YOUNG CHILDREN have deciduous teeth. Our species gets one free replacement. Sharks and horses do better – their teeth continue to grow as they wear, at least for many years. All trees lose their leaves, but some do it continuously and replace continuously, and are known as ‘evergreens’. Even though they may never be really green, as with many eucalypts, they are never, if an ‘evergreen’, leafless. Deciduous trees shed their leaves in a month or so, after first withdrawing the nutrients in the reverse succession to the new leaves: chlorophylls, the green pigments out first, then the anthocyanins, the luminous yellow, orange and red ones last. These are the splendour of the Fall, as autumn is known in North America – a dramatically fitting name and a reminder of Puritanical origins. It is also etymologically proper.

The word ‘deciduous’ has Latin roots. ‘Cadere’ is ‘to fall’, and ‘decidere’ is ‘to fall down or off’. The Latin has given rise to several closely related words in English. All but one are specialised. ‘The Deciduata’, for example, are ‘all placental mammals that have a decidua’, a ‘decidua’ being ‘the lining membrane of the impregnated uterus in certain Mammalia’ [including our own species]; it forms the external envelope of the ovum, and is cast off at parturition'. ‘Deciduity’ is ‘a casting off’; some insects, female ants for example, have deciduous wings that fall off after copulation.