Reference

Bruno A. Mies, Maria Soledad Jimenez, Domingo Morales (1996): Ecophysiology and distribution of the endemic leafless spurge Euphorbia aphylla and the introduced E. tirucalli (Euphorbiaceae, Euphorbia sect. Tirucalli) in the Canary Islands – Österreichische Botanische Zeitschrift = Plant Systematics and Evolution – 202: 27 - 36.