Occasional paper: St. Anthony’s Turnip

Mostly I leave Sunday photography to our colleague, the estimable Chris Bertram. Still, this Sunday I was walking the dog in the hills above my town. (“My town” being a modest community of a couple of thousand people in the rolling countryside of northern Bavaria.)


[copyright me, yesterday]

And by the side of a grassy meadow, I stopped to photograph this pretty little yellow flower:

[they look so innocent]

A moment with the app revealed that this was Ranuncula bulbus, the Bulbous Buttercup.  There are a bunch of species in the genus Ranuncula, which is another way of saying there are a lot of different kinds of buttercup.  That’s because buttercups appear to be a recent evolutionary radiation, and a pretty successful one.

But when I did a quick search on these little guys?  I found they used to have another name.  The Bulbous Buttercup was once known as Saint Anthony’s Turnip.

Saint… what?

Let’s start with the “Bulbous” part.  The Bulbous Buttercup is so called because it has a bulb.  Specifically, it has a “corm” — an enlarged stem, just below the surface, that stores energy in the form of starch.  


[pedantry: corms are enlarged stems, while true bulbs like onions are enlarged roots]

The next thing to know is that buttercups are pretty toxic to humans.  The leaves and stems, the sap, the flowers, and the corm — all bad.  Eating one buttercup won’t kill you, but it could make you sick.(1)  And buttercups are a significant menace to horses and cattle, who are also vulnerable to the toxins.  Google around and you’ll find lots of online articles about how to kill this pretty-but-dangerous little flower if it shows up in your pasture.  So while that crunchy little corm has lots of calories — starch and a bit of protein — it’s not going into any salads.

(1) The lethal dose for humans seems to be about 500g, or about a pound of fresh buttercup greens.  So you’d have to work at it, fair enough. 

However: while humans, horses and cows are vulnerable to the buttercup toxin?  Swine are not.  Pigs will cheerfully eat a buttercup and ask for seconds.  In fact, since the corms grow close to the surface, it’s very easy for swine to root them up.  A meadow full of buttercups?  For a pig, that’s a tasty, nutrient-rich buffet.

So how does that connect to “Saint Anthony’s Turnip”?  Well, that’s easy: it’s because St. Anthony is the patron saint of swineherds.


[Saint Anthony accompanied by a pig, 15th century]

Which… okay, there are a lot of Catholic saints, and most of them are patron saints of something or other.  Pretty much every profession has a patron saint, from funeral directors (St. Joseph of Arimathea) to bartenders (St. Armand of Maastricht). (2)  “Swineherd” is one of those jobs that basically no longer exists but that was really quite important for thousands of years.  So it makes perfect sense that there would be a patron saint of swineherds.   

(2)  Some professions have multiple patron saints.  Lawyers, for instance, have three or four.  Catholic lawyers know the Lawyer’s Prayer to St. Thomas More, which gives good advice even if you’re neither a lawyer nor Catholic.  

But wait a moment.  Is this… the Saint Anthony?  Saint Anthony the Great?  The third-century Roman who gave up all his wealth and went out into the Egyptian desert to become a hermit, where he was alternately tormented and tempted by demons?  That Saint Anthony?

[copyright Michelangelo Buonarotti, c. 1487)

Yup, that’s the guy.

So the original story of St. Anthony comes from a Roman bishop named Athanasius, who wrote a Life of Anthony sometime in the late fourth century.  I went back to look at that original text (pdf).  And while the Life has both the temptations and the torments, there’s nothing about pigs.

But somewhere, somehow over the centuries a bunch of legends and traditions accreted around St. Anthony.  So, there’s a legend that a demon possessed a wild pig in order to threaten the saint, and then Anthony cast out the demon, and the grateful pig became his friend and companion.   In another story, Anthony healed the piglet of a wild sow, which caused the sow to follow him around like a pet.  There are a number of these. 

Which is all perfectly common and normal for saints, especially early / OG saints. (3)  But as to why pigs particularly… nobody seems to know.


[but there it is]

(3) St. Anthony is also associated with fire — see him standing in flames in the middle image above?  There are like three different legends associated with that and I’m not even going there.

So if you have a nodding acquaintance with European art history, you know there’s a vibrant tradition of pictures about the Temptations of Saint Anthony, from Hieronymus Bosch —


[as Bosch goes, relatively restrained]

— to Salvador Dali.


[Dali painted this for a contest!]

The subject matter gave artists pretty free rein, after all.  They could depict the grotesque, monstrous, surreal or erotic —

[but note stalwart companion pig]

— sometimes to the extent that the saint himself simply vanishes under a mass of demonic weirdness.


[tbf this is Max Ernst, and… yeah, it’s Max Ernst.]

And of course, the modern internet has joined the fun.





But okay!  Somehow St. Anthony became associated with a pig.  So you have a tradition of Anthony depicted as tormented and/or tempted, and another tradition showing him with a pig.


[or sometimes both]

And based on the pig connection, Anthony became the patron saint of swineherds. (4)  And thus, the pig-edible Bulbous Buttercup became St. Anthony’s Turnip.  All done, then?

(4)  I went down a whole side-bar rabbit hole on swineherds — everything from the Gadarene Swine to Circe to the dueling shapeshifting swineherds of Irish legend.  TLDR, the status of swineherds varied wildly over times and places, but they were associated with various sorts of magic and weirdness way more often than you might think.  

Well… there are a couple of other things.  In England there was a tradition of taking the smallest pig of a litter — what today we would call the runt — and donating it to the Church.  And these little pigs were known as tantony pigs, with “tantony” being a contraction of “Saint Anthony’s”.  This in turn led to occasional use of “tantony” as a verb, meaning to follow someone superior like a little pig following its mother.  The word is now entirely obsolete, but now and then it still pops up.

The other thing has nothing to do with pigs or saints.  If you’re British, Irish or American you might recall a child’s game where a child holds a buttercup under your chin, and if your chin turns yellow, it means you like butter.  Nobody has any idea where that comes from, but it’s true that if the sun is shining, and you hold a buttercup under your chin, you can get a surprising yellow-gold glow off the buttercup.



[if you’ve never tried this, check it out, it’s actually pretty cool]

So the reason this happens is because buttercups are very glossy and reflective.  Is this just random?

No.  According to this paper (“Functional Optics of Glossy Buttercup Flowers”), there are a couple of reasons for it.  One is what you’d expect — it’s probably more attractive to potential pollinators.  But the other is this:

“Buttercup flowers are heliotropic and when ambient temperatures are low they have approximately the shape of a paraboloid.”

— A heliotropic flower is one that, over the course of a day, turns to face the sun.  A paraboloid is the three-dimensional version of a parabola.  It has the interesting property that anything striking its inner surface tends to get bounced or reflected directly to a single point in its center.  So…

“Under these circumstances, incident sunlight that reaches the petal surface under a large angle will not be reflected to the outside but towards the central flower area where the reproductive structures are located. This will cause increased floral temperatures, which enhances seed and pollen maturation and is preferred by pollinators… Indeed, under natural conditions, the centre of the paraboloid-shaped glossy flowers of the arctic buttercup, R. adoneus, were found to be several degrees warmer than the ambient air.”

In other words, the buttercup is a little solar oven.  It focuses sunlight into its center, partly to keep its own genitals warm, but also as a boon to pollinators.  On a cool but sunny spring morning, cold-blooded insects will prefer the flowers that literally warm them up, allowing them to bask in concentrated sunlight.  


[like a cozy snuggle in a warm blanket]

So the sun-focusing buttercups will get pollinated preferentially over flowers that don’t have this ability.

If you’re a science fiction nerd, you might remember that an author named Larry Niven once proposed an alien plant called a “sunflower”.  It grew a flower with a mirror surface that could reflect and focus sunlight…

A single species of plant evenly dispersed across the land, from here to the infinity-horizon. Each plant had a single blossom, and each blossom turned to follow Louis Wu as he dropped. A tremendous audience, silent and attentive.

He landed and dismounted beside one of the plants. The plant stood a foot high on a knobbly green stalk. Its single blossom was as big as a large man’s face. The back of that blossom was stringy, as if laced with veins or tendons; and the inner surface was a smooth concave mirror. From its center protruded a short stalk ending in a dark green bulb.

All the flowers in sight watched him. He was bathed in the glare. Louis knew they were trying to kill him, and he looked up somewhat uneasily; but the cloud cover held.

“You were right,” he said, speaking into the intercom. “They’re Slaver sunflowers. If the cloud cover hadn’t come up, we’d have been dead the instant we rose over the mountains…”

There was no alien survivor anywhere in the domain of the sunflowers. No smaller plant grew between the stalks. Nothing flew. Nothing burrowed beneath the ashy-looking soil. On the plants themselves there were no blights, fungus growths, disease spots. If disease struck one of their own, the sunflowers would destroy it.

The mirror-blossom was a terrible weapon. Its primary purpose was to focus sunlight on the green photosynthetic node at its center. But it could also focus to destroy a plant-eating animal or insect. The sunflowers burned all enemies. Everything that lives is the enemy of a photosynthesis-using plant; and everything that lived became fertilizer for the sunflowers.

Niven wrote that around 1970. The first papers on buttercup reflectivity appeared in the 1990s, decades later.  So, coincidence.

That said… I mentioned at the start that buttercups seem to be a fairly recent and successful evolutionary radiation, with a bunch of related species spread widely across several continents.  At a guess, the reflection is probably the reason.  Apparently all buttercups do it.  And it is, in biological terms, rather novel.  (5)  So who knows how far the buttercups might take this trend, millions of years from now?

(5) Edit, added one day after the original post:  the “paraboloid reflective petals -> miniature solar oven” trick appears to have evolved independently several times, though buttercups seem to go harder than most.  I belatedly found this excellent recent survey paper, which gives an overview of the various tricks flowers use to warm themselves up.

Anyway: I snapped a casual photo while walking the dog, and boom — an hour later I was reading about corms, Catholic hagiography, and the physics of paraboloids.  We all learned that little Tennyson poem back in school, right?

Flower in the crannied wall,
I pluck you out of the crannies,
I hold you here, root and all, in my hand,
Little flower—but if I could understand
What you are, root and all, and all in all,
I should know what God and man is.

And that’s all.