Last Ice Age

The Last Ice Age functions in the book as a boundary in the classification of British plants, rather than as a setting for the walking narrative. The distinction matters because evidence of a plant’s ancient presence does not, in the account, by itself make that plant native.

Fossil evidence and native status

Fossils are cited as proof that rhododendrons grew in Britain before the Last Ice Age. The book contrasts that deep history with the rule it describes for native status: plants qualify if they flourished after the ice had receded. The period therefore marks a threshold in the account’s distinction between having once grown in Britain and belonging to its post-glacial native flora.

A boundary with conservation consequences

That distinction shapes the discussion of rhododendrons introduced back into Britain in the mid-eighteenth century. Although the plants had prehistoric roots in the country, their later return did not place them within the account’s definition of native plants. The National Trust’s decision to remove them from a Welsh valley followed this contested classification; the resulting clearances left damaged-looking hillsides, while surviving stumps regenerated and native growth remained scant. The episode shows how a historical boundary can inform present-day conservation decisions, without settling whether either side of the resulting ecological conflict is better off.

Role in the narrative

The Last Ice Age appears briefly, as a point of comparison that complicates a simple opposition between ancient presence and introduced invasion. It gives the narrator’s description of the rhododendrons a longer timescale, while keeping attention on the visible aftermath of human decisions in the landscape.