dandelion clock

noun

noun

UK A single stem of a dandelion in its post-flowering state with the downy covering of its head intact.

Dandelion clocks! -- Pray what are they? ... by far the best clock is made by blowing the downy seed of the dandelion.1841 April 23, “Breakfast Table Science for Young People”, in Parley's Magazine, New York, page 112:

Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.