Saturday, 6 December 2014

Splendid spurges

Euphorbia is a remarkable genus of plants containing over 2000 species (2420 according to Encyclopedia Britannica). We have about a dozen or so native to Britain, with several other species more or less naturalised. 

The genus contains plants enormously varied in form, with some succulent species resembling cacti and others fairly described as trees. Despite this variation the flowers are generally instantly recognisable, with a female and several male flowers being clustered into a small group known as a cyathium. All species also bleed a poisonous milky juice when damaged. In the shopping concourse of central Milton Keynes some of the very large cactus-like Euphorbias can be identified if a pin is surreptitiously used to pierce the tissues; milky juice quickly oozes out. It will come as no surprise to learn that the Rubber Tree is a member of the Euphorbia family but belongs, as Hevea brasiliensis, to a different genus. A slightly less obvious member of the family is Castor Oil, Ricinus communis.

Here in Northamptonshire a number of Euphorbias, generally known as spurges, are native, with several species being common. The Wood Spurge, Euphorbia amygdaloides, is quite easily found in woodlands on limestone in the north-east of the county and was familiar to me when I was based at RAF Wittering. It is rather common too around Byfield, but here it is probably a garden escape.

Turkish Spurge in a Byfield garden, with the bright red
leaves of  Photinia davidiana in the top left-hand corner.
18 March, 2014

An attractive subspecies, E. amygdaloides ssp robbiae, often called Turkish Spurge, is commonly grown in gardens and may occasionally escape. It was early to flower in Byfield, making a vivid splash of lime-green in borders. 

Musca autumnalis on Turkish Spurge.
Byfield, 8 April, 2014

Like most (all?) spurges, E. amygdaloides 
receives numerous insect visits. Here a male Lesser House Fly, Musca autumnalis, is imbibing nectar.

When living in Byfield I grew the Cypress Spurge, Euphorbia cyparissias. It is probably a British native but is certainly not so in Northamptonshire. With its feathery foliage it is a pretty plant for the rock garden but introduce it at your peril; it has long creeping rhizomes and can become very invasive, sometimes escaping on to rough ground. I won't be growing it here in Daventry.

Cypress Spurge. Byfield, 8 April, 2014

The wise gardener will confine Cypress Spurge to a sink garden or a similar container. In the accompanying photograph the gardener has taken the risk, planting it in a border with a pretty Pulmonaria.

Another spurge in my Byfield garden was Myrtle Spurge, Euphorbia myrsinites. It is a splendid plant and has been awarded the A.G.M. We bought a plant on a visit to Beth Chatto's lovely garden near Colchester but left it behind in Byfield.

Myrtle Spurge, Euphorbia myrsinites, in my garden.
Byfield, 23 March, 2014

From south-east Europe and Asia Minor, it is a sprawling, slightly succulent plant for a sunny spot. It is an easy-going species providing it gets plenty of sunshine and is in well-drained spot. I grew it in gravelly soil where it thrived.

A closer view shows the flowers in the form of a cyathium, typical of the genus.

Caper Spurge by a track in Byfield.
9 May, 2014
The Caper Spurge, Euphorbia lathyrus, is a curiosity with its stiff, opposite leaves in four vertical rows giving it an artificial look - a tall (up to 4 feet) plant made from a kit! It cropped up from time to time in my Byfield garden from an unknown source but the seeds are suspected of remaining viable for many years so may have pre-dated our move there. A hairless biennial, it may be native in some parts of England but is usually encountered as a plant on waste ground. The fruit look like capers and there is some evidence that they have been used as caper substitutes in the past. However, they are very bitter and all spurges are poisonous, with some fatalities known. Like many spurges, the seeds are initially dispersed by an exploding fruit capsule. Spurges are myrmechororous plants: following the bursting of the fruit their seeds are further dispersed by ants. Each seed has an oily structure attached to it known as an eliaosome. The oily material is attractive to ants who will carry the seeds away, helping to disperse them and perhaps even burying them.

With lots of spurges found in Britain I will mention just one more. The Sun Spurge, Euphorbia helioscopa, is a weed - but I consider it rather attractive. I have cultivated three allotments over the years, and Sun Spurge has occurred in all of them. Although generally regarded as a native to Britain it is probably an archaeophyte - a plant likely to have been introduced over 1500 years ago. In this case,  as with many other archaeophytes it may have arrived on these shores as a crop impurity, perhaps as far back as Neolithic times.

Perhaps we shouldn't forget those which are of importance to the florist.

Euphorbia milii is regularly seen in florists' windows, as was the case with these I photographed in Daventry. This species develops extremely prickly stems and is sometimes sold as 'Crown of Thorns'. However it can hardly have been Christ's crown of thorns as this species hails from Madagascar.

Now, with the approach of Christmas, one of the most familiar of all Euphorbias forces its way into our consciousness - except that most people probably aren't aware that it is a spurge. I refer to Poinsettia, Euphorbia pulcherrima. The word 'pulcherrima' is the superlative of pulchra - beautiful, and clearly people do find it very attractive. Strangely, the origins of this plant are not clear, although Wikipedia suggests Mexico and Central America. Visitors to the Mediterranean region will find it growing on waste ground (if, like me, they like to like to poke around in such areas) where it often forms quite a large shrub.

Altogether the genus Euphorbia is of great interest and identification of the many species provides a challenge to the holidaymaker when visiting southern Europe.

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