[Wikipedia] Southern Europe, northwest Africa, and eastward through southwes: Euphorbia lathyris, the caper spurge or paper spurge, is a species of spurge native to southern Europe (Italy, Greece, Spain, Portugal), northwest Africa, and eastward through southwest Asia to western China. (link added by Mary Ann Machi)

[pfaf.org] Toxicity: The sap contains a latex which is toxic on ingestion and highly irritant externally, causing photosensitive skin reactions and severe inflammation, especially on contact with eyes or open cuts. The toxicity can remain high even in dried plant material[200]. Prolonged and regular contact with the sap is inadvisable because of its carcinogenic nature[214]. The seed is also poisonous[76]. (link added by Mary Ann Machi)

[plants.ces.ncsu.edu] Invasiveness rank: Diseases, Insects, and Other Plant Problems: No known diseases or insect problems. In western and northern states of the US, Leafy spurge is considered an invasive, noxious weed. The World Conservation Union (IUCN) has placed this species on its list of 100 of the world's worst invasive species. (link added by Mary Ann Machi)