Brazil nut tree flower

The botany of Christmas

Plants play an important role in the meaning and enjoyment of midwinter celebrations – whether in the shining green foliage used for decoration, the frankincense and myrrh of the Bible stories or the ingredients of festive food and drink.

For home bakers, Christmas is a time of manic activity. That is when really special treats are made – rich fruitcake, mince pies, and Christmas puddings.

Traditional in Germany are spiced biscuits and the stollen sweet bread with marzipan centre. Epiphany is also celebrated in many countries on January 6 and in Spain with parades and presents for the children. Portugal has delicious Bolo-Rei cake with crystallised fruits. Traditional recipes include a large fava bean – whoever finds that pays for the cake next year.

Typical spices associated with Christmas include cinnamon, cloves and ginger and their rich smells bring the season vividly to mind at any time of year. Spices were too expensive to use frequently, so they were saved for special occasions.

First performed in St Petersburg in 1892, The Nutcracker is now a Christmas stalwart. Whilst it was unlikely to have been Tchaikovsky’s intention, Act Two devotes significant time to economic botany. The dancers reflect the countries of origin for key crops, most obviously Chinese dancers for tea and Arabian for coffee.

Russian dancers for candy canes illustrate that, in the 19th century, sugar from beet was cheaper than imported cane sugar, and Spanish dancers for chocolate reflect its origins in Spain’s American empire. The famous Waltz of the Flowers, the gingerbread mother and even the reed flutes might all be linked to economic botany.

The botany of Christmas nuts deserves some scrutiny. Nuts are a good source of protein and contain many vitamins, minerals and healthy fats.

Sweet chestnut, Castanea sativa, is a wind-pollinated, deciduous tree native to southern Europe. Three chestnuts grow inside each prickly husk. Chestnuts are used to make the traditional Italian dessert ‘Dolci al Cucchiaio’ and the Russian pudding ‘Nesselrode’. Street vendors selling roast chestnuts are a common sight throughout Portugal during the winter.

Sweet chestnuts and oak acorns were a staple of the ancient diet before wheat. In Italy, large ancient, coppiced trees are sometimes divided between owners to maximise the valuable crop.

Brazil nuts are my favourite from a botanical perspective. Brazil nuts, Bertholletia excelsis, are in the Lecythidaceae family. The Brazil nut tree grows to 50m and reputedly to 1,000 years old in tropical rainforests in the Amazon basin and across Guiana. The large yellow flowers can only be pollinated by a bee large enough to lift the flower hood and with tongues long enough to negotiate the complex shape. Such bees require access to the rainforest for survival.

The small male of the bee Eulaema mocsaryi obtains fragrances essential for mating from the rainforest orchid Cattleya eldorado. The large, long-tongued female bee is the pollinator, so both orchids and bees are required for pollination.

The resulting fruit is a large capsule taking 14 months to mature and weighing up to 2kg. Each fruit contains 8-24 Brazil nuts packed something like the segments of an orange. The complexity of the Brazil nut tree’s ecology means that they are essentially still sourced from wild trees rather than plantations, hence their cost.

Hazelnuts, Corylus avellana, are native to Europe and Western Asia and are now included in the Betulaceae or Birch family. Hazelnut trees are deciduous and flower in wind-pollinated catkins. Hazelnut trees can grow to 10m but are more familiar in European hedgerows. Most of the world’s current production is from Turkey.

Very popular here in Portugal is the common walnut, Juglans regia. The walnut is native in Turkey through central Asia as far as southwestern China. The famed walnut forests of Kyrgyzstan see walnut trees growing to 35m with a trunk up to 2m in diameter in almost pure stands up to 1,000 years old. Walnut trees are valued for their timber as well as their nuts.

The walnut, like the almond and olive, is a drupe, as the nut is encased in a fleshy, green husk. Walnuts and other nuts make a great snack to have with your glass of port.

If you want to grow almond, hazel or walnut, pollination is an important issue. They are effectively self-incompatible meaning a single tree won’t be sufficient for fruit production – another variety is required for cross pollination.

The gifts brought by the Three Wise Men are celebrated as part of Christmas, and they have an interesting story of their own. The value of frankincense and myrrh exceeded that of gold in Roman times, so the gifts were indeed very precious.

Over 3,000 tonnes of frankincense were exported by camel caravans along the incense trail and frankincense was as important in Roman times to the economy of Arabia as oil is today. The value of frankincense is apparent from the security employed in ancient Egyptian perfume factories.

Theophrastus observed, “No security is good enough. A seal is affixed to the workmen’s loins; they have to wear a mask or hairnet with a close mesh; when they finish work, they are strip searched.” We can only hope the wages were good!

While frankincense was usually burnt to produce incense, myrrh was more often dissolved in oil and used as a perfume and medicine, especially as a salve for wounds and sores.

Frankincense and myrrh are small trees with distinctive smooth, peeling or flaking bark. Both are placed in the Burseraceae family, characterised by non-allergenic resins and are native to northeast Africa and the Arabian Peninsula. Both bleed a latex when cut, trees are tapped in the wild and dried resin collected for sale.

The botanical name for frankincense is Boswellia sacra, a species native to Saudi Arabia and Somalia and probably the original balsam brought from the Land of Punt for the Queen of Sheba.

Myrrh is Commiphora myrrha, although Biblical myrrh was Commiphora guidotii, a species native to Somalia and Ethiopia. The scented resins from these species are still largely collected from wild trees and remain precious due to their rarity, starkly illustrated by their near-threatened conservation status.

Enjoy your traditional festive dishes, but remember we are no less dependent on the plant kingdom for our midwinter celebrations than at any other time of the year.

Boas Festas!

By Rosie Peddle
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Rainforest orchid, Cattleya eldorado
Mixed nuts
Frank (left); Myrrh (right
Eulaema polychroma
Commiphora myrrha buds
Christmas cookies
Christmas cake
Brazil nut
Brazil nut tree flower
Brazil nut pod containing shelled Brazil nuts
Boswellia sacra