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{{Taxobox
| name = ''Euphorbia esula aka The Green Spurge''
| image = Euphorbia esula.jpeg
| image_width = 250px
| regnum = [[Plant]]ae
| divisio = [[Flowering plant|Magnoliophyta]]
| classis = [[Magnoliopsida]]
| ordo = [[Malpighiales]]
| familia = [[Euphorbiaceae]]
| genus = [[Euphorbia]]
| species = '''''E. esula'''''
| binomial = ''Euphorbia esula''
| binomial_authority = [[Carolus Linnaeus|L.]]
}}

'''''Euphorbia esula aka The Green Spurge''''' ('''Leafy Spurge''') is a species of [[Euphorbia|spurge]] native to central and southern [[Europe]] (north to [[England]], the [[Netherlands]], and [[Germany]]), and eastward through most of [[Asia]] north of the [[Himalaya]] to [[Korea]] and eastern [[Siberia]].<ref name=grin>Germplasm Resources Information Network: [http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?16366 ''Euphorbia esula'']</ref><ref name=flora>''Flora Europaea'': [http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Euphorbia+&SPECIES_XREF=esula&TAXON_NAME_XREF=&RANK= ''Euphorbia esula'']</ref><ref name=blamey>Blamey, M. & Grey-Wilson, C. (1989). ''Flora of Britain and Northern Europe''. ISBN 0-340-40170-2</ref>

[[Image:Euphorbia esula bluete.jpeg|thumb|left|Detail of flowers and immature seeds]]
It is a [[herbaceous]] [[perennial plant]] growing to 1-1.2 m tall, with several stems branched from the base. The stems are smooth, hairless or slightly hairy. The [[leaf|leaves]] are small, lanceolate, 4-8.5 cm long and up to 1 cm broad, with a slightly wavy margin. The [[flower]]s are small, produced in [[umbel]]s with a basal pair of bright yellow-green petal-like [[bract]]s. Clusters of the bracts appear in late spring, while the actual flowers do not develop until early summer. All parts of the plant contain a toxic white milky sap.<ref name=blamey/><ref name=rhs>Huxley, A, ed. (1992). ''New RHS Dictionary of Gardening''. ISBN 0-333-47494-5</ref>

It reproduces readily by [[seed]]s that have a high [[germination]] rate and may remain viable in the soil for at least seven years. The seed [[capsule]]s open explosively, dispersing seed up to 5 m from the parent plant, and may be carried further by water and wildlife. Leafy Spurge also spreads vegetatively from the [[root]] system, which is complex, reported to reach 8 m into the ground and 5 m across, and may have numerous buds.<ref name=nps/>

There are two [[subspecies]] and a [[Hybrid (biology)|hybrid]] subspecies:<ref name=grin/><ref name=blamey/>
*''Euphorbia esula'' subsp. ''esula''. Leaves broadest near apex; umbel bracts 5-15 mm. Throughout the range of the species.
*''Euphorbia esula'' subsp. ''tommasiniana'' (Bertol.) Kuzmanov (syn. ''E. waldsteinii'' (Sojak) A.R.Smith; ''E. virgata'' Waldst. & Kit.). Leaves broadest at the middle; umbel bracts 12-35 mm. Eastern Europe, western Asia.
*''Euphorbia esula'' nothosubsp. ''pseudovirgata'' (Schur) Govaerts. Hybrid between the above two subspecies.

==As an invasive plant==
Leafy Spurge was transported to the [[United States]] possibly as a seed impurity in the early 1800s. First recorded from [[Massachusetts]] in 1827, Leafy Spurge spread quickly and reached [[North Dakota]] within about 80 years. It now occurs across much of the northern U.S., with the most extensive infestations reported for [[Montana]], North Dakota, [[Nebraska]], [[South Dakota]], and [[Wyoming]]. It has been identified as a serious [[weed]] on a number of national parks and on reserves of [[The Nature Conservancy]] in eleven northern states. It is now classified as an [[invasive species]] by the [[United States Department of Agriculture]].<ref name=invasive>[http://www.invasivespecies.gov/profiles/leafspurg.shtml InvasiveSpecies.gov]</ref><ref name=nps>[http://www.nps.gov/plants/alien/fact/eues1.htm U.S. National Park Service description]</ref> It is also [[naturalisation (biology)|naturalised]] in [[Canada]] and parts of [[South America]].<ref name=grin/>

It displaces native vegetation in prairie habitats and fields through shading and by usurping available water and nutrients and through plant [[toxin]]s that prevent the growth of other plants underneath it. It is an aggressive invader and, once present, can completely overtake large areas of open land.<ref name=nps/>

Because of its persistent nature and ability to regenerate from small pieces of root, Leafy Spurge is extremely difficult to eradicate. [[Biological pest control|Biological control]] offers a highly promising management tactic for Leafy Spurge. [[Goat]]s, apparently able to graze on the plant without ill effect, have been used on [[rail trails]] in [[Idaho]] to clear leafy spurge from the [[trail]] [[Shoulder (road)|shoulders]].<ref>"War on Weeds," ''Rails to Trails Magazine,'' Spring 2004, p. 3</ref> The U.S. Department of Agriculture has shown success using six European insects that feed on Leafy Spurge. These include a stem and root-boring beetle (''[[Oberea erythrocephala]]''), four root-mining [[flea beetle]]s (''[[Aphthona]]'' spp.) and a [[shoot-tip gall midge]] (''[[Spurgia esulae]]''). Large scale field-rearing and release programs are carried out cooperatively by [[Federal government of the United States|federal]] and [[State governments of the United States|state officials]] in many northern states. The results are not as immediate as when herbicides are used but, if pesticide use is kept to a minimum, large numbers of these insects build up within a few years and have shown impressive results.<ref name=nps/>

Several systemic [[herbicide]]s have been found to be effective if applied in June, when the flowers and seeds are developing, or in early to mid-September, when the plants are moving nutrients downward into the roots. Preliminary research suggests that chemical treatment in the fall followed by a spring burn to reduce seed germination may be an effective strategy for reducing Leafy Spurge infestations. Multiple treatments are necessary every year for several years, making leafy spurge control an extremely expensive undertaking. If left uncontrolled for a single year, Leafy Spurge can reinfest rapidly. Prescribed burning, in conjunction with herbicides, may also be effective.<ref name=nps/>

==As a model weed==
Leafy spurge is being developed as a model to answer fundamental questions of weed biology. Over 55,000 [[ESTs]] have been sequenced from all plant tissues including tissues from plants that were cold-stressed, drought stressed, and plant being attacked by both flea beatles and gall midges. Analysis of the EST sequences indicated that 23,000 unique sequences representing more than 19,000 [[unigenes]] were obtained. These sequences are now available on [[Genbank]]. The unigenes have been used to develop cDNA [[microarrays]] that also include more than 4,000 additional cDNAs from [[cassava]] (another Euphorb related to leafy spurge). These microarrays are being used to identify physiological processes and signals that regulate bud dormancy (one of the main reasons leafy spurge is difficult to control), and invasiveness.

==References==
<references/>

{{Commons|Euphorbia esula}}

[[Category:Euphorbia]]
[[Category:Invasive plant species]]
[[Category:Flora of Europe]]
[[Category:Flora of Estonia]]
[[Category:Flora of the United Kingdom]]
[[Category:Flora of Michigan]]

[[de:Scharfe Wolfsmilch]]
[[fr:Euphorbe ésule]]
[[nl:Wolfsmelk]]
[[pl:Wilczomlecz lancetowaty]]
[[sq:Euphorbia esula]]
[[fi:Kenttätyräkki]]

Euphorbia esula - Revision history

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