There is a widely-held belief that it was Portuguese traders who first brought the “sweet orange” to Europe from Asia (some say India, others say China) in the early 16th century. For 500 years prior to this, it was the bitter Persian orange that was grown in Southern Europe.

The story goes that it was the Portuguese explorer Vasco de Gama who brought the root of an orange tree from China to Portugal, and that all the oranges of Portugal, Spain and France are descendents of that single tree, still preserved in Lisbon. What is more likely is that Portuguese sailors and merchants brought back orange tree plants and seeds from their travels to plant in their own gardens.

It is known that Portugal is responsible for the deliberate introduction of the orange tree to the southern states of the USA and to Brazil - two of the largest present-day exporters of oranges.

Interestingly, many languages in and around Europe have coined different words for the bitter and the sweet orange, and in many cases the word for the sweet orange is almost synonymous with that country’s word for Portugal!

For example:

Greece – portokali   (πορτοκάλι) - Portugal is Portogalia (Πορτογαλλία)  
Persian – porteghal
Turkish – portakal
Bulgarian – portokal (портокал)

Arabic -  برتقال (burtuqaal) there is no "p" in Arabic, and it usually becomes a "b"  in borrowed foreign words. The word for "Portugal" is البرتغال (al-burtughaal)

In Brescia, northern Italy the word "portugai" is used in reference to some kind of fruits, from people speaking dialect.

However, the English word “orange” derives from the Sanskrit nāraṅgaḥ  "orange tree" from which also comes the Portuguese word for orange – “laranja”. It is from this root that many other languages have created their word for the bitter orange.

This was a short-lived skirmish that took place in 1801, when France and Spain took up arms against Portugal. The year before, Napoleon Bonaparte had demanded of Portugal, who had been an ally of Britain since the Treaty of 1373, that she enter into an alliance with France in the war against Britain, and hand over a large part of her territory to France in the process.

Portugal wisely refused, and in April 1801 French troops arrived in Portugal, soon to be supported by the Spanish. Unfortunately, the Portuguese were defeated in a battle at Olivença, near the Spanish frontier. Afterwards, the Spanish general Godoy picked oranges at the nearby town of Elvas and sent them to the Queen of Spain with news of his victory. Henceforth, the conflict was known as the War of the Oranges!

In the village of Ponte de Sotão, during World War II, the Germans (with the support of Salazar, who was pro-Nazi) set up a small factory inside a house to produce kerosene from the local orange peel.
The hydrocarbon d/limonene, contained in the orange peel, was extracted by heating large quantities of orange peel, then distilling the oil. The oil has similar properties to benzene.
We know that the building was demolished and the equipment sold during WWII, so we can presume from this that the exercise was not viable.

The d/limonene molecule

It was the Moors who first brought lemons to Portugal, during their conquest of the Iberian peninsular. By the 13th century lemons were well established in the country.

Once it was realised that it was the absence of fresh fruit in the diet (specifically Vitamin C as we know today) that caused scurvy in sailors, it was found that lemons could counteract this deficiency. So Portuguese sailors travelling the globe took lemons with them, and from their seeds lemon trees took root around the world.

In the 21st century it is the Lisbon lemon, introduced from Portugal, that is one of the three main varieties of lemon grown in Australian homes, and it is also a major US variety. Increasingly, it is being discovered that lemons have numerous beneficial properties, including phytochemicals – plant compounds that can help fight cancer and heart disease.

Maybe the courtesans at the Parisian court of Louis XIV were on to a good thing when they “took receipt of sweet oranges and lemons” from Portugal?
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Around the Góis region you will find orange, tangerine and lemon trees growing. Even in the mountains, villages at altitudes of 800m and more still have large productive orange trees with sweet fruit. But beware! When walking through a mountain village in March, I passed a large orange tree spectacularly hung with hundreds of ripe oranges. I made the mistake of reaching up to pick a single fruit. Not being familiar with picking oranges I merely pulled at it, thus bringing down, as the branch re-bounded, a hundred or so more. Worse was to come – I realised that the owner, a robust Portuguese lady, was standing a short way from her tree. . .