivated in other places. They’ll often appear in home landscapes, both for their appearance and their fruit.
Read on, and you’ll learn how to identify an orange tree — a whole range of orange trees, in fact — from nothing more than leaves and other non-edible clues.
Where to Find Sweet Orange Trees
Researching its growth range is a good way to start narrowing down the questions around how to identify an orange tree, and whether what you’re looking at is, in fact, a sweet orange tree.
Based on data from the US Department of Agriculture’s plant hardiness map, sweet orange trees will thrive in California, across southern Arizona, into southern Texas and southern Louisiana, and along the Florida peninsula.
But with careful tending, sweet orange trees can grow as far north as Oregon and Washington, through the middle of Texas, across southern Louisiana and northern Arkansas, through wide swaths of Mississippi and Alabama and across most of Georgia into South Carolina and North Carolina.
Anywhere outside of that range, and what you’re looking at likely is not a sweet orange tree.
Orange Tree Identification Starts With Size and Shape
So, how do you know whether you or your neighbor might have an orange tree growing in the yard, even when no fruit is growing on it?
As with most trees, it’s easiest for the average person learning how to identify an orange tree to identify a specimen when it has matured. At that stage, the tree is providing the widest variety of clues regarding its identity, although some of those clues will appear only on a seasonal basis.
A mature orange tree will range anywhere from 25 feet to as much as 50 feet tall. Height can, however, be somewhat misleading in terms of identifying a sweet orange tree.
If the sweet orange tree in your neighbor’s yard was purchased from a nursery, it most likely is a grafted specimen with a dwarf rootstock, meaning that it likely won’t grow any more than 15 feet tall.
As you get closer to the tree you’re investigating, pay particular attention to its newer branches, which will be noticeably twisted.
An additional branch-related clue for how to identify an orange tree can be found in the top of the tree. Specifically, the crown of the sweet orange tree will be defined by slender branches arrayed in a rounded shape.
Buds Help in How to Identify an Orange Tree
Before an orange tree blossoms with the flowers that have a chance to transform into oranges, it will produce small white buds, beginning in late winter or early spring.
About the size of a pea, the buds form in small groups on shoots radiating from the tree’s main branches.
Buds will transform into flowers when the temperature stays consistently at 55 degrees or above. On the opposite end of the temperature scale, however, buds can be damaged if they are present when the temperature drops to 27 degrees or lower.
Flowers and Leaves in Orange Tree Identification
One helpful fact when you’re trying to determine whether you’ve located an orange tree is that its leaves are evergreen, providing a year-round means of how to identify an orange tree.
As you take a more detailed look at your tree’s leaves, take special note of their size and shape. A sweet orange tree will have oval-shaped leaves that can be as much as 6 inches long. Other orange trees also will have oval-shaped leaves, but there are variations depending on the tree species.
At its blooming, a sweet orange tree will display tiny white flowers, about 2 inches wide, either singly or in groups of two to six blossoms. The blossoms will have a fresh, clean scent sometimes described as “baby-like.” The scent is strong enough to waft on the breeze, giving a clue in orange tree identification from some distance away from the actual tree.
Calyces and Stamens Help in Identifying Orange Trees
Delving into more detail regarding how to identify an orange tree, take a look at the green area below the blossom, the part that holds the flower in place. That area, known as a calyx — the plural is calyces — will have five points within which the flower rests.
The points of the calyx correspond to the five petals in the orange tree blossom. Each of the five petals in the blossom are oblong, and each blossomed flower will have about two dozen stamens at its center. The stamens produce the pollen that reaches other blooms to produce oranges.
Atop each stamen, you’ll find a yellow-colored anther, the part of the stamen in which the orange tree flower’s pollen is held, and yet another element of orange tree identification.
A Quick Note on Pollination of Sweet Orange Trees
As another boost to your orange tree knowledge, albeit one that might not be much help in how to identify an orange tree, is that most orange trees are self-pollinating. That means the pollen is transferred among blooms on a single tree by wandering insects or even puffs of wind, ultimately leading to fruit formation.
Interestingly, only about 1% of the flowers on an orange tree will survive to be pollinated and form fruit. Most of the flowers simply will fall off the tree before pollination occurs.
How to Identify an Orange Tree by its Bark
A healthy orange tree will have a grayish-brown tint in the bark along its trunk. Unfortunately for the tree, it may also sometimes be identified by cracks in the bark on its trunk.
Those cracks can signify the presence of disease — likely either gummosis, a fungal disease, or psorosis, a citrus tree disease caused by a number of viruses.
Gummosis can be prevented by taking care not to cause injury to the bark in the first place.
Psorosis, which occurs mostly in trees that have been grafted with a shoot from another tree, can be treated by scraping away infected bark.
That’s not likely to be effective, though, according to experts, meaning that it’s best just to remove the tree from the landscape if it is showing signs of psorosis infestation.
How to Identify the Mandarin Orange Tree
In the world of oranges, “mandarin” denotes an entire group of small oranges. In addition to mandarins, the group includes satsumas, clementines and tangerines.
In general, these trees — with mandarins, clementines and tangerines in the species Citrus reticulata and satsumas designated as Citrus unshiu — can grow to a mature height of about 25 feet.
The various varieties of mandarin orange trees generally are characterized by long and slender branches. Beyond that, though, specific ways of how to identify an orange tree among the mandarin species can get a little tricky.
For instance, depending on the species, some of these species of orange trees will grow with an erect stance, while others will have a drooping growth pattern, potentially creating some confusion in orange tree identification.
Additionally, while all of the various types of mandarin orange trees have leaves that grow in a lanceolate pattern — narrow ovals tapering to a point at each end — some have toothed edges while others do not.
Also, some trees within these species have leaves with hairs, as a protection against insects, while others do not, again creating some possible confusion in orange tree identification.
How to Identify the Blood Orange Tree
Like the sweet orange tree, the blood orange tree is part of the Citrus sinensis species. Its growth range, again like the sweet orange tree, comprises California, across southern Arizona into southern Texas and southern Louisiana, and along the Florida peninsula.
The blood orange tree is similar in appearance to the sweet orange tree, but it grows only to about 12 to 15 feet in height, half or less of the height of the sweet orange tree and a good clue .
Using Fruit in Orange Tree Identification
The easiest fruit-based determination of how to identify an orange tree is found with the blood orange tree. An initial clue, when the tree is bearing fruit, is that the rind of a blood orange tree occasionally will feature a red spot not present on the rinds of other oranges.
But even before you peel a blood orange, there’s a way to tell if that is, in fact, what you’re seeing. On the tree, blood oranges grow in clusters often containing three or more of the fruits.
Then, when peeled, the blood orange reveals the blood-red color the gives the fruit its name. That coloration is due to the presence of anthocyanin, a pigment which forms in the blood orange when the growing season moves into warm days balanced with cooler nights.
And even if the color isn’t enough to tip you off to the fact that you’ve found a blood orange tree, the taste of the fruit — the familiar orange flavor, but tinged with a noticeable touch of raspberry — will make the definitive case that you’ve found a blood orange tree in your quest for orange tree identification.
In a different way, the fruit produced by a mandarin orange tree will differentiate it from the sweet orange. The mandaring orange has a looser skin than other oranges, making it noticeably easier to peel and providing a hint in orange tree identification.
Also when you peel a mandarin orange, you’ll notice a net-like pattern in the white underside of the peel. That pattern, called a reticulated design, is what gives the mandarin orange its scientific name of Citrus reticulata.
Easiest to identify among the various orange trees is, of course, the fruit of the sweet orange tree.
But while the bright orange orbs produced by sweet orange trees are very familiar, there are some interesting facts about the fruit. Sweet oranges are a great source of potassium, which may guard against high blood pressure, and they contain citrate, which might keep kidney stones from forming.
Never Guess About an Orange Tree Again!
We hope that this post has given you the horticultural confidence to declare that you can, in fact, unfailingly identify an orange tree, regardless of whether it has fruit growing on it or not.
Excited for more orange content? Check out our orange trees page to start learning everything there is to know about your favorite citrus!