See under prickly poppy.
Origin of Mexican poppy
An Americanism dating back to 1840–50
any tropical American poppy of the genus Argemone, especially A. mexicana (Mexican poppy), having prickly pods and leaves and yellow or white, poppylike flowers.
Origin of prickly poppy
First recorded in 1715–25
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
an annual papaveraceous plant, Argemone mexicana, of tropical America, having prickly stems and leaves and large yellow or white flowers
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012