Botanical drawings are at risk of leaving the UK unless a buyer can be found to pay £2.5 million.
An export bar has been placed on the 18th-century, hand-painted early depictions of plant specimens, which were drawn as they were being introduced to the UK.
The works, The Natural History Of Carolina, Florida And The Bahama Islands, and A Commonplace Book, were completed in the mid-1700s.
Arts minister Helen Whately said: “The intricate drawings in this collection offer us a special insight into how new discoveries and images of plants and animals in far-off lands were shared before the advent of modern technology.
“This collection is a hugely important resource for future generations and I hope that a buyer can be found so these works can be saved for the nation.”
Naturalist Mark Catesby’s The Natural History Of Carolina, Florida And The Bahama Islands contains printed text and hand-coloured etched plates, depicting plants, birds and animals.
Gardener and plant collector Peter Collinson’s work, A Commonplace Book, includes “exceptional” early depictions of botanical and zoological subjects from across the globe.
The decision on the export licence application for the albums will be deferred until April 16. This can be extended if a serious intention to raise funds to purchase it is made at the recommended price.