I really loved the In Bloom show at the Ashmolean :

"This major new exhibition takes visitors on a journey from Oxford to the farthest corners of the world and back, uncovering the global stories behind some of Britain’s most beloved blooms – from roses and tulips to camellias and peonies. Featuring over 100 artworks and objects, including drawings, paintings, rare prints, and ceramics, In Bloom explores our changing relationship with the natural world."

The Oxford Botanic Garden, which was established in 1621 and is the oldest in the U.K. still exists and is wonderful

45% of flowering plants are threatened with extinction

'Orchidelirium' was the Victorian craze for orchids

In the 19th century orchids symbolised wealth, romance and seduction

'Pteridomania' was the Victorian madness for ferns

The invention of the Wardian case facilitated long distance transport of live plants, such as ferns from New Zealand