The dandelion, Taraxacum officinale, is a familiar perennial weed of lawns and meadows, its bright yellow composite flower opening with the sun and closing at evening, then ripening into the silvery seed-clock whose parachuted seeds scatter on the wind. Its English name comes from the French dent de lion, lion's tooth, for the jagged leaf. Two of childhood's small rituals belong to it: telling the time by the number of breaths needed to blow away the seeds, and making a wish as they fly. Every part of the plant is edible, and it has long been gathered as a salad green and a country wine.
Taxonomically the dandelion is a notorious puzzle: because most dandelions reproduce asexually through seed produced without fertilisation, a process called apomixis, populations split into hundreds of genetically fixed microspecies across Europe, so that specialists distinguish many hundreds of named Taraxacum microspecies where a gardener sees only one plant, one of the more extreme cases of taxonomic complexity in any common weed. Roasted and ground, the root has long served as a caffeine-free coffee substitute, dandelion coffee, a use that became especially widespread in wartime Europe when real coffee was scarce or rationed.