Euphorbia lathyris

Spurge Family [Euphorbiaceae]

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1st June 2017, a garden, Coalbrookdale, Shropshire. Photo: © RWD
Note how the stem leaves, narrow lower down, suddenly change shape and is markedly broader half-way-up the plant whilst the paler-green vein becomes narrower but still distinct on the upper leaves. The bracts surrounding the inflorescence are an altogether lighter-green, differing from the other two shades of green.

15th June, a garden, Southern England. Photo: © Thomas Horsten
A striking and greyish-green spurge which grows up to 2m tall. Has a single straight upright thick stem with opposite leaves (the only inland spurge of the UK to so do). which becomes bushy about halfway up. Here there are three plants growing parallel to each other.

11th Aug 2011, a garden, Mundesley, Norfolk. Photo: © Ian Taylor
The three-lobed fruits are larger than those of other spurges, resembling capers, but they are poisonous. each lobe is more-faintly divided into two. The fruits have here lost their 3 styles each.

11th Aug 2011, a garden, Mundesley, Norfolk. Photo: © Ian Taylor
These 'upper leaves' are really bracts and are broad lanceolate and light greyish-green. Fruits 3-lobed and of similar colour.

15th June, a garden, Southern England. Photo: © Thomas Horsten
Stems continually bifurcate just above opposite paired leaves, with each pair having a flower nestling at its centre.

24th July 2012, a garden, Macclesfield. Photo: © RWD
The poisonous 'caper' is greyish and still developing here. It lies on one side and has three styles emerging from the top, each style being bifurcated into 2 stigmas at the end. Lying on the other side are a mass of anthers bearing yellow pollen. Another pair of leaves are about to un-fold (the 'double-comma' construct).

15th June, a garden, Southern England. Photo: © Thomas Horsten
The 'double comma' has a purple stem. There are also several dark shapes resembling a ball and stick model of water molecules (which have a large oxygen atom in the centre, and two smaller hydrogen atoms set at 109°). These structures, whatever they are, are all part of the flower.

1st June 2017, a garden, Coalbrookdale, Shropshire. Photo: © RWD
The inflorescences nestle in the centre of pairs of large and opposite light-green bracts. Some smaller pairs of bracts stem off from beneath the inflorescences.

1st June 2017, a garden, Coalbrookdale, Shropshire. Photo: © RWD
The inflorescence nestling at the centre of two light-green bracts. The 3-segmented globe is the fruit, complete with 3 styles still protruding. Each of the 3 segments is split into 2 internally, the division being discernible from outside on these specimens.

1st June 2017, a garden, Coalbrookdale, Shropshire. Photo: © RWD
The fruit here has turned reddish. The male parts of the flower are below the fruit. Could those be two anthers each on the four crescent-shaped objects?

1st June 2017, a garden, Coalbrookdale, Shropshire. Photo: © RWD
From the side, the four crescent-shaped floral objects seem to form a cone.

15th June, a garden, Southern England. Photo: © Thomas Horsten
The 'caper' is a seed pod and has three paired segments with three dark bands between them going from pole to pole. Each of the 6 segments probably contains one seed.

11th Aug 2011, a garden, Mundesley, Norfolk. Photo: © Ian Taylor
Round stems are robust, with lower leaves arranged in opposite pairs, pairs in quadrature. They are not in whorls of four, only seemingly so. All stems when broken will ooze a toxic and somewhat caustic milky latex. Gardeners should wear gloves. Stem leaves a darker-green than upper leaves.

15th June, a garden, Southern England. Photo: © Thomas Horsten
The leaves are a glaucous green with a pale-green (almost white) stripe down the centre-line.

15th June, a garden, Southern England. Photo: © Thomas Horsten
The stems are a beige colour and very robust.

Uniquely identifiable characteristics

Distinguishing Feature :

No relation to : Caper [a plant with similar name].

It is a biennial, taking 2 years to flower. More likely to be found in gardens, than growing wild, and even then only in the south of the UK. Cultivated as a garden plant, but it does grow natively in woods. Escapees are usually only young plants, dying later. The yield of seeds is poor. But perhaps with global warming, it is increasing its range: a report from Balvack, Aberdeenshire informs me that it has been growing for more than 15 years there.

Due to the presence of Ingenane-type and lathyrane-type (the lathyranes are named after the scientific name for Caper Spurge, Euphorbia lathyris) diterpenes Caper Spurge is toxic if eaten, although goats are not susceptible to the poisons. However, the poisons will be transferred into the milk from goats, which is then poisonous for humans to drink.

The lathyrane-type diterpenes present include Lathyrol, IsoLathyrol, EpoxyLathyrol, 7-HydroxyLathyrol and Jokinol being potent P-gp inhibitors and used in traditional Chinese medicine. Some of these compounds are shown below.

The seeds of Euphorbia lathyris contain many diterpene esters:
and lathyranoic acid.

The stem contains a white latex, which is composed of 16-hydroxy-ingenol, Ingenol and long chain unsaturated fatty acid esters.

In the mid 1980's it was being considered as a crop for industrial fuel, but your Author can find no evidence that it is now grown as a crop for oil. It seems that they were having problems with low yield of the seeds, although they contain c.40% essential oils, or the drying of the stems for burning in power stations. Perhaps they moved on to some more promising fuel crop. Certainly Zea Maize and straw are now major fuel crops in the UK.

It also contains coumarins: Daphnetin, Esculetin, euphorbetin, isoeuphorbetin and Aesculetin.

It is called the Mole Plant because it has a reputation to repel moles when growing in a garden. They are probably repelled by the toxic compounds in the roots (and elsewhere). The seed pods release their seeds explosively.


Aesculetin (aka Esculetin) is a Coumarin or more correctly, a hydroxycoumarin, shown only for comparison with Euphorbetin below. Daphnetin is isomeric with Aesculetin and is found not only in Caper Spurge but also in Mezereon, Daphne mezereon, which gave its name to Daphnetin. Coumarins and bicoumarins are toxic.


Euphorbetin, sometimes called BiAesculetin because it is a dimer of Aesculetin (where the two units of Aesculetin are upside down relative to one another) is a newly discovered bicoumarin found in Caper Spurge. An isomer of Euphorbetin, called IsoEuphorbetin is also found in the plant where the two Aesculetin units are the sane way up, and is the less stable arrangement, therefore there will probably be less of this compound within the plant.

Dicoumarol is a natural bicoumarin, not present in Caper Spurge, but present in some other plants and fungi and was discovered in mouldy wet hay made from Ribbed Melilot (Melilotus officinalis) (elsewhere known as Sweet-Clover) where, because of its anti-coagulant properties, was the cause of a bleeding disease in cattle. Once that was recognised, it came to be used medicinally as an anti-coagulant until the mid 1950's when more effective artificial anti-coagulants such as Warfarin were developed.

Anti-coagulants, which prevent the formation of prothrombin within blood thereby inhibiting blood-clotting, are used for the treatment of deep-vein thrombosis. The anti-coagulants do not dissolve blood-clots, merely prevent further clotting, which, like rust catalysing the formation of more rust, catalyses the formation of further clotting. Prothrombin normally makes blood which has escaped clot. Unfortunately, blood leaks all the time through tiny capillaries, and with prothrombin disabled, the anti-coagulants can lead to the pooling of blood outside of blood vessels; internal bleeding is an extremely bad condition. Anti-coagulants must be prescribed with care. The correct dose must be established to control the side effects. Too little or too much is harmful.

Both Coumatetralyl and Warfarin (neither of which are found in Caper Spurge) are anti-coagulants used both medicinally and as rodenticides. Rodents which consume cereals or other foodstuffs deliberately laced with either warfarin or coumatetralyl die of internal bleeding. Comatetralyl also exhibits carcinogenic and teratogenic effects. In the case of rodenticides, more effective anti-coagulant poisons have been developed such as Brodifacoum, which is also based on coumarin.

For medicinal purposes, two further anti-coagulants based upon coumarin have been developed, such as Acenocoumarol and Phenprocoumon (both of which have slightly differing characteristics to both themselves and to Warfarin). Acenocoumarol and Phenprocoumon exhibit either shorter or longer half-lives within the body, useful for some situations. Patients on Warfarin treatment should be monitored for untoward side effects and internal bleeding, which has prompted the development of yet further anti-coagulants not based on coumarin, such as Rivaroxaban and Dabigatran, and which hope to offer un-monitored treatment of deep-vein thrombosis and etc. Since none (apart from Coumatetralyl) of these anti-coagulants are produced naturally (so far as is known), they are beyond the scope of this tome.


Both Lathyrol and Epoxylathyrol are lathyrane-type diterpenes which are found in Caper Spurge. They both have an active cyclopropane unit (top right), with Epoxylathyrol also possessing an active epoxy group (bottom right). Both are toxic. Epoxylathyrane, by virtue of its extended conjugation system, can be activated by light resulting in its transformation to the cis- non-planar enone form, and thence fragmentation to a furan.

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Euphorbia lathyris

Spurge Family [Euphorbiaceae]

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