Trees: Arbutus Unedo

Autumn is a good time to check out the Strawberry tree in Waterlow Park:  you can’t miss it, spreading its evergreen multi-stemmed umbrella over the parterres of Lauderdale house.  But this is no ordinary Strawberry tree. The Royal Botanical Society insists Strawberry trees don’t fruit in these temperate northern climbs. But ours does.

It may not be laden with the little red fruit that gives the Strawberry tree it’s common name, but it makes a respectable show at fruit bearing.

The Strawberry tree is beset with mystery, but one thing we do know for certain is that in spite of its name, it is in no way related to the fruit we associate with Wimbledon and school fetes.

The Arbutus unedo, the Strawberry tree’s botanical name, has an interesting history. A Latin scholar at Channing, Highgate or St. Aloysius might wonder at the etymology of the name.  But like everything else about this tree, it is clouded in controversy. 

One school of thought believes it is a corruption from the Old French word “herbier” -- herb garden -- (herbier > herber > erber > arber > arbour and so on).  That stretches credibility a little.  More likely is that it derives from the Latin:  arbutus meaning tree/shrub or arbustus meaning plantation of trees. Pliny the Elder lends weight to this theory.  In Naturalis Historia  his encyclopaedia of the sciences published just before his death in 79AD, he explained unedo as being a contraction from the words unum edo meaning “I eat one”.

Again, we have controversy.  Some say you eat one because the fruits are so awful you never have another, others say the fruits are so delicious and head spinning that just one satisfies!  Perhaps that Latin scholar could have a go at the original text from Naturalis Historia (see the extract below) and let us know what the great man really said.

The Arbutus is native to the southern Mediterranean – particularly Spain and Portugal -- and, strangely, to Ireland.  And herein lies another conundrum.  A tree is defined as native if seed is transported by natural means such as wind or animal, but not by human.  It is impossible for the Arbutus to have appeared in Ireland without also appearing in northern France and the UK whether by bird migration or wind patterns. So why does its pollen pop up in archaeological finds in Ireland as long ago as 4000 BC but nowhere else en route from the Southern Europe? 

One theory is the Beaker people brought the seed to Ireland. The Beaker people are a mystery too – one which has taxed archaeologists for decades.  We don’t know where they hailed from as it appears they migrated great distances from different places bringing with them new bronze making technology, beer making skills and leaving behind them their trade mark bell shaped beaker that gave them their name. 

When communities migrate it is common for them to take with them seeds of plants familiar to them, and as the Beaker people seemed to congregate in Southern Europe, it makes sense that they could have brought the Arbutus seed to Ireland.  Except for two flaws. The first is that the Beaker people also inhabited Great Britain – where no evidence of Strawberry trees dating back that far have been found --  and also, their migrations were 1000 years later than the earliest Arbutus pollen found in Ireland.

The third possibility is that seeds were deposited by glacial deposits during the big thaw after the ice age. But the most recent ice age ended 14000 years ago so again doesn’t stand up to scrutiny.

But it isn’t only the Arbutus which is a mystery.  There are 14 other plants native to the Iberian peninsular which are also “native” to Ireland but not to Great Britain or northern France. They are known as the Lusitanian flora. No one has yet come up with a plausible explanation for this phenomenon.

The Arbutus unedo with its dense evergreen waxy leaves has provided welcomed relief from the hot Mediterranean sun for centuries, and is a much loved tree.  The madroño, (to give it its Spanish name) was adopted, together with the bear, as the heraldic symbol of Madrid in the 13th Century when bears were a common sight in the area. (Some suggest the tree might even have been the source of the city’s name.)  A large bronze statue of El oso y el madroño (the bear and the Strawberry tree) can be seen in the centre of the city as well as on every taxi and piece of street furniture in the city, with a bear rampant reaching up to sample the fruits of the tree.

Close by at the Prado hangs one of Hieronymus Bosch’s greatest works: “The Garden Of Earthly Desires”, a fantastical tryptych of human temptation, set between panels of heaven and hell where a multitude of naked nymphettes perch in poses that would never be mentioned in polite circles, over very large fruits of the Arbutus.

So what about those fruits?  Obviously the discerning sweet-toothed bear has a taste for them.  And birds wait patiently for them to be just right and then pluck them eagerly off the branches. But most humans who eat them find them insipid.  They’ve been likened to lychees with gritty skin.  So why do some say they are delicious? The secret is in the timing.  They are best eaten immediately after they’ve fallen.  But if they are left more than a day – especially if they’ve been bruised in the fall – their high sugar content begins to ferment and renders them unpalatable. 

The Portuguese make use of the fruit’s potency, creating Aguardente de Medronho, a brandy otherwise known as fire water.  So high is it’s level of methanol – antifreeze to the uninitiated -- that the Portuguese are forbidden by the EU to export it. It would certainly give a bear a sore head and maybe it’s this property of the fruit which lead Pliny to complain that it makes people ill. So if you see a fallen fruit in the Park – be delighted, but be warned.

The Arbutus however is not without its uses.  The autumn flowers are loved by bees as a late season snack before turning in for the winter and without the bees there’d be no fruit. It’s a food plant too for the Emperor Moth. And humans haven’t exactly spurned it.  There is no doubt the Arbutus has been spread extensively by human migration which suggests that the tree was considered useful. Because it’s multi- stemmed it’s not a tree to supply wood for building, but it’s certainly good firewood. It also has a number of medicinal properties – used by ancient people in the treatment of colds, stomach problems, TB and even is contraception.  Modern day science shows it’s high in antioxidants.  It has antibiotic qualities as well and has been used in the treatment of renal infections.  Its use for making alcoholic beverages too must have come in handy.

It also features in a number of mythologies around the world particularly in Ireland and North Western Canada where it is believed to have the power to stand firm against floods and act as an anchor for people.  In Ireland, it’s associated with the Otherworld of Celtic folklore.

Even horticulturally the Arbutus confounds convention.  It’s in the Ericaceae family of heaths, heathers and ericas which traditionally thrive in ericaceous or acidic soil.  But not the Arbutus.  It hates acidic soil, preferring to sink its roots into pH levels above the 7 mark.  It objects to having its roots disturbed so bulb planting around it is not advised, and while light pruning is OK, it must be done in late Spring after danger of frost has passed. The bark is thin and easily damaged, especially on elderly trees, which makes them prone to infection.  But looked after well it will give great pleasure to the gardener for many generations.

And herein lies a public service announcement.  The tree in Waterlow Park has been in the park for a very long time. It is extremely fragile but at the same time very inviting for a generation of young tree climbers with its low lying branches to cling on to.  But don’t be tempted.  If you love the tree just hug it, don’t climb it!


Extract from Naturalis Historia by Plinny the Elder XXViii 98 & 99

Aliud corpus et terrestribus fragis, aliud congeneri eorum unedoni, quod solum pomum simul e frutice terraeque gignitur. arbor ipsa fruticosa. fructus anno maturescit, pariterque floret subnascens et prior coquitur. mas sit an femina sterilis, inter auctores non constat.
pomum inhonorum, ut cui nomen ex argumento sit unum tantum edendi. duobus tamen his nominibus appellant Graeci comaron et memaecylon, quo apparet totidem esse genera; et apud nos alio nomine arbutus vocatur. Iuba auctor est quinquagenum cubitorum altitudine in Arabia esse eas.