The taxonomic (i.e., "scientific") identity of the invasive leafy spurge found throughout the American West has recently undergone some reevaluation. This plant has typically been known as Euphorbia esula in the past, but in recent years a reassessment of the plant and its potential Old World sources has suggested esula was a misidentification. Most of the publications referenced on the YRLSP website were published before this reassessment gained currency. Today a more generally accepted identification is Euphorbia virgata.