Frankincense: resin with many stories

The Bible speaks of the Magi, the wise men, bringing gold, frankincense and myrrh as gifts to the infant Jesus - perhaps the origin of today’s tradition of exchanging Christmas presents. Even the name frankincense conjures up a hint of aromatic incense and the romance (no matter how unromantic it might have been) of times past and long-distance trade. Kew's Economic Botany Collection tells many stories of the history of this important commodity.

How did frankincense get to Kew?

There are 140 frankincense specimens in Kew's Economic Botany Collection. Not only do these show an impressive range of colours and textures – this is, after all, a natural product – but they also represent the wide range of contributors to Kew’s collections. For example, the multicoloured lump of gum-resin in the image below was collected by Isaac Bayley Balfour (1853-1922), a botanist now best-known for reforming the Royal Botanic Garden in Edinburgh. In 1880, Balfour leapt at the opportunity – at just two weeks notice - to lead an expedition to the island of Socotra, when the appointed leader dropped out. Having just become Professor at the University of Glasgow, he did not have much spare time. Armed with letters of introduction and a budget of £420 (somewhere between £50,000 and £500,000 in today’s money), Balfour left Britain on 9 January and arrived at Socotra on 11 February, leaving six weeks to explore the island’s botany, zoology and geology.

Isolated in the Indian Ocean, between Oman and Somalia, Socotra has many plants and animals not found elsewhere, including Boswellia ameero. Balfour was the first to assign a botanical name to the tree, based on its local name. Its resin was mainly used locally, with imported frankincense preferred for important purposes such as medicine and rituals.

An ancient mystery

Biblical scholars have plausibly argued that the symbolism of gold, frankincense and myrrh draws on deep traditions of gifts to royalty in the ancient Near East: gold as precious metal, frankincense for incense, and myrrh as anointing oil. Given this, and the large quantities of frankincense that have circulated in trade in the recent past, one might expect to find plenty of it in archaeological samples.

One important role of the Economic Botany Collection is to supply reference samples to researchers. Modern methods of chemical analysis use tiny amounts of resin – about two hundredths of a gram – so destructive sampling (for a good reason) is not a problem. One of the most detailed studies of archaeological resins from ancient Egypt was carried out by Margaret Serpico and Raymond White, using Kew’s reference samples. Egypt is an important case study as it is close to resin-producing areas, and it has long been thought that the terms sntr or ‘ntyw might refer to frankincense. But Serpico and White’s analyses of ancient jars found instead evidence of large quantities of mastic, a resin from Pistacia lentiscus, which is today produced on the island of Chios. Although frankincense resin has been identified at some Egyptian sites, it remains unclear how much was used.

A plant in demand

Frankincense remains widely valued, both for its traditional purposes as incense and medicine, and in the contemporary perfume industry. There is increasing interest in testing its medicinal properties, for example in treating arthritis. 

However, frankincense remains a wild-harvested product, and there is evidence that overharvesting is affecting trees. Detailed ecological studies by Eritrean and Dutch scientists have shown that in the Horn of Africa woodland is being replaced by fields, and that over-tapping of resin from trees greatly reduces seed production, likewise threatening the future of the woodlands. Unfortunately many of the other producer couintries are unstable, a real barrier to better understanding frankincense production, and enabling local communities to harvest and trade it sustainably.

It’s clear that the long journeys of frankincense, whether across a desert two thousand years ago, or to a modern laboratory, have many more tales to tell.