Citrus season is upon us once again, which means we could all use a little brushing up on the most salient differences between a navel and a Valencia — and other less commonly asked questions about this wintertime fruit.

What’s a navel got do with it?

The “navel” of a navel orange is the thing that vaguely resembles a belly button at one end of the fruit. Inside the belly button is a tiny undeveloped fruit — the “twin,” also edible, of the larger fruit.

Best for juicing?

Valencias, which combine sweetness with a high juice content, are generally considered the best for juicing. Navels are sweeter, but contain less juice.

Which is the Biggest?

Pommelo — growing to a size about midway between a softball and a bowling ball, these enormous fruits taste like grapefruit, but less sour.

And the Smallest?

Kumquats — these inch-diameter fruits are sour on the inside, but boast a sweet edible skin.

Ugliest (but sweet on the inside)?

There’s actually a citrus variety called Ugli, which likely qualifies. The fruit, though squat and warty, is delicious, but it is primarily available in Jamaica where it originated.

Which is the Weirdest?

This is subjective of course, but Buddha’s Hand citrus, which suffers from a genetic deformity that makes it look like an octopus, probably claims this prize.

And the Sweetest?

A new variety from Japan known as Sumo — a hybrid between a mandarin and an orange — is allegedly the sweetest citrus in the world. But it isn’t widely available yet. Check here for a list of stores across the country that carry it.

How about the Sourest?

Sour orange — there are many extremely sour varieties of citrus out there, but this is one of the few with a history of cultivation. Sour orange, also known as Seville orange or bitter orange, is traditionally used in orange marmalade; to flavor Belgian witbier; and as a spice and herbal remedy in many parts of the world.

Best for Zest?

The outer peel of any citrus may be scraped off and used as a flavoring agent, though lemons are certainly the most common. As a general rule, the zest will have a touch of the flavor of the fruit, so use your intuition as to which variety will best suit the dish you’re preparing.

Most Eco-Friendly?

Since citrus is only produced in subtropical locales, go with the fruit produced closest to you — Florida citrus for the eastern half of the country and California, Arizona or Texas citrus elsewhere.

Most Cold-Hardy?

A few obscure varieties, such as the citrandarin, tolerate temperatures down to zero degrees Fahrenheit, but it’s mostly fruit that you would only eat if you were stranded on a small desert island in that category. Of the commonly consumed citrus, kumquats, mandarins and Meyer lemons are the most cold-hardy, tolerating temperatures down to around 20 degrees.

Easiest to Grow at Home?

Lemons and limes are arguably the easiest, mainly because they grow as small bushes and are productive even when kept in a pot, allowing you to bring them indoors to a sunny window for winter.

We hope you learned a thing or two. Now you can enjoy a unique shot of Vitamin C any time you’d like. Thanks for playing along.