Month: December 2016

Advent Botany 2016 – Day 15: Carob Santa Is On the Way! — Culham Research Group

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by Megan Lynch Caracoa, a popular carob candy bar from the ’50s – ’80s At this time of year chocolate is imbibed as hot cocoa, eaten as a confection pressed into the shape of Santa or snowmen, and baked into a variety of holiday treats from recipes often passed down within the family. Where does…

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Advent Botany 2016 – Day 14 – Caraway — Culham Research Group

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By Emma (the unconventional gardener) Cooper Caraway, Carum carvi It’s possible to grow up in the UK and never consciously encounter caraway as a spice – I certainly did. And yet this versatile plant adds flavour to meat, fish, and vegetables details. But it’s claim to Christmas fame comes from its ability to make stand-out…

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The Poison Chronicles Festive edition: Poisoner and matchmaker – the joys of mistletoe

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Guest blog by: Laura Cooper

Viscum album spirit collection

Whilst many species of plants are referred to as mistletoe, the icon of Christmas is the European Mistletoe Viscum album. Mistletoe has a varied reputation; it is a symbol of Christmas and druidic ritual, a poisoner and a matchmaker.

The plant itself belongs to the Santalacea or sandalwood family. It is found throughout much of Europe, but in the UK is localized to the central south. V. album lacks its own trunk and instead grows in the crowns of host trees including apple, lime, hawthorn and poplar when its seeds are dispersed by birds smearing the sticky fruit and seed from their beaks onto the bark of the host. V. album is not a true parasite but a hemiparasite. This is because whilst the seedling sends its haustorium from the roots through the bark of the host to induce the host’s xylem vessels to supply it with water and nutrients, V. album makes its own sugars through photosynthesis. A heavy infestation of mistletoe can take over the entire crown of a tree preventing the host photosynthesising and building its own tissue which can lead to the death of the host.

V. album owes its toxicity to large amounts of the alkaloid tyramine throughout the plant, which is also present at lower levels in foods including cheese. As with most toxins, it is the dose that makes the poison, not the chemical. Whilst little research has been done on the effects of consuming V. album, it has been reported that consuming enough of the leaves or berries can result in nausea, abdominal pain, diarrhea and death. However, the well-known risks of mistletoe means poisoning cases are very rare. As the Poison Garden argues, artificial mistletoe is likely more dangerous as a choking hazard to children than live mistletoe is as a poison.

Image result for mistletoe
4 year old Mistletoe seedlings on a branch

Whilst mistletoe is commonly linked with druids, the only account of a druid ceremony involving mistletoe comes from Pliny the Elder. He details a banquet and ritual sacrifice where a druid would climb an oak tree, cut the mistletoe with a golden sickle and drop it into a cloak to prevent it touching the ground and losing its power. The link between druids and mistletoe was picked up in the revival of druidry in the 18th century and today druids carry out a similar ceremony, without the human sacrifice! The tradition of kissing under the mistletoe at Christmas is not a Christian tradition but also derives from the association of mistletoe with fertility in druidic mythology. Christianity has a less favorable relationship with mistletoe, as according to tradition mistletoe wood was used to makes Christ’s cross and ever since could not grow upon the earth so was condemned to parasitic life.

Mistletoe has also been used as a medicine historically, including as an epilepsy treatment. Today, injection of extracts of mistletoe has been used as an anti-cancer treatment in alternative and complementary healthcare. Whilst it has been shown to kill cancer cells, the few trials done were inconclusive or poorly done, and the NHS advises that there is currently no reliable evidence that mistletoe is effective at treating cancer.


For more mistletoe information, see:

#AdventBotany 2016 Day 13: A very festive and minty Christmas with Wintergreen

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Guest blog by: Sophie Mogg (with images and introduction provided by Rachel Webster)

It’s always a joy to see something growing through these dark and dreary winter months. With glossy, green leaves, little cream bell-like flowers and big, red berries that start to appear as the snow melts, today’s plant, Gaultheria procumbens, is a very popular choice for baskets and containers. The name of this plant originates from Pehr Kalm, a Swedish explorer who named this plant after his good friend, Dr. Hugues Gaultier who expressed huge enthusiasm for the plant’s potential for tea.

Gaultheria procumbens

img_0571Gaultheria procumbens
goes by many common names such as the Checkerberry, Mountain Tea or my particular favourite la Petit te du bois meaning “the little tea of the woods”. The “tea” part of these common names refers to the fact that the leaves can indeed be brewed for tea however unlike that of Camellia sinensis, the leaves must be left to ferment in order to produce a distinct flavour. Drinkers of this mountain tea suggest that you place several leaves in a jar that can be sealed with boiling water and then cover said jar with a cloth or tea towel. The leaves must then be left to ferment for roughly 3 days in a warm environment, or at least till you can see small bubbles appearing. The liquid can be drained from the jar and stored, being diluted and warmed when required. The left over leaves are then dried and can be used again to make a more delicate flavoured tea. The leaves are evergreen and so can be harvested all year round to produce tea however it is suggested that you only take one or two leaves from each stem.

The essential oils of the leaves, known as oil of wintergreen, contains methyl salicylate and relative of aspirin and is known to act as a natural painkiller however those who are allergic to aspirin should avoid Gaultheria procumbens.

The small berries produced by Gaultheria procumbens is often referred to as “teaberries” and these are also edible with a mild minty wintergreen taste. The unripe berries are a pale green-white colour but soon ripen to a beautiful rosy red with a star-shaped depression on the bottom. They can be eaten raw or cooked to produce pies, jams or jellies.

For a very festive and minty Christmas why not try wintergreen wine – a recipe using either the leaves or the berries can be found here. Recipes for wintergreen ice cream and muffins.

#AdventBotany Day 12: Erasmus Darwin born 12 December 1731 bringing botanical love and joy to the world! By Dr M

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Advent botany couldn’t be advent botany without botanists – and amongst them are a number of significant “advent botanists”, those born in the days of advent and Dr M’s first offering on this theme is Erasmus Darwin.

Follow this link to Dr M’s blog to

Advent Botany 2016 – Day : The beauty of snowflakes microscopic algae — Culham Research Group

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By Isabelle Charmantier Bicosoeca growing on AsterionellaAh, the snowflake: symbol of short winter days, crisp frosty mornings, Carol singing under the stars and the Christmas season. However, this is not a snowflake. It is a photograph of the mass development of the flagellate protozoan Bicosoeca on Asterionella. Asterionella is a genus of pennate freshwater diatoms,…

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Advent Botany 2016 – Day 10: Hoop-petticoat daffodils — Culham Research Group

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By Jordan Bilsborrow and Kálmán Könyves Narcissus bulbocodium found in Sierra de Urbasa, Spain (J. Bilsborrow) Daffodils are very popular garden plants and an important commercial crop both as bulbs and as cut flowers. Our fascination with these very charming spring flowers has led to many cultural links in literature and art (reviewed in Hanks…

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#AdventBotany – Getting stuffed at Christmas: Onion

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Of Onions. John Gerard’s Herball, 1597.

Not much of a surprise here, but after covering sage yesterday we really had to say a few words about onions today. If you’re want to be growing your own, then t John Gerard’s herball suggests that ‘The onion requireth a fat ground well digged and dunged.’ However, as they are prone to rots and mildews, it might be better to go with some more modern horticultural advice in this instance! Gerard also reports that ‘it is cherished everie where in kitchen gardens…’ and that certainly hasn’t changed much since the 16th century. It’s fair to say that most of my cooking starts with an onion or two, despite the fact that I only have to look at one for it to make me cry.


Chopping the onion up damages the cells and causes the release of enzymes and compounds resulting in the production of an eye-irritating chemical with the catchy name syn-Propanethial S-oxide (try Scientific American for more detail). If you want to preserve your onion for posterity, it’s the sort of structure which would benefit from being kept as a spirit specimen, but we do have plenty of onion species in the herbarium collections. The Herbarium Handbook (Bridson and Foreman, 1999) recommends slicing bulbs in half before pressing them. Otherwise the bulb will still be alive in the press and may start to sprout. In 1866, the person who prepared this herbarium sheet chose leave the outside layers of the bulb and remove all of the flesh from the inside. This will have made it possible to press it, but I only hope they did this somewhere with good ventilation!

Allium cepa herbarium sheet


The onion has fleshy leaf bases (scales) which surround the budding new plant, and has papery outer layers known as tunics which protect the bulb. A bulb allows a plant to store food reserves so that it can survive a period of dormancy through adverse weather (such as wet, cold winter in the UK, or hot dry Mediterranean summers). This sort of plant is called a geophyte, as the plant’s stores are often underground, where they are better protected from frost, drought or the prying eyes of herbivores. Personally, over the holidays I shall be trying my best to be dormant on the sofa with a good supply of chocolate to see me through the dark and the cold.



#AdventBotany – Getting stuffed at Christmas: Sage

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Common sage specimen, seeds and illustration on a 19th century herbarium sheet from Leo Grindon's cultivated plant collection
Common sage specimen, seeds and illustration on a 19th century herbarium sheet from Leo Grindon’s cultivated plant collection

There are many more gastronomically interesting options available at Christmas time, but I’m still always drawn to the reassuringly traditional sage and onion stuffing. Nowadays, in addition to stuffing poultry, sage is most commonly used to flavour other meat dishes (particularly sausages in British cuisine). However, its scientific name, Salvia officinalis, shows its heritage as a medicinal herb. The species name ‘officinalis’ comes from the Latin word officina referring to a monastic storeroom for herbs and medicines. Sage was recommended for all kinds of ills, from wounds and sore throats to hair care and fertility problems. There’s something about this suggestion for ‘Great Sage’ from Gerard’s Herball, however, which seems especially appropriate for overindulgent holidays:

‘Sage is singular good for the head and braine, it quickeneth the sense and memory, strengtheneth the sinews….’ John Gerard, 1597

This year, perhaps an extra bit of sage with my turkey could give me the edge over my competitors in any after-dinner Christmas boardgames!

John Gerard's herball, 1597
John Gerard’s herball, 1597


Sage is in the mint family (also known as the Lamiacaea). Many of the plants in this family are aromatic, but sage also shows some other very recognisable characteristics such as a square stem, leaves in opposite pairs and flowers with bilateral symmetry with the five petals fused to give the appearance of an upper and a lower lip. Originating from the Mediterranean, sage enjoys plenty of sunshine and doesn’t like to get too wet over winter, but is quite tolerant of low temperatures. The furry leaves help to keep insect pests at bay, but cultivars which flower freely are very attractive to pollinating insects such as honeybees and many different bumblebees.


The sage flower has an interesting mechanism for getting pollinated. As pollinator enters the flower looking for nectar it has to push past the base of the stamens which are blocking the way. This acts as a lever, so that the stamens tip forwards and leave pollen on the back of the insect. When it visits another flower, the insect can brush against the female stigma depositing the pollen. Some bees have learnt to cheat, however, and you can find small holes at the base of flowers where a bee has bitten through and drunk the nectar from the outside.

19th century botanical teaching model of a sage flower produced by Brendel, Germany.
19th century botanical teaching model of a sage flower produced by Brendel, Germany.

Advent Botany 2016 – Day 7: The Clove — Culham Research Group

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To the microscopist, clove oil used to be one of the best smelling mounting and clearing agents when preparing samples for permanent mounting on a glass slide. However, cloves have a much wider range of uses including traditional use in herbal medicine to ease tooth-ache and to improve digestion. Cloves also make up part…

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