By Claire Smith
Katharine Murray Lyell’s book, A Geographical Distribution of All the Known Ferns, was published by John Murray (who was also Charles Darwin’s publisher), in January 1870. Continue reading
Katharine Murray Lyell’s book, A Geographical Distribution of All the Known Ferns, was published by John Murray (who was also Charles Darwin’s publisher), in January 1870. Continue reading
The aim of my PhD is to identify which ornamental plants might become invasive in the future, possibly as a result of climate change. Gardeners have an important role in preventing invasive ornamental plants from escaping gardens, through their choice of plants, adopting good gardening practices and disposing of plants responsibly. This was the message of our gold medal winning #GardenEscapers exhibit at RHS Chelsea Flower Show last year.
The premise of Wild about Weeds – as the author puts it “garden design with rebel plants” – is therefore of great interest to me. The book discusses how weeds can – and should – be embraced in gardens. Indeed, the author goes further and suggests weeds that gardeners should be encouraged to consider as integral elements of a garden. It’s full of example weeds, and beautiful photos giving the reader inspiration on how weeds can look great in their garden.
It’s challenging to distinguish between a ‘weed’ and an ‘invasive’ plant. So, let’s briefly try and understand what a ‘weed’ is. I would personally suggest ‘a plant which (insists) on growing where it is not wanted’, which of course doesn’t fit with embracing weeds as integral to the planting palette of a garden. Wallington defines a weed as “a plant that reproduces seemingly uncontrollably”. Weeds can indeed reproduce uncontrollably, which is why they often appear in undesirable spots, but are weeds invasive?
Despite often being used interchangeably, a ‘weed’ and an ‘invasive plant’ are not the same, yet neither are they mutually exclusive terms. An invasive plant is a non-native species which has a detrimental ecological and/or economic impact. A weed, if we follow the author’s definition, can be native or non-native, and perhaps described as a ‘thug’ (i.e. uncontrollable). Importantly, a ‘weed’ should apply to plants which are problematic for gardeners, within gardens, and not if it has a detrimental impact in the wild.
In his introduction, the author alludes to the issue of invasive species with the example of lupins (Lupinus sp.) in New Zealand, of which he says “in the wild [these are] a problem for native plants and wildlife, but in gardens there is no denying their towering beauty”. I don’t disagree with this; invasive plants can certainly be beautiful. Their beauty is often the reason they were introduced as ornamentals in the first place. However, invasive species are one of the main threats to native biodiversity. In Britain and Ireland, most of our invasive plants originated from our gardens. It is therefore important to consider whether a weed is – or could be – invasive in the wild.
So far, it might seem that I’m reluctant to embrace weeds. I’m not, I agree with the author that – beyond aesthetics – many weeds serve a very useful function in the garden such as filling “a gap where nothing else grows”. Weeds can be sustainable options, thriving without the need for input such as water, and they provide resources for wildlife, e.g. pollinators.
Wallington divides weeds into the good, the bad and the unappreciated. ‘Good’ weeds are those that share the same characteristics as any weed, such as self-seeding profusely, yet they are – for whatever reason – already embraced and encouraged by many gardeners. Examples include the native primrose (Primula vulgaris) and the bluebell (Hyacinthoides non-scripta).
Also included as a ‘good’ weed is Mexican fleabane (Erigeron karvinskianus). This is undoubtedly a pretty plant; it has an unruly and unkempt habit which makes it look rather ‘natural’ growing in cracks and along walls, as it if belongs. Yet, as the name suggests, it originates from Mexico. It is a species which could become increasingly problematic, perhaps invasive, in the wild. I’ve seen it dominate walls in Jersey, enjoying the slightly warmer climate perhaps.
The book continues with examples of ‘bad’ weeds, plants that (most) gardeners do not want because they are very difficult to get rid-of once they’re in your garden. The ‘bad’ weeds include invasive species (at least here in Britain and Ireland), such as Japanese knotweed (Reynoutria japonica, syn. Fallopia japonica) and Himalayan balsam (Impatiens glandulifera) which he described as “a very pretty weed with beautiful, sweetly scented pink flowers”. The author acknowledges that it is “very invasive in damp soils and especially on the banks of streams…”. Both plants fall under UK legislation in efforts to control them as invasive species.
The rest of the book is dedicated to the ‘unappreciated’ weeds, and I’ll pick one example, the bellflowers (Campanula poscharskyana and C. portenschlagiana). For me, bellflowers exemplify differing attitudes amongst gardeners towards weeds. They grow in my grandparents’ garden, thriving in cracks in walls and paths. For my Taid (grandfather) it is a weed, which should be removed. For my Nain (grandmother) however, it might well be a weed but it’s a beautiful plant that can successfully grow in corners where even the best gardener would fail to succeed in adding colour. For that reason, it’s a weed which stays.
Wallington writes an interesting profile for each ‘unappreciated weed’, including how to bring them into your garden by ‘weed hunting’ or propagating and how to manage them. To many gardeners (myself included) this seems very odd – at least initially – but why not?
The plant profiles also include comments on ‘invasiveness’; within gardens and also occasionally referring to their invasive status in the wild. Here is criticism of the book. The author encourages us to embrace these ‘unappreciated weeds’ and bring them into our gardens. I agree with this in principal, but he doesn’t give sufficient emphasis on the detrimental impact that invasive species can have in the wild. If a weed is a ‘thug’ in the garden, it’s possible for it to behave the same in the wild at the detriment of native biodiversity.
As I’ve said, a weed and an invasive plant are not the same. Yet, some weeds are invasive and shouldn’t be encouraged in gardens. Other weeds are more difficult. One example is the butterfly bush (Buddleja davidii), an ‘unappreciated weed’. It’s undoubtedly beautiful; its purple flower spikes are normally covered in butterflies. However, it’s arguably invasive here, although doesn’t fall under legislation, but it is also an obvious resource for pollinators.
In the introduction, the author says that the book is for gardeners who (among other things) want to be ecologically responsible. My criticism is not necessarily of the inclusion of any particular plant – especially as the invasive status of a plant depends on where in the world the reader is gardening – but on a missed opportunity to emphasise how important gardeners are in preventing invasive ornamental plants from escaping gardens. There needs to be a better discussion among gardeners on invasive species.
And so, what is a weed? Further, why is one plant considered a weed (e.g. herb robert) and others – perhaps forget-me-not (Myosotis sylvatica) – not? Such questions cannot be answered with certainty, the answers are too subjective and thus individualistic. However, the author will undoubtedly inspire many gardeners to look at their weeds differently. Wild about Weeds is an insightful book, and very topical with an increasing interest in ‘naturalistic’ gardening for which weeds should be considered. Let’s embrace weeds, but with care!
Wild about Weeds by Jack Wallington. Laurence King Publishing. £19.99. ISBN 978-1786275301
See also a review in Gardens Illustrated.
The Lost and Found Fungi (LAFF) project have been travelling the country, teaching fungal enthusiasts DNA barcoding… With attention to detail, and a little luck, the protocols have been teaching allow you to read the DNA of the life around us.
Deck the Halls with Boughs of Holly… But not until Christmas Eve, otherwise you’ll have bad luck! Once your holly (Ilex aquifolium) and other festive evergreens are in place, it is also unlucky to either remove them before, or leave them up after, Twelfth Night. When you do take down your decorations it’s very important to be as careful as possible, lest you be infested not with cheery little Christmas elves, but terrifying goblins. The number that you see is determined by how many leaves you allow to fall to the ground.
Robert Herrick (of “gather ye rosebuds while ye may” fame) wrote this festive poem about the customs in his Devon village:
Down with the rosemary and so
with the baies and mistletoe,
Down with the holly, ivie, all
Wherewith you drest the Christmas hall.
That so the superstitious find
Not one least branch there left behind,
For look, how many leaves there be,
Neglected there, maids trust to me,
So many goblins you shall see.
If you had over-indulged yourself at Christmas dinner in 1653 (which you shouldn’t have done, as Christmas was cancelled between 1647 and 1660), then you might have turned to Nicholas Culpeper’s Complete Herbal, which recommended Holly as a remedy for your stomach ache:
“The berries expel wind, and therefore are held to be profitable in the cholic. The berries have a strong faculty with them; for if you eat a dozen of them in the morning fasting when they are ripe and not dried, they purge the body of gross and clammy phlegm: but if you dry them into powder, they bind the body…”.
There were many other medicinal remedies ascribed to holly. Drinking fresh milk from a cup carved from variegated holly wood was considered an effective cure for whooping cough, and chilblains could supposedly be improved by thrashing your feet with the leaves. According to Margaret Baker, “An unpleasant English recipe for the treatment of worms advised the patient to yawn over a dish of sage and holly leaves in water, whereupon the worms would drop out of his mouth.”
Note: please do not try any of these remedies at home! Holly berries contain saponins that act as an emetic, which means they’ll make you sick. (This is what Culpeper means by purging the body.) Modern advice for the treatment of chilblains advises not doing anything that might scratch or break the skin, so no flagellating your feet with holly please!With the exception of the period between Christmas Eve and Twelfth Night, it has long been considered extremely bad luck to cut down a holly tree. For this reason they were often seen standing proud of other species in the hedgerows, with the added benefit that their tall and prickly presence prevents ill-intentioned witches from running along the tops of the hedges.
Culpeper also reports that, “Pliny saith, the branches of the tree defend houses from lightning, and men from witchcraft”. This is a common idea that seems to have been repeated in slightly varying forms for centuries. As well as witchcraft and lightning, planting a holly tree outside your house will apparently protect you from thunderstorms, fire, sorcery, and the evil eye. These benefits are enhanced if the tree is a self-seeded volunteer rather than one that you’ve planted yourself, and holly picked on Christmas Day is particularly powerful.
What Pliny actually says is “aquifolia arbor in domo aut villa sata veneficia arcet”, which translates literally as “a holly tree by your town house or country house protects against poisoning”. In the 1938 edition W.H.S. Jones translates this as “magic influences”, and I would be very interested to find out at what point “poisoning” becomes “magic” and “witchcraft”. Further investigation is needed — and of course I may be wrong about the Latin, as it’s not my area of expertise!
If you want to create your own magic with holly, you need to gather nine leaves of “she-holly” and tie them with nine knots into a three-cornered handkerchief. It’s very important to do this in silence, at midnight, on a Friday. If you maintain the silence until the following morning, the person you desire will appear to you in your dreams. “She-holly” is described as being without spines which symbolises the feminine, in contrast with the masculine symbol of the prickly he-holly leaves.
Despite the fact that only female holly bears the berries, it has long been considered a male symbol and, as such, it was important that holly was brought indoors only by a man. Being an indicator of fertility (not to mention another repeller of witches), the rich red berries were vital. Berryless holly was considered incredibly unlucky to bring indoors – to the extent that if it was a poor winter for berries, it was permissible to redden ivy berries with sheep raddle (dye used for marking sheep), and add these artificial clusters to the wreath. To maintain domestic harmony, an equal quantity of both smooth and prickly holly could be used to decorate the home.
Holly magic also worked on animals. A stick of holly brought back wandering cattle, a holly collar protected your horse from witchcraft, and holly leaves in your seed drill would keep away mice. Cows would thrive if a sprig of holly was pinned up in the cowshed – particularly if it had previously been used to decorate a church. As a symbol of Christianity (the prickly leaves representing Christ’s crown of thorns, and the berries his blood), it was thought that animals revered the holly and would never damage a tree by eating it. In fact, sheep can eat holly, if the branches are cut and left out in the field for a week or two. Holly being fed to cattle was a widespread practice until the eighteenth century, although we now know that it contains cyanogenic glycosides and alkaloids which are poisonous to horses and livestock.
One practical use of holly that persisted into the twentieth century was in the making of “bird-lime”. This sticky substance was originally used for the trapping of small birds. It was cooked up by extracting the juice of the boiled bark and mixing it with nut oil. Perhaps its most surprising use was during the Second World War, when it was used as an adhesive during the development of the “Grenade, Hand, Anti-Tank No. 74”, or “sticky bomb”. An alternative sticky substance was quickly developed by Kay Brothers Ltd in Stockport, but without the inspiration of the holly infused bird-lime, the British Army could well have taken much longer to come up with a solution to the shortage of anti-tank weaponry which they faced following the 1940 evacuation of Dunkirk.
Baker, Margaret, Discovering Christmas Customs and Folklore, Princes Risborough, Shire Publications, 1992
Baker, Margaret, Discovering Christmas Customs and Folklore, Aylesbury, Shire Publications, 1972
Baker, Margaret, Discovering the Folklore of Plants, Aylesbury, Shire Publications, 1980
Culpeper, Nicholas, The Complete Herbal and English Physician Enlarged, London, Richard Evans, 1814 edition https://archive.org/details/cu31924001353279/page/n113
Kightly, Charles, The Perpetual Almanack of Folklore, London, Thames & Hudson, 1987
McNeill, Murdoch, Colonsay, one of the Hebrides, its plants: their local names and usses–legends, ruins, and place-names–Gaelic names of birds, fishes, etc.–climate, geological formation, etc, Edinburgh, David Douglas, 1910 https://archive.org/details/colonsayoneofheb00mcneiala/page/110
Vickery, Roy, Vickery’s Folk Flora: an A-Z of the Folklore and Uses of British and Irish Plants, London, Weidenfield & Nicholson, 2019
WW2 People’s War: An archive of World War Two memories – written by the public, gathered by the BBC (page archived from October 2014) Sticky bombs, manufactured by Kay Brothers, Stockport by Stockport Libraries https://www.bbc.co.uk/history/ww2peopleswar/stories/12/a2159912.shtml
Pliny the Elder, Natural History, Volume 6, Book 24, para 72 1938 edition, English translation by W.H.S. Jones https://www-loebclassics-com.idpproxy.reading.ac.uk/view/pliny_elder-natural_history/1938/pb_LCL393.85.xml?rskey=UodQOI&result=1
Hosking, Rebecca & Tim Green, Holly – Returning To An Ancient Tradition On The Farm, Permaculture, Sunday, 3rd April 2011
Ornamental plants: our future invaders? This seemingly simple question is the focus of my PhD, and I’m asking gardeners to help me answer it. Most of the invasive plants we have in the British Isles originally escaped from gardens (Stace and Crawley, 2015) and that’s why gardeners have an important role to play. The challenge is to identify which ornamental plants – not currently problematic – have the potential to become invasive in a changing climate.
So far, over 800 gardeners have reported plants that are invading or taking over their garden. The ‘top three’ plants so far have been: Japanese anemone (Anemone × hybrida), lady’s mantle (Alchemilla mollis) and montbretia (Crocosmia × crocosmiiflora).
This is interesting because these plants are at different stages of the invasion process. Although montbretia can be invasive, neither Japanese anemone nor lady’s mantle are currently invasive in the British Isles. Could they be our future invaders?
You can help me reach 1,000 responses by completing the survey here. It’s open to all gardeners across the United Kingdom or the Republic of Ireland until December 31st.
Stace, C.A. & Crawley, M.L. (2015). Alien Plants. Harper Collins, London.
In 2014 I introduced the food of the gods, Theobroma cacao, as the source of chocolate, that staple of Christmas excess, in the 16th Advent Botany post. Today, in the second for 2019, I explore Theobromine, perhaps the best known chemical compound in chocolate, and one of the many chemicals that make it so popular.
Theobromine, is a xanthene alkaloid like caffeine, and is formed during the metabolic breakdown of caffeine as well as ocurring naturally in cocoa and some other plants. It reduces sleepiness by blocking adenosine receptors, it dilates blood vessels and relaxes smooth muscle tissue in the lungs. The effects are long-lasting with a half life of around three hours in humans and it has been shown to have a mood improving effect. This contrasts with 5-6 hours half life for caffeine.
Theobromine can be toxic in high concentrations (Finlay & Guiton, 2005) but the LD50 (median lethal dose) is around 0.5-1 gram per kilo of body weight so a 70 kg (11 stone) adult would need to eat 35-70g of Theobromine (ca 10kg of dark chocolate) to be fatal.
Before that, the vomiting and diarrhoea of Theobromine toxicity would have cut in. This is conjecture, of course, as the estimates are based on experiments with rats. Human experiments have not been conducted. I could find no reported case of death by chocolate in humans. In cats and dogs the lethal dose is lower (ca 0.3g Theobromine per kg body weight) and they metabolise the theobromine more slowly (a half life of 18 hours has been reported) so 2 kg of chocolate could deliver the fatal dose to a small dog. Again, the symptoms of the toxicity are likely to clear the chocolate from the system before that point is reached.
So, please enjoy your chocolate sweets over the Christmas period but don’t over-eat!
Anon Does Chocolate contain drugs? — Molecules found in Chocolate, The Science of Cooking (Accessed 31st November 2019)
Finlay, F., & Guiton, S. (2005). Chocolate poisoning. BMJ : British Medical Journal, 331(7517), 633.
Welcome to #AdventBotany 2019 and the start of another journey into quirky, curious, hostorical and, above all, botanical information about the plants associated with the winter season.
This year I’m expanding on John Warren’s story of Tangerines and virgin birth told in 2015 with my explorations into the identity of the smaller fruited citrus. I’ve often seen and bought fruit variously under the names Clementine, Satsuma and Tangerine and felt that, to an extent, they were all rather similar. However I am not the only one to have wondered about the mysteries of Citrus.
There are four species of Citrus widely treated as the wild ancestors of most cultivated ones: C. reticulata, C. maxima, C. medica, and C. micrantha.
All cultivated Citrus are eastern in origin including the wild mandarin.
Ideas of the derivation of cultivated Citrus from these four ancestral species is depiceted in an excellent illustration from Recent insights on Citrus diversity and phylogeny
Genomic studies of Citrus have shown more detail on the relationships of genomes in the cultivated species (Curk et al., 2014; Velasco & Licciardello 2014; Wang et al. 2017) including maps of the nine basic citrus chromosomes and have identified candidate genes for asexual seed production (apomixis via nucellar polyembryony) which has been important in the domestication of these fruit. In 2018 (Wu et al. 2018) further insights into the genomics of Citrus investigated ten wild species, using genomic, phylogenetic and biogeographic analysis. They propose that “citrus diversified during the late Miocene epoch through a rapid southeast Asian radiation that correlates with a marked weakening of the monsoons. A second radiation enabled by migration across the Wallace line gave rise to the Australian limes in the early Pliocene epoch.”Their research suggests that sweet orange and mandarins are extensively interrealted and have evidence of pummelo genes through hybridization. Work by Oueslati et al. (2016) offers an insight into quite how closely related the various Citrus cultivars areSo I now have a better idea of how and when citrus evolved intot he varieties we now enjoy but I still can’t tell the fruit apart!
The article in independent.ie is perhaps the most accessible suggesting:
Clementines are the sweetest of the small orange citrus, and have a skin that peels fairly easily.
Tangerines gain their name from the north African exports of Citrus via the port of Tangiers. Tangerines are a form of mandarin orange and are the hardest of these three to peel but have a richer, sweeter flavour than the others.
Satsumas have an easy to peel skin due to a thick but loose albedo (the white layer under the orange skin) so the central segments can be freed readily from the peel.
So I can now tell what to expect when shopping for these winter season fruit.
Curk F, Ancillo G, Ollitrault F, Perrier X, Jacquemoud-Collet J-P, Garcia-Lor A, et al. (2015) Nuclear Species-Diagnostic SNP Markers Mined from 454 Amplicon Sequencing Reveal Admixture Genomic Structure of Modern Citrus Varieties. PLoS ONE 10(5): e0125628. https://doi.org/10.1371/journal.pone.0125628
Luro, F., Curk, F. Froelicher, Y. & Ollitrault, P., Recent insights on Citrus diversity and phylogeny. Publications du Centre Jean Bérard, (2017) https://books.openedition.org/pcjb/2169
Oueslati, A., Ollitrault, F., Baraket, G. et al. Towards a molecular taxonomic key of the Aurantioideae subfamily using chloroplastic SNP diagnostic markers of the main clades genotyped by competitive allele-specific PCR. BMC Genet 17, 118 (2016) doi:10.1186/s12863-016-0426-x
Wang, X., Xu, Y., Zhang, S. et al. Genomic analyses of primitive, wild and cultivated citrus provide insights into asexual reproduction. Nat Genet 49, 765–772 (2017) doi:10.1038/ng.3839
Wu, G., Prochnik, S., Jenkins, J. et al. Sequencing of diverse mandarin, pummelo and orange genomes reveals complex history of admixture during citrus domestication. Nat Biotechnol 32, 656–662 (2014) doi:10.1038/nbt.2906 [Preprint here]
Wu, G., Terol, J., Ibanez, V. et al. Genomics of the origin and evolution of Citrus. Nature 554, 311–316 (2018) doi:10.1038/nature25447
To hone my teaching skills and learn useful practices I have started following a number of established teaching blogs. These include:
Thoughts on chemistry and education;
Reading for Learning;
Newton’s Laws of Learning;
Mr T’s Blog: Keeping it simple!;
The Fruits Are Sweet and;
September 2019 was the start of the school year, as well as the start of yet another year of University for myself! This will be my 8th… Continue reading
Publications can take time – it has been almost six months since I first submitted this paper and years since the start of the research towards it! Continue reading
This gallery contains 2 photos.
Here is the poster I delivered at the State of the World’s Fungi (SOTWF) Symposium 2018. This was a grand and audacious event incepted and hosted by the Royal Botanic Gardens, Kew.