Spring 2015. Lily of the valley, sometimes written lily-of-the-valley, scientific name Convallaria majalis is a sweetly scented, highly poisonous woodland flowering plant that is native throughout the cool temperate Northern Hemisphere in Asia, and Europe. It is possibly the only species in the genus Convallaria (or one of two or three, if C. keiskei and C. transcaucasica are recognised as separate species).