A batch of lemon balm-lemon verbena syrup reminds Jeanne of the multiple evolutionary origins of lemon flavor.
The citrus lemon itself is only one of many plant species that lends its namesake flavor or fragrance to our food and drinks. Lemon flavor primarily comes from a few terpenoid essential oils: citral (also called geranial, neral, or lemonal), linalool, limonene, geraniol, and citronellal. The production of one or more of these essential oils has independently evolved multiple times in species on widely separated branches of the plant phylogeny (see figure).