Citrus fruits are available in countless varieties. While they have their origin in Southeast Asia, they are today grown in all subtropical regions, such as the southern United States, the Mediterranean, and South Africa. They were popularized in the British Royal Navy in the 19th century to fight off scurvy.

Yuzu is popular in Japan and has a wonderful, slightly perfumy flavor something like a lime or kumquat but different from both. The limes available in equatorial countries such as Thailand and Malaysia are even more fragrant than ordinary limes that you can get in supermarkets in temperate countries.

Meyer lemons are widely praised for the taste of both their flesh and zest. They are native to China but their trees were grown mostly for their beauty. They are now widely grown and used for food or as a garnish in many dishes and drinks.

The pomelo, kind of like a large, sweet, not-very-juicy grapefruit, is harvested in autumn in China. The area around Ipoh, Malaysia is also famous for its pomelos.

Bilberries, lingonberries, cloudberries and cranberries are among the few fruits available in boreal climates, and common in Nordic cuisine. Other berries, including strawberries, raspberries, blackberries and blueberries, grow wild on hillsides and other temperate areas. The wild berries are the tastiest kinds, packing a lot of flavor in a very small package, as wild strawberries, for example, are much smaller than some cultivated varieties.

In the summer in Guangdong province of China and some other areas where they are grown, try lychees. They are exported long distances nowadays but taste best close to where they are grown. They have a unique sweet, perfumy taste with sometimes just a hint of tartness. The best ones usually have red skins, but a bit of brown in the skin is not necessarily a problem, if you don't wait too long to eat them. Similar fruits grown in the same area include wampees (yellow skin, grape-shaped, and tart) and longans (small with light brown skin, may be available year-round).

The Big Island of Hawaii has some unique fruits which do not grow anywhere else. In particular, poha berries are plentiful there and have a uniquely delicious taste.

When you are in California, especially Central or Southern California, make sure to try some ripe avocados. Mexico is also known for avocados, which are native to the country. Outside of avocado-growing areas, you may struggle to find avocados that are ripe and of good quality. Guacamole, a sauce based on avocados, is a well-known staple of Mexican food, dating back to Aztec times. The avocado is the fattiest fruit in the world except for the durian, but the types of fat in avocados are healthy for most people. Though avocados can be treated as vegetables and are frequently used in salads, they are biologically fruits, and in South America are consumed as such, often smoothied with milk and sugar.

Dates originate in the Middle East but are widely cultivated. They're sweet, come in many varieties, and can be eaten fresh or dried. Saudi Arabia and other Arabian countries are particularly known for their dates, although Medjools, probably the most prized variety, originally come from the oasis of Tafilalt, about 5 km from Rissani in Saharan Morocco.

Umbria is known for its black truffles, which are used with both pastas and meats. Wild mushrooms are gathered in many places. For example, Poland, Germany (such as the Black Forest of Bavaria) and neighboring countries are famous for their wild boletus and chanterelle mushrooms. In Germany, chanterelles are called Pfifferlinge. Look for dishes and soups with them in season, when they are widely available and not very expensive.

Poland, Russia and other countries in the region also traditionally use sheep sorrel, a tangy, tart leaf used in schav, a soup or drink to which sour cream is traditionally added.

Japanese people greatly appreciate seaweeds. In particular, Okinawans have traditionally eaten a great deal of seaweed of various types, with different tastes and textures.

Okra is appreciated in various parts of the world. In Louisiana, it is often used as a thickening agent in gumbo, a spicy soup central to Cajun cuisine. By contrast, in India and Japan, it is pan-fried or broiled, so as to deemphasize its mucilaginous qualities.

Satsuma-imo, also called Japanese sweet potato, is a delicious tuber that is widely enjoyed throughout Japan. Its taste is not as sweet as orange sweet potatoes, but it is also available in candied form. Good, inexpensive candied satsuma-imo can be found at 7-Eleven stores throughout the country, and more delicious, higher-class candied satsuma-imo can be purchased at food courts in the basements of upscale department stores in neighborhoods like Tokyo's Ginza.

The temperate Altiplano of Andean countries like Peru and Bolivia is the wellspring of the potato, which is found in that part of the world in many varieties and colors. Many of the local types of potato are very nutritious.

In Southeast Asia, try mangosteen, rambutan, durian (only for the fearless, as it is very smelly), jambu air (water apple), carambola, salak (a sour fruit also known as snake fruit after its scaly skin), and if you are lucky enough to find it growing wild, buah kemunting (rose myrtle berries, which are small red or purple fruits that grow on a bush). Also have local bananas, which are ripened on the tree and are really entirely different in taste and texture from the varieties that are picked weeks before tree-ripening for export to temperate countries. The huge jackfruit, a fruit of sweet, sticky sections, makes a good treat for vegetarians as it is very meatlike when cooked right, such as in a savory Thai or Malaysian curry.

The sugar-apple, also known as sweetsop, is native to the Americas but cultivated in many countries around the world. Particularly popular in Taiwan, it's a light green fruit whose appearance bears a faint resemblance to an artichoke, but its flesh is white, soft, and very sweet, with lots of big, hard, black seeds.

The red or pink wax apple, native to Southeast Asia, looks a bit like a pear-shaped pepper. It's softer than an apple but similarly refreshing and light in flavor.

In South America, Hawaii and elsewhere, try passionfruit (called lilikoi in Hawaii).

Pineapples are widely cultivated and shipped far and wide, but fresh pineapple in an area where it grows is deliciously sweet and juicy and a far cry from anything you'll find in a can.

If you've ever enjoyed mango, don't miss a chance to try it in an area where it grows. The larger varieties that are more widely available in mango-growing countries are juicier and more delicious than the one smaller, oblong variety that exports best. In particular, the Indian Subcontinent is famous for its alphonso mangoes, but it's also typical for a few varieties to be grown in Southeast Asian countries.

The jujube, also known as the Chinese date or red date, is a smallish fruit, similar to an apple in taste and texture and popular in parts of Asia.

Water spinach, also called kangkung or ong choy, is popular throughout Southern China and Southeast Asia. It's a dark green leafy vegetable, like spinach or other greens, but distinguishable by its hollow stem.

The deliciously crunchy lotus root is eaten in many parts of South, East and Southeast Asia.

In Malaysia, the young leaves of the cashew tree are eaten. They have a unique, tangy taste but deteriorate very quickly after picking, so they are best eaten right away, such as in salad (ulam in Malay — which is eaten with sambal belacan, a combination of shrimp paste and hot pepper) and cannot be exported.

The coconut is a staple of the tropics around the world, but this sweet, watery nut is highly atypical of nuts.

In Hawaii, make sure to eat macadamia nuts. Even the big brands like Blue Diamond and Dole sell a much better class of macadamia nuts in Hawaii than you can get anywhere else. Fresh macadamia nuts are wonderfully complex and delicious, and most of the flavors don't seem to survive long trips from Hawaii to any other place.

Syria, Iran and Turkey (Southeastern Anatolia in particular) are famous for their great pistachios. Sadly, Syria is not going to be a safe place to travel to any time soon, but the other two countries are open for visitors.

While peanuts aren't nuts in the botanical sense, they have been grouped here because common parlance treats them as nuts. The peanut plant has been grown for thousands of years in Peru, and peanuts form a part of Peruvian cuisine, but the continent where their presence in cuisine is probably most strongly felt is Africa. In West Africa, peanut sauce, peanut butter soup and meat stew with peanuts are frequently found, and East Africans use both peanut sauce and peanut relishes. The peanut is also used to make the spicy peanut sauce in Southeast Asia which is used for satay, a meat-on-skewers dish popular throughout the region; gado-gado, an Indonesian salad; and various other dishes.