Leafy spurge infestation in Montana.
Photo © Norman E. Rees, USDA Agricultural Research Service.
AUTHORSHIP AND CITATION:
Gucker, Corey L. 2010. Euphorbia esula. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [ ].
NRCS PLANT CODE :
The scientific name of leafy spurge is Euphorbia esula subg. Esula L. (Euphorbiaceae) [42,58,89,155].
Kartesz  recognizes 3 leafy spurge varieties: leafy spurge (Euphorbia esula var. esula), Oriental leafy spurge (E. esula var. orientalis), and Russian leafy spurge (E. esula var. uralensis). Plants Database  recognizes only 2 varieties: leafy spurge and Russian leafy spurge. However, after analyzing 26 morphological characters for 600 Euphorbia species within the Esula subgenus, Crompton and others  concluded that in North America, leafy spurge is a single, variable species and has hybridized only with cypress spurge (E. cyparissias). Considerable taxonomic confusion surrounds leafy spurge varieties, subspecies, and hybrids (see the Synonyms section below). Likely multiple introductions of leafy spurge into North America resulted in a complex of variable genotypes .
Hybrids: Only the tetraploid cypress spurge type is known to hybridize with leafy spurge [147,167], resulting in the hybrid, Euphorbia × pseudoesula Schur. [42,146,147,174]. In Canada, Euphorbia × pseudoesula has been collected from British Columbia, Saskatchewan, and Ontario , but hybrids are possible anywhere leafy spurge and the tetraploid cypress spurge type occur together.
for Euphorbia esula var. esula:
Euphorbia intercedens Podp. [41,89,221]
Euphorbia podperae Croizat 
Euphorbia × pseudovirgata (Schur) Soó [51,60]
Galarhoeus esula (L.) Rydb. [89,221]
Tithymalus esula (L.) Hill or Scopoli [89,221,232,233]
for Euphorbia esula var. uralensis:
Euphorbia esula var. orientalis Boiss. 
Euphorbia esula ssp. tommasiniana (Bertol.) Kuzmanov [41,174]
Euphorbia uralensis Fisch. ex Link [41,174]
Euphorbia virgata Waldst. & Kit., non Desf. [41,51,60,89,221]
Tithymalus uralensis (Fisch. ex Link) Prokhanov [89,221,232,233]
Complete FEIS review for Euphorbia esula
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