Recognizing citrus trees when they have no fruits

It might seem silly, I know (and probably it is). But you will impress your little gardener friends with this pill of botanic knowledge because… who knows how to tell which citrus tree is it without looking at the fruit? Just a few botany freaks.

A bit of botany

Before getting into the little differences among them, it’s good to know that the Citrus genus are a group of little trees (5-10 m), evergreen and with acid fruits native of Asia.

It’s fairly hard to characterize the Citrus genus because they hybridize pretty easily among themselves and this has resulted in numerous edible and non-edible varieties. According to the classification proposed by Mabberley, there are only three natural species, and all varieties are cultivars of these three:

• Citrus medica: It is the cider. Lemon trees (Citrus x limon) are cider hybrids.
• Citrus maxima: This is the pomelo. It’s sometimes misidentified with the grapefruit, which is a hybrid (Citrus x paradisi). Limes (Citrus x aurantifolia), bitter oranges (Citrus x aurantium) and sweet organges (Citrus x sinensis), are Citrus maxima hybrids as well.
• Citrus reticulata: They are the tangerines and such.

Bear in mind that this is a very simplistic explanation, as there are countless varieties and sometimes it’s not clear what species dominates in the hybridization. Besides, there are a few more non-hybrid citrus trees in the wildness.

So… Citrus trees are a crazy, very alike family. Being able to distinguish them requires a trained eye, as the devil in in the details. Madness!

Which are the differences?

Pomelo (Citrus maxima)

• Its leaves are the biggest and broadest.
• The edges are lightly serrated (less than the leaves of the lemon tree).

• The base of the leaf is rounded.
• The petiole has huge, heart shaped wings.

Sweet orange (Citrus x sinensis)

• The leaves are big and broad, but less than in the pomelo.
• The edges are usually entire. Very few times they are lightly serrated.
• The petiole hasn’t got wings or, if it has them, they are very small and narrow. It is articulated where it joins the leaf blade.

Bitter orange (Citrus x aurantium)

• Leaves are very similar to the sweet orange.
• The biggest difference is in the petiole: the bitter orange leaves do have tiny heart shaped wings (smaller than the wings in the pomelo leaves).

• Its flowers have the best and strongest smell : )

Lemon tree (Citrus x limon)

• Its crown is less compact (less “dense”) than the rest.
• Leaves are big and broad, but not as big as the leaves of the pomelo tree.
• Serrated edges.
• The veins are pronounced in both sides of the leaf blade.
• The petiole is not winged (never, ever).
• Some people say that their leaves smell like lemons when you squeeze them, but… again… madness!

Tangerine (Citrus reticulata)

There are no tangerine trees in my garden, so I can’t show you a photo : (

• Leaves are narrower than the others.
• The base and the tip are sharp.
• The petiole hasn’t got wings and it is articulated where it joins the leaf blade.

These are the citrus trees more common where I live, but it’s different in other places. Would you be able to recognize a lime tree? How about a kumquat? I wouldn’t know! (just for now…).

Image credit:

1. Brooke Cagle
2. Ashim D’Silva
3. The rest are my own.