A plethora of amazing facts – which plants are the tallest and smallest, the smelliest and deadliest – have been collated by Christina Harrison, a specialist in plant ecology and garden history, and Lauren Gardiner, a research fellow at Kew, for their latest book, Bizarre Botany, an A to Z revealing some of the quirkiest stories about plants.

Ham & High: Christina Harrison and Lauren Gardener, authors of Bizarre Botany, published by Kew. PA Photo/Rupinder VirdiChristina Harrison and Lauren Gardener, authors of Bizarre Botany, published by Kew. PA Photo/Rupinder Virdi (Image: Archant)

“We are fascinated by plants, but we are also excited by how many unusual and fantastic new plant stories we hear all the time, from bizarre uses of plants to discoveries of strange new interactions between plants and animals, insects or fungi,” the authors explain.

Here are 10 of their findings – test your green-fingered relatives on their knowledge of flora and fauna this festive season.

Ham & High: Daffodils in bloom. PA Photo/thinkstockphotosDaffodils in bloom. PA Photo/thinkstockphotos (Image: Archant)

1. Bulbs can alleviate dementia. Extract of some species of snowdrop and daffodil contain galantamine, which has been shown to help nerve cells in the brain communicate with each other, thus relieving some symptoms of dementia.

Ham & High: Ginkgo biloba green leaves on a tree. PA Photo/thinkstockphotosGinkgo biloba green leaves on a tree. PA Photo/thinkstockphotos (Image: Archant)

2. The Ginkgo biloba tree, commonly known as the maidenhair tree, is extraordinarily resistant to forces that would kill most other plants. Six such trees grow around a mile from the centre of Hiroshima, Japan, having survived the 1945 atomic bombing. At that distance from ground zero, almost everything else living died instantly, but the burnt trees survived, re-grew and are still growing today.

3. Fancy a coffee? Surprisingly, honeybees also like caffeine. Some plants like the coffee plant and citrus species have a dash of caffeine in their nectar to help honeybees remember their flower as a good source of nectar and to encourage the bees to keep coming back.

4. Plants can be masters of disguise. Dracula orchids that grow in the cloud forests of Ecuador lure in fruit flies as pollinators by pretending to be mushrooms. Their petals resemble a mushroom and they also emit a mushroomy scent.

Ham & High: Wild chamomile flowers. PA Photo/thinkstockphotosWild chamomile flowers. PA Photo/thinkstockphotos (Image: Archant)

5. Know which plants were used in the Egyptian art of embalming? Tutankhamun is thought to have been embalmed in the traditional way - washed and oiled, then wrapped in layers of linen bandages made from the flax plant, among which were placed juniper berries. Once the body was mummified, fresh floral garlands were draped over it, featuring olive and date palm leaves, pomegranate and willow leaves, cornflower and chamomile.

6. Unsurprisingly, broadcaster and naturalist Sir David Attenborough has a number of plant namesakes. There’s a Welsh member of the daisy family called Hieracium attenboroughianum, a plant from the Philippines called Nepenthes attenboroughii and a genus in the Annonaceae family called Sirdavidia.

7. More surprisingly, two begonias are named after Star Wars characters – Begonia darthvaderiana and Begonia amidalae.

Ham & High: Slices of cucumber. PA Photo/thinkstockphotosSlices of cucumber. PA Photo/thinkstockphotos (Image: Archant)

8. Cucumber - fruit or veg? It’s actually a fruit. The best clue is that a cucumber has seeds inside - which a vegetable does not. Other fruits commonly labelled as veg include butternut squash, olives, aubergines, courgettes, peppers and tomatoes. Rhubarb, on the other hand, may be mistaken for fruit but is actually a veg.

Ham & High: Carolina Reaper chilli. PA Photo/thinkstockphotosCarolina Reaper chilli. PA Photo/thinkstockphotos (Image: Archant)

9. There’s hot competition among growers to produce the hottest chilli on record. In 2013 the ‘Carolina Reaper’ became the current Guinness World Record holder and ethno-botanist James Wong estimated that a single one could be used to make 500 litres of curry. Yet only mammals are affected by a chilli’s heat. Birds can gorge themselves, completely unaffected.

10. Yawn-inducing lettuces? Apparently these salad staples may have a soporific effect if you go for some wild species, such as Lactuca virosa. Some Lactuca types exude a milky fluid when their leaves are cut, known by some as ‘lettuce opium’, which can act as a sedative. But take comfort from the fact that modern cultivated lettuces have had the bitterness – and sedative quality – bred out of them.

Bizarre Botany by Christina Harrison and Lauren Gardiner is published by Kew, priced £10